Johnson, Evinrude, OMC, outboard motor, outboard motor repair, outboard troubleshooting, 9.9, 15 hp, year of manufacture, water pump, carburetor, long shaft, 15 hp conversion, sailmaster


Overview of Repairing / Storing Outboard Motors


Is it Worth Fixing, By the Way How Old is it ?   OK, you will probably not be looking at these articles unless you have a motor that needs some sort of repairs. 

First off, outboard motors normally do not wear out or die by themselves, THEIR OWNERS KILL THEM.  This is usually because of lack of understanding where they CAN NOT just be laid in the corner for years with no preliminary maintenance.  They are not like a garden hoe or shovel that can survive time with nothing being done to them.  I will cover this proper storage preparation at the very end of this article.

In this article I will not deal with any specific make of manufacture or model, but just what to look for and in close proximity of and what order to look at.  Many times you enter into a situation where someone is posting information on a on-line message board, there seems to be a lot taken for granted as to "Existing General Knowledge" as related to outboard engine repair.   In this article I will try to explain as much as possible in very simple language, however this is not possible without using the proper terminology.  We will be dealing primarily with small 2 cycle motors up to about 10hp here, but the principal is the same for all sizes.

First off let us assume that you have at least a small amount of mechanical knowledge.    If you do not know the difference of a #2 Phillips screwdriver from a 8" adjustable spanner (Crescent) wrench, and you do not have the ability to read and at least comprehend even the least bit if information, then you probably had better take your problem to a professional then make a deposit into his bank account for his experience.  You can invest in outboard repair manuals and books, spend some time digesting what they are saying as to what they really mean by looking at your motor, do your own wrenching trial and error repairs.   I will however 98% guarantee that you will not have instant gratification the first time around because of your inability to understand how the motor was made and how they function.

These outboards, like any that get used and or abused may need to be torn apart and repaired over time.  Parts wear out or need adjustment.  As they get older, the depreciated value of a somewhat neglected/abused motor is such that with a motor in the 25 to 35 year old range, it could be questionable as to whether taking it to a outboard mechanic is worthwhile for other than electrical trouble shooting type of repairs.  Most shops now charge from $85 to $90 per hour.  Some shops even refuse to work on anything over 20 years old.  I have seem some newer abused motors where I would not pay $50 for, and then again a older one that has been used but maintained, may be worth from $500 to $1000, depending on the year, compression, whether it is electric start, a longshaft or not. 


It is my observation that most outboard motor problems are not that the motor is worn out, but it is the NEGLECT / ABUSE  and lack of care it received over it's lifetime.   An older well cared for motor, is worth way more than a newer neglected / damaged motor.   Many of the OMC motors from the late 1950s up to mid 1970s use magneto ignition and are reliable, and then in the era of 1980 to 1992 where they are into the electronic ignition era and almost bulletproof if at least some resemblance of care is performed on them.  The Chrysler brand can also be decent workhorse motors, however replacement parts can be expensive.  Generally older Mercury motors are not looked on as easy or inexpensive to repair.

This article is not meant to take the place of a service manual.  It however has some tips from my personal experiences along with other information that has been gleaned from many sources over the years that may make owning and /or repairing your motor a little easier to understand.  It started out as a documentary as to what I had learned on my own motors to myself, as I seemingly have become more forgetful as I pass 75 years of age. 


Most commercial outboard mechanics have to work on many different makes and sizes of motors in order to make a living, therefore it is unreasonable to expect them to remember the whole history along with the little extra things to look for when repairing one particular make and model.   Hopefully this article will help those mechanics or those of you tinkerers who do decide to "DO IT YOURSELF".


Worn Out ?  Here is a question that was posed to me.  Over the years I have heard people, even mechanics say, that when a 2 cycle engine is worn out, you might as well just toss it because they aren't worth rebuilding.  But, as a longtime maintenance mechanic, I can't imagine that they can't be rebuilt, and throwing out, say a 120hp four or six cylinder 2 stroke engine that may have originally cost over $5000 seems a bit extreme.  I mean, even a worn-out motor would still have a salable parts value (and sometimes even more than if it was running).  Why would someone say that?   Is it that they are too expensive to rebuild?  Or do they just do not understand repair procedures?  Or being a salesman they want to sell a newer motor?

My response.  "First off you need to define "Worn Out".  Worn out and throw away is just an excuse for their inability to be a good mechanic.  However sometimes just the cost of  diagnosis can be more than the current value of the motor.

Most outboard motors, do not die, their owners kill them.  Most owners have no real concept of any maintenance.  As long as there is gas in the tank, the battery is charged and the boat's drain plug is in, they jump in and GO.

Inactivity of any motor that has not been properly stored is not good.  A motor that is ran at least once a month is way better than a few week-ends a year.

Then most people, even some mechanics do not truly understand 2 cycle operations.  Troubleshooting is usually learned by being exposed to them for considerable time and being able to diagnose what is/is not happening.   Once you acquire the basics all else seems to fall in place.  Not all mechanics have this ability.  Then some brands of motors are not that easy to work on either. 

On the other hand, when I ran my business (Gunsmithing), if I intended to stay in business, I did not feel that I should charge the customer for my learning experiences.  This can not happen in modern day marine mechanics where the business owner is not the actual mechanic and has to charge for actual time involved.

Also on many of the older motors (which are actually easier to work on because of less or simple minimal electronics) modern mechanics that can not diagnose problems without swapping parts (which they then can not later ethically resell) hesitate to even get involved because of the potential cost (usually over $85 an hour labor) plus parts AND if the problem still is not rectified completely, they do not really want to touch the motor because they need to make money and to have happy returning customers.  Happy customers need to get good service at a decent price.

Now most mechanics that do this for a living can not be conversant with every make/model even if they specialize in only one brand.  So they have to go to service manuals.  These manuals MANY times are not that complete and usually only cover repairs for NEW motors, not old worn ones that may have multiple issues where diagnosis issues are not really covered.   Then they have no way of knowing what "repairs" any previous owners or mechanics may have attempted.

You would be surprised at just how many marine mechanics do not even look at the internet for information.  Their excuse is either "I don't have the time" or "we have the manuals here", or "after working all day on them, I do not want to do it at night".

Some older motors are very well made and stand up quite well if taken care of (some even if abused).  They can even be rebuilt back to factory new, reasonably, (except Mercury) if you do it yourself.

Older Junker motors are valuable now for spare parts, where many are stripped down and sold on eBay.  Smaller motors, (under 20hp) seem to be more in demand than larger ones."

Do it Yourself ;  If there is any chance that you do decide to work on it yourself, it is highly recommended that you purchase one of the excellent illustrated service manuals (preferably the factory ones for your specific motor) that covers your motor before you venture too far into trying to repair something you may not be that familiar with.  It is also highly recommended that you get a factory parts catalog for the year of motor in question.  However many of these shop manuals are written for skilled/trained techs who already know most of the workings of these motors so will leave the novice scratching their heads at times.  But with these manuals you can see the exploded view of the parts and can order by part number. The part numbers may have been superseded, but the shop you go to when ordering parts, can cross-reference to the new number.  This parts manual also helps you positively identify the part you need, as compared to ordering something by the wrong name and getting the wrong part.   Remember, most of mechanics/counterpersons flunked mind-reading school.  These parts manuals will also provide a picture placement of the related parts.

One source of original or reproduction manuals would be to go to and then type in outboard motor or to narrow the search, the brand and model, even the year may help.  Used original parts manuals for many of these motors usually go for from between $5 to $20 and are more in demand than the service manuals.    Original, or copies of the manufacturers Service Manuals for the year motor you are working on would be best.  Undoubtedly the parts manuals are very important to the home mechanic.  Aftermarket repair manuals are generally a waste of money in my book.  They cover so many models that it seems what you are specifically looking for will never be there.  But buy both, which may help you read between the lines.

The service manuals are very helpful and do (or should) explain in detail just how to repair the motor.  You really need both the service manual and the parts manual. 

Owners manuals do not really help you when doing repairs, they just give you pointers on how to adjust carburetor, the trim and how to jeep it clean. 

Also be aware that when you go to the dealer to order parts, that many times some of the larger dealers would rather you brought your motor in to them to work on.  Remember that they need to keep their employees on the payroll.  Therefore they possibly may resist ordering parts for you by saying that they are hard to find.  Or if they do accept your order, they may not place your parts order at the top of the "To Order" priority list, since you are planning on doing the repairs yourself.   However if you go to them with part numbers, they may be more obliging to place an order, since the monkey is on your back for providing the right or wrong part numbers, and you are then obliged to pay for them even if some wrong parts show up.  However, if you do come up with your own numbers, also supply the description, so they have some idea of what it is if they need to do a cross-reference of superseded parts.  It would also be best to indicate which year of parts list you used, as many of these older parts numbers have been superseded by newer numbers.  

Another thing to consider is that most times the manufacturer or distributor like to have an order from the dealer in minimum quantity or dollar value to cut down on excess shipping.  There is the possibility that the dealer may have just placed an order and will not place another until they get enough accumulated to qualify for another order.  They will undoubtedly want you to prepay for the order.  Also when the order comes in, even though you requested them to call you, with possibly more than one person in the shop, that information may have gotten misplaced.  They should however, be able to give you an estimated delivery time.  But don't call them and inquire for at least for a couple of weeks.

You can look up needed replacement parts and order online thru this LINK.

I am not an outboard mechanic, but a retired machinist who has been working on these older motors for over 40 years.   If you are like me, and do not have anywhere near a photographic memory, by the time you tear it apart, get the parts ordered, then try to reassemble it weeks later, you can not really remember the exact sequence or placement of some critical parts.   Also someone else could have worked on it in the past and the part may not be where it actually belongs.   Most times you can figure it out by trial and error, but proper placement of others that may be somewhat internal, where if you guess wrong, may require the whole engine or lower unit to be disassembled again just to reposition or add one forgotten part, (been there-done that) which can be frustrating.  This miss-placement of a part will usually come to you some time later, and usually in the middle of the night. 

With the digital cameras commonly in use now, this may be a good way to record what things should look like before or while you take it apart.   If you tear it apart more than just to replace some small item, take a few digital pictures of the motor with the cowlings off.  

This is Not Really a Trouble-Shooting Article :  You will find my troubleshooting article by itself.  In the following information provided in this article, it is ASSUMED that the motor is in a good enough condition TO run.  If you have bad spark plugs, rings, carburetor being fouled, or anything that may contribute to the engine not running then you will need to address that situation, especially as a pre-requisite to doing anything else.  Any work needed should also be done in addition to what  is covered here.  AND, we are assuming that you have the motor mounted on the boat transom properly with the cavitation plate even with the hull's bottom and the motor tilted at an angle that lets the cavitation plate be straight with the bottom.


All the above said, if you happen to be one of those persons who should not be left alone with a pencil sharpener or even dull knife and do not have the ability to read and at least comprehend even the least bit if information, it may behoove you to not try to work on your own boat, motor or trailer.

Free Advice :  You may find persons who offer free advice on about any subject, outboard motors "experts" are no different, but I have found that MOST of these Good Samaritans may not be as good as they think they are.  I sometimes even find out things that may have been obvious, or I had not even considered before.  Some like to talk just to try to impress people, (I call this BULL SHIT) but for those that are knowledgeable on that subject, it does not take long to distinguish their status.  

If you happen to frequent some of the boat or motor message boards, you will soon see a response to the question of a motor not running exactly right.  The most common response is to rebuild the carburetor.  OK, this may be part of the problem, but it is not the cure-all, as your problem could also be ignition or compression related.   Another response often seen is that you should replace the water pump impeller every 2 to 3 years, just a a precautionary measure.  This might be so, IF you are operating in VERY MUDDY, SANDY or debris infected water, OR are using it as in a main motor that is used MANY miles offshore and you have no backup.  The current new impellers should last for MANY years if the motor is treated right.   I replaced one of mine after 20 years, it was still intact and functioning, but to what degree of originality I could not tell, (memory problem for a 74 year old geezer).   It however was not as pliable as the newer one I replaced it with.  The reason I replaced it is that I was adding a long shaft unit and decided while I had the lower unit off, that I has just as well replace the water pump impeller at that time also.  However any impeller could be ruined after only a few seconds of running without water (also been there-done that, in one of those brain fart instances).


A few years ago, I purchased a 70 hp Johnson from a private individual, when I was looking at it prior to the purchase, I asked if it ran, he immediately reached over, twisted the ignition key and started it, (it was still on his boat & trailer sitting in his driveway).  THE MOTOR WAS NOT HOOKED UP TO WATER MUFFS.  I quickly told him to shut it off, his reply was, that's OK, I ran it like this yesterday.  I immediately looked under the hood for evidence of overheating (which there was none) but deducted $100 off my offer.  And YES the impeller was totally demolished, having the tips of the vanes worn off enough so that it would have pumped very little water while plugging the water tube with ground up rubber if it did. 

Proper Repairs ?? :   There are many ways to repair anything, with outboard motors not excluded.  You can skimp by and just repair or replace what is needed to keep it running so there may be a place for this type of repair.  Or you can go one step farther, clean up plugged water passages, or replace any other parts you find that are not really up to par.  This extra could be a frayed starter rope, a hardened fuel line primer pump, twist grip throttle gears that jump out of mesh, or a leaking gearcase drain plug seal.   I for one do not like the idea of fighting my motors just to get me to, or more importantly, getting me back from the fishing area.  This can also cut deeply into your limited fishing time.  It is a lonely feeling to be dead in the water, and paddling against the tide or wind, is not a very rewarding situation, it may however become exciting.

Most parts for these motors are still available from different sources, either new or used, however price may be prohibitive on some cases.  With this in mind you may consider making or repairing your own, or purchasing replacement bolts from the hardware store.   Now I am not saying to tie the broken twist grip handle on with bailing twine, but I am sure human ingenuity can prevail if the need arises.

The mechanical repairs are a usually no brainer, but electrical problems can well be aggravating until you get them figured out.  And since you and I do not normally have lots of new or even used parts that are known to be good, it is hard for us to simply swap out parts until we find what is wrong.  One internet parts supplier includes a sheet listed below with their shipped parts.

"---WARNING --- The outboard marine ignition system is one of the more comprehensive electrical designs in the market today.  The most common error made by the mechanic or the owner is to simply replace a defective component within the system without determining what exactly caused it to fail.  "Did a shorted rectifier cause this problem?" or "Did the owner charge his battery improperly?" ; are just a few questions that reflect a couple of the many possibilities for failure.

  Make sure your part is defective for the right reasons.  Always consult your maintenance manual to see that the part you are replacing is the problem and not the result of the problem.  If this is not done, failure will only happen over and over again."

Spare Parts Availability :  Most marine repair shops even though they may not be a OMC/BRP, Mercury or dealer, can get parts if they want to.   However a big Honda or Yamaha dealer may not be interested in helping you in the least, where a smaller independent mechanic may.   The one online marine dealer that seems to have factory parts for most models is .  Their website has a online illustrated parts listing.  Their parts are discounted off retail prices.  They even have a parts technician that you can call to verify if you encounter any questions.   I am not sure how old of models that they carry parts for, but I had no problem getting water pump parts for a 1977 Mercury 4.5 hp.  They then ship FedEx.

Here is another source where you can look up needed replacement parts and order online .


Also, you can go to any Car Quest automotive store and request a "Sierra" marine parts catalog.   NAPA  also has a "Marine Catalog", which by the way, uses the same parts numbers as the Sierra catalog.  These catalogs will not have all the specialized individual parts like motor mounts or decals, but they do list most pistons, rings, bearings, gaskets, seals, water pumps, fuel pumps, impellers, along with many ignition parts.  They also will not have current production parts within the last 5-10 years, forcing you go to the marine dealer for them. 


The one thing about the above catalogs however, you may need the manufacturer's parts manual to give you some of the original part numbers, to properly identify the needed part.   But also bear in mind that even OMC changes / updates part numbers.  This means that the number you get out of a 1983 OMC parts book, if the part is still available, may be changed to a totally different part number.  So to help the dealer, you also need to identify the motor and year of the motor in addition to your part numbers so if you got the number wrong or the part may be obsolete, the dealer can look it up in the current parts/price update list to get current part numbers if applicable.

Some Shops Refuse to Work on Older Motors :  There may come the time when you do need to take it to a marine mechanic, because you simply do not have enough spare parts to exchange in testing, or the needed electronic test equipment to diagnose a ignition/electrical failure.  A few years ago I ran into a independent marine dealer who informed me that they will not work on any motor over 20 years old, this 9.9 OMC included.  Their explanation was that parts for many of these older motors are not obtainable.  I had what I thought was an electronic problem and in that year (2002), I took my motor in and presented this dealer a complete list that contained the motor year, model, serial number along with all the previous repairs and the things that I had done to the motor, like compression test, spark jump test, how it was acting etc. 


Now, their refusal may be understandable in one sense, but for this particular series motor that had not really changed that much during a time span of 18 years, with the last of this series being made in 1992 (only 10 years before), and with parts still available from Bombardier, it seems like they are not really interested in giving service.   And I for one, will seriously consider whether I need to patronize them again, unless it is an emergency on my part.   Recently I have heard of another shop doing the same.  My suspicion is these shops are not run by the owners, that their mechanics are of the younger generation and have not been trained on these older motors.   Whereby they consider these older motors only good for anchors.


I recently talked to an independent small engine mechanic, but this time a late 9.9hp Mariner 4 stroke that was equipped with a Yamaha powerhead that he was working on for a customer.  This would have been common in that Mercury used the Yamaha powerhead on their 9.9s at that time.  This same above mentioned dealer refused to even offer any advise as to a choke solenoid problem and even told this mechanic to never bring it in or even bother him with this JAP import again.   Now what makes this is odd, is that this dealer is still a Mercury sales and repair dealer, and even has many certification plaques on his wall.  OH well, he must have enough business that he doesn't need more, AND/OR he really doesn't know how to work on these motors to start with and is smart enough to not want to show his ignorance on this subject.   Or he has a dislike for that independent mechanic who he may see as undermining his business.

It seems that we here in the US are spoiled by being able to at least find a marine repair shop within a reasonable driving distance.   In other parts of the world, they are non-existent and if you do find one, the word is that service is lacking possibly because of lack of parts availability, or that they do not see as many of these US motors whereby that knowledge may also be lacking.   In my previous service repair type business I made it a point to not charge my customers for my learning experiences.   I just heard from a friend in Germany where outboard mechanic labor equates to $125 per 15 minutes work.

Since I have had these articles posted on the internet, you would be amazed at the pleas for help that I get from all over the world.  Most of these requests from stateside for information are covered in my articles, just written a little different format than the question.   Or they did not read the whole article or related ones.  There is a lot covered here, and needless to say may need to be re-read numerous times to digest something that the average person may not be familiar with to start with.

Story #1 --   I had acquired a used 1974 "rebuilt" powerhead off eBay that was supposed to have run hot after a recent rebuild.  The owner got exasperated, stripped the motor down and sold the individual parts.

When I got it, and since it was just a powerhead and readily accessible, I wanted to find out any potential problems before I put it on an ailing motor that I had acquired earlier.  Upon disassembly, I discovered that YES,
it had seen a wrench before.  Namely a different (red) gasket sealer material under the head gasket, powerhead to upper housing unit and also under the water jacket, indicating that someone had at least had it somewhat apart and looked at it in the not to distant past.  I did also find evidence of the same gasket sealer in between the front and rear sections of the block, so at least the block had been apart and possibly there were new rings put in.  OH yes, and it had a recent gray paint job.

The head and head gasket came off the block OK, but the head gasket was still stuck to the head.  The previous mechanic had not removed the gasket off the head in an apparent attempt to do a cheap overhaul by using the old gaskets.  The suspicion on my part was that this was probably because they were afraid if they tried to take this gasket off the head, that they would ruin the gasket and could not use it over again.  There was however new sealer material between the gasket and the block.

What I did find, was that the motor apparently had been in salt water numerous times, had not been flushed well, if at all.  When I took the gasket off the head, there were salt crystals/aluminum corrosion pretty well blocking the lower cylinder's water jacket passage in the head.  This model has the thermostat at this lower location.  The water passages in the head were blocked solidly enough that I doubt that very little water could have even passed on into the completely plugged thermostat, much less on thru the rest of the engine and on out.  Pictures are shown in The Water Circulation Problems section in it's own article.

After I got the powerhead placed on my other 1974 motor that had a rusted crankshaft, I had problems keeping the motor running right.  Compression was 102 and 105.  I had put new aftermarket points and condensers in it among other things, but had problems that I eventually tracked down to mismatched flywheel and crankshaft tapers which kept shearing flywheel keys.  This motor would run OK on 2 cylinders, then down to one, then hard to start, and I was chasing my tail.  I finally took the timing plate and main ignition coil to a marine mechanic when I was in his locality to have the coil checked.  In order to check it he had to remove the screw holding the condenser to the points.  The ignition coil checked out OK, but he recommended that I purchase new points and condensers.    He said the points looked pretty bad.   BULL $HIT.   Well, I understand a shop wanting to replace anything that may have been a potential problem when they do a repair so that the job will not come back for a free repair later.  However I was doing the repairs and on these points, he could not see inside of the contacts without totally removing them from the timing plate and then taking them apart so he could really inspect them.   And being new, they probably only had an hours run time on them.   He must have better than my 20-15 vision.  I did buy the condensers from him, checked the grounds, repaired the flywheel taper, replaced the key and got it running.

Story #2 --  Another situation presented itself that bothers me, relates to dealer ethics.   I again purchased off eBay a 1987 15hp Johnson motor for $76 that was sold as "needing repair/for parts".  It was close enough to me (150 miles) so I took the wife for a drive and personally picked it up from the young man.  He advertised it as needing rings and that he had the marine shop's estimates.  He is a young Coast Guardsman who had gotten the motor from his father 2 years before but had never ran it.  On his first attempt ever to start it in the spring of 2005, it would not start, so he took it to a marine repair shop in a decent sized town located on salt water with lots of boat traffic, which should have had enough exposure to be pretty well acquainted with outboard motor problems, plus they did all the Coast Guard's repair work (why he took it there).  He had also broken the starter rope in his efforts, since he apparently was not aware that the motor needed to be in neutral when trying to start it.  The work order he gave me from the dealer says "low compression - pull head & diagnose, & call with estimate.  recoil repair".

The diagnosis reads
"Bad Rings - new power head, not cost effective to repair unit"They had taken the head off, inspected the piston,  re-bolted the head back on lightly and without the gasket (apparently to prove they had it apart).   The headgasket, broken recoil starter rope and handle were stuffed under the motor's cowling.  The estimate of needed parts included carburetor kit, fuel kit, water pump kit, rings, rod bearings, wrist pin and bearings, main bearings and seals, oversize pistons plus a rebore to match pistons and a thermostat for a total parts estimate of $294.  This mind you did not include over $400 for the labor.

OK, on the surface this looks like it could be appropriate.  But after I got it home, I noticed on the top of the flywheel was written in felt pen, "Comp 1 -  100#,  2 - 105#,  spark OK".  I took the head back off and the pistons were clean, with no carbon, however there was wear of about .010 of apparent piston wear.  Yes, it was
WORN a lot as the pistons could be wobbled somewhatBut my thoughts were if compression was at the 100#,  why did they even take the head off?   I just reassembled it using the original head gasket with some gasket sealant.  I had a used starter rope that I installedBUT -- the one thing I did install that was missing, was the "C" shaped horseshoe clip in the kill button on the end of the twist grip.

I had the motor running within 3 min.  My question is, how did they check the spark without using their own clip on the kill button.  And with the broken starter rope, they would have to have used a emergency starter rope to get the compression, which would not have been an impossible thing.  However it would appear that they never told the young man about the "kill override switch, otherwise known as man overboard switch" was
missing.  OK, maybe this now running motor is not 100% factory new, but it ran for 2 fishing seasons for me as a normal fishing motor before it finally fouled the plugs so bad that it needed new pistons and rings. 

My guess is that this young man did not know anything about the "Man Overboard Kill Switch Lanyard" that was missing.  With this gone, it was essentially like turning off the key.  They could have replaced the starter rope, changed plugs, adjusted the carburetor idle and charged him $100 to $150, he would have been happy and they could have made a enough to cover the diagnosis and the actual repair to have also made a profit.   I will bet they even tried to sell him a newer motor and/or offered him a minimal trade in.

Story #3 -- I happened to be talking to my neighbor and school mate when I spied an older 1960 10hp QD Johnson, I asked how it was running.  His response was, well it had belonged to his Dad many years before and had been setting for some time,  when his sons decided to use it, sad to say the water pump did not function.  They took it to an independent marine mechanic (well known to the locals as being a scalper), who replaced the water pump impeller for a mere $200.  They thought they got a good deal, as he told them that a new motor of that size would have cost them over $2000. 


This may not have been a proper comparison as he was referring to a new motor, but in any event the repair was still about 1/2 of the price of a current used motor of the same year.  This mechanic should have had less than an hour labor and possibly $20 worth of parts in this repair.  I have since had a chance to inspect his repair on this motor and it appears that he just installed a new impeller that is a simple repair, that I have done on this series motor in less than 1/2 an hour.  From the experiences I have had with this mechanic, he is one of those smart A$$es, looks at how you dress, the vehicle you drive, plays a sucker game and adjusts the price accordingly.   His cash register is his wallet and of course no receipt. 

Just one more of the reasons why I am writing this article.


1967 Johnson 3hp folding motor

Here it is ; 
Let us assume that have acquired a used new to you motor (or your neighbor brought it to you to get it running) and you know nothing at all about the motor staring at you.  First thing I would do is to pull the starter rope to see if the motor is not seized or frozen up in some manner.   If so, it could be a rusted, blown or seized piston, or even a frozen gearbox.  Any of the above, would indicate that way more diagnostic and repair work would be required than a simple (or not so simple) just putting new gas in and getting it started situation.  This would be the first of a check-off list as to this motor possibly being a candidate for the used parts / junk pile.

Try to find out some sort of history about it if at all possible.  Now also take into consideration the source of your information.  If the person just happens to be selling it, many times, they stretch the truth more than as little (remember they could also be fishermen).  If you can come up with any information at all, this may help you instead of doing all your own detective work.  When I say detective work, it is just that, you need to know what requirements are to make the engine run and be able to go thru a check-list.   One small overlooked item may be the key to getting your motor to function.   And remember just because you found pieces or parts installed in a certain way does not mean that this is the proper installation if someone has had a wrench on it before.

Inspect the motor, the general overall condition can give you some indication as what to expect.  Has it been USED or has it been ABUSED?  There is a distinct difference here.   Are any parts missing?  Can you see any new gasket sealer at some parts joints of the block or under the head?   Has it been recently repainted?  The above two are indicative that someone has been working on it, WHY is the question you need to ask now that you have been delegated to get it running since apparently they could not?   Here we are making an assumption that the motor is not seized up in any manner, be it pistons or gearcase.   And all that is needed is much Tender Loving Care to get it purring again.

How Old is It ? ;   In most cases the person trying to sell a motor does not really know the year of production.  They are not really into outboard motors, are selling for a friend or relative and only pass on what they were told.  If there is a chance to gain a few dollars because of a misstated year (saying it is newer than it actually is) is VERY COMMON.  Some motors have a date code, while others go by serial numbers, but in either instance, you have to have the reference in your pocket when you go to look at a prospective motor to purchase, or be very cognizant with those series of motors.

If the above motor happens to be a pre-WWII motor, or even a few years later, like up to mid 1960s, replacement parts may not be easy to find.  You will most likely need electronics, like coils, possible points,  or condensers.  However most points can be cleaned up, and condensers rarely fail.

Trying to identify an old motor can be a challenge, here is a website that may help .  But if you need help even for some parts, also try these websites.

I will not repeat myself here, so for a more detailed listing of troubleshooting  CLICK HERE.

Lower Unit or Gearbox ;  All motors will have a lower unit or gearbox that transmits vertical power from the motor to horizontal power to the propeller.  These lower units houses the gearbox so it can be separated from the mid-section or "leg", by a few bolts.  Finding a replacement water pump impeller may be a problem on some of the older motors that were sold by mail order stores.

In the photo below, this gearbox off a 18hp 1959 Johnson, did not have any nylon washers under the drain or fill plugs, no spaghetti seal at the juncture of the top and bottom halves of the gearbox (just Permatex and not much of that) and had probably not seen oil for a good number of years, water yes, but no oil by then.   Surprisingly, the motor ran, but did not have a lot of power to overcome the restrictions inside the gearbox.

About all it is good for now is photography purposes.

Here is what a boater does not really want to see

Decarb ;  Chances are good if the motor has set for any length of time and you may not know anything about it, that the rings may have become stuck in the piston.  This can hamper the running of the motor because of lower compression The easiest way to help here would be to purchase a commercial de-carbonizing liquid that is ran thru the gas and / or squirted into the pistons, let set, then run it.  One that is usually available at automotive parts stores is SeaFoam.  This stuff softens the carbon buildup and when the motor is then ran it blows this now softened carbon out the exhaust and many times gives the motor a new lease on life.  

One method of decarbing used by many is to mix a strong mixture of SeaFoam into a 1/2 gallon of mixed fuel, make up a small fuel tank with fitting to the motor if applicable and run the motor at a medium speed  let most of the fuel be consumed and shut the motor off.  Pull the spark plugs, squirt more SeaFoam directly into the spark plug holes.  Let the motor set for 20 minutes, then start it up.  If you have carbon internally the motor will burn this loosened carbon which will SMOKE considerably.

Check List For Storing Your Outboard Motor ;  This is many times listed also as "Winterizing".  The sequences could be different, but the ultimate goal is to drain the fuel out of the carburetor, check the lower unit gear oil for water intrusion, then clean and grease any metal that has a potential to rust.  If it is going to be stored in an area where the weather could be conducive to the internal parts of the motor "sweating" then some sort of oil needs to be protecting the internal parts (fogging).

Here we will be generic, and leaning toward 2 cycle carbureted motors under 40hp, many of which will be removed from the boat for extended periods of time, for from just over a winter or for an unknown extended time period.  Here, you have a choice, fog the engine or run it dry of fuel.  Each has it's benefits, however fogging is preferred for long term storage.

(1) Run the motor either in a barrel or using muffs.  Some of the newer motors come equipped with a “flushing plug” which can be attached to a hose for flushing the engine with fresh water.  Let it run long enough to warm it up and verify that it is indeed running right.

(2) For fogging, remove the carburetor breather, with the motor running at a mid level speed, spray a winterizing/fogging oil into the mouth of the carburetor/s.  Spray it in enough so that the motor starts to bog down and dies.  This oil has the capability of being somewhat sticky and when sucked into the crankcase of a 2 cycle, protects the crankshaft, bearings and cylinder walls.  When it is started later on down the road, it will smoke a lot, in burning this oil out of the system.

(3) Drain the fuel from the carburetor bowl (drain plug on the bottom of some) OR run the motor (in the water or on muffs) until it dies.  This running would only apply to single carbureted motors.  The reason is for multi carbureted, each of the carburetors may not run dry at the same time, which could create a condition where one cylinder is dry while the other is still running (and lubricating the piston).  For any motor that has a quick couplered fuel line, disconnect it from the motor.  Start it up (using muffs), as the fuel begins to run out and the motor starts to "die", choke the engine a little until the RPM's pick back up.  Continue choking the engine as the engine starts to die out until the fuel supply is finally exhausted.

You want the carburetor empty of any residual fuel, especially now that ethanol gasoline is common, which has the tendency to turn to gum upon evaporation.  If you can not do this then be sure the fuel you are running this last time has been stabilized as mentioned below in #9.

(4) Pull the spark plugs into the plug holes, squirt fogging oil if using that, or WD-40 if running it dry, then pull the starter rope over a couple of times, squirt more, then clean, re-gap or replace the spark plugs.

(5) Remove the lower unit drain plug, just enough to allow it to leak.  Catch a small amount of this oil to verify whether it has any water contamination, which will be in the form of a milky color if contaminated, instead of a golden or black/brown depending on the brand of oil and how much use it has had.  If contaminated, drain it, check or replace your seals and replace the oil.  If it is really black, drain and replace it

(6) Remove the propeller, check and clean the splines.  Grease the shaft with a water resistant grease and replace the retainer nut cotter pin with a new one.

(7) Clean the outside of the motor with warm soapy water, oil or grease any movable metal parts.

(8) If the motor is mounted on the boat using remote steering, check the cables, by moving it both directions, grease the exposed shaft and again move it to allow the grease to be dispersed onto the shaft.

(9) Fill your fuel tank with fuel and stabilize it with SeaFoam and/or StaBil.

(10) If you boat has a fuel/water separator, remove it, check for any debris, or replace it.  When replacing it, fill it with new fuel, which will help on the next startup priming situation.

(11)  If your motor is electric start, disconnect the battery cables, clean the battery terminals using a wire brush.  Recharge the battery to full strength.  You should also recharge the battery once a month during the off-season to prevent electrical discharge and degradation of the electrolytes.

(12) Store the motor UPRIGHT to allow all water to drain out in case your weather turns cold and freezes, breaking metal if water was trapped inside, and not allow water drain back into the engine.

In the photo below you will see what WAS a 1975 15hp Evinrude carburetor.  This was off a motor that was used exclusively in salt water.  The user was not very knowledgeable about boats or motors and stored his dad's motor UPSIDE DOWN for over 15 years.  The white substance you see in the throat of this carburetor are salt crystals.  The choke shaft is free and operational is about all I can say about it.  The motor's pistons were seized, and everything under the flywheel were COMPLETELY RUSTED.

Apparently there was some salt water in the exhaust housing at the time of this miss-adventure and when he turned it upside down, gravity assisted this water in running downhill into the inside of the motor through the exhaust ports and then into the carburetor.  Now his brother has inherited this gem and then I get the task to get it running again.  However not with this powerhead.

Here was a salted  1975 Evinrude  15hp carburetor

The one worst time of the year for a boat/motor to fail is the first time out in the spring.  Sure the motor may run fine, but there are other things that may need to be looked at.   One being the steering cables, like being frozen up and you never even thought about turning the steering wheel during your pre-season checkups.  Kind of embarrassing after launching, your vehicle and trailer are being driven off and you can not steer your boat, with the wind blowing you into other moored boats.  This is one time that you really are glad the kicker motor is working then.

copyright © 2009 - 2016  LeeRoy Wisner  All Rights Reserved

Back to Ramblings

Originally stated 06-03-2009, Last Updated 07-26-2016
Contact the author