Just how difficult is it to rebuild an outboard?

[CaneCutter79]

1979 Evinrude 85hp V4, model 85995R

I'm told I will probably need to rebuild my motor. The motor is in terrific shape overall (other than my current dilema) and it has lasted for 31 years without so much as a tune-up. No joke! I know the original owner well and they took care of the boat/motor but cannot recall if they ever had motor work done. The only time it was in the shop was for minor carb. work. No tune-up, no changing the impellar, etc. The motor ran in muddy water for 31yrs, had very low hours on it, and I've had it for 2yrs and it's run like a top. It's gone from being used 2-3 weekends a year to 3-4 fishing trips per month.

So.....

How difficult is it to rebuild the motor if I was to do this myself? I've never rebuilt any motor before but I have a few friends with mechanic experience and I myself can be pretty handy at repair. I've done a few things myself to the motor including replacing the head gasket. That did not fix my low compression in one cylinder issue so it's time to see if the rings are bad or if the cylinder/cylinder wall is bad.


I have a repair manual. It references a few tools that I do not have. Is it worth the investment on a few tools, a lot of time and effort, etc. to rebuild this motor myself? I've been told $2,000-3,000 for a rebuild. I really want to rebuild this motor vs. buying another one. Lots of sentimental value with this one.

Any advice or feedback is much appreciated.

 

[levi_tsk]

Re: Just how difficult is it to rebuild an outboard?

why? is your compression shot? you may just need a good decarb ?

 

[CaneCutter79]

Re: Just how difficult is it to rebuild an outboard?

why? is your compression shot? you may just need a good decarb ?

I made a mistake (not knowing better) and reved the motor up with the prop engaged (in gear) with the water muffs on and not in a test tank. I learned after the fact this was a bad thing. I did it just to see if I could get the RPMs up with the prop engaged. Looking back I could kick myself. I just didn't know any better.

After that, the motor is harder or slower to turn over on the one cylinder. I had an elelectrical problem later after running the motor for at least a month afterwards, and stumbled across my compression issue. I tried to replace the factory original head gaskets on the one cylinder and that did not help. After getting the head cover off, I found the bad cylinder had water damage (washed cylinder wall, polished & almost shiny). I was told as long as the cylinder stayed at 80psi, it should last. I tested the cylinder again after replacing the head gasket and it's now worse. The other 3 cylinders are at 120psi and the low cylinder is down from 80psi to 50-55psi.

I'm hoping I just need new piston rings. If you put a little oil on the cylinder and then test the compression, the compression jumps up to 110-115psi. I was told this is the sign of a bad ring, not a bad powerhead. The motor (on low compression) could run just as fast as it did with all 4 cylinders at 120psi. It was tested at 120psi on all 4 earlier last spring.

If I were to go outside and start the motor, I have no doubt it would take off at it's normal power and speed.

 

[CaneCutter79]

Re: Just how difficult is it to rebuild an outboard?

So how does one pull the cylinders? I'd like to check the rings get the powerhead/cylinders to a local mechanic to have everything check with a mic. for out of round, warped cylinder/block, etc.

 

[wilde1j]

Re: Just how difficult is it to rebuild an outboard?

If you have an OEM shop manual, why not drop the lower unit and replace the water pump with a complete kit. You will need to drop the LU anyway, if you're going to rebuild the powerhead and the water pump is way overdue. 50 to 55 psig is pretty bad. You can try a decarb, but I doubt it will come up very much. The water damage also weighs against an easy, cheap fix. The OEM shop manual will tell you exactly what to do to remove the powerhead, but I'd start with pulling the heads and examining the bad hole.

Then you will have an idea about whether or not you're game for the powerhead. It's not too bad with the right tools and a shop manual, which is quite complete. The first step after a powerhead teardown (keep the parts organized, as bearings, connecting rods, etc. need to go back exactly where they came from) is too assess the nature of the damage and why it occurred (or it will surely happen again, and not in 31 years). A decarb will often help a slightly low cylinder, but not a badly worn or scored one. The next step after teardown is to assess what's reusable and what's junk, then take the block to a MARINE machine shop for them to determine what oversize to bore to, then buy the parts and tell the shop what pistons you will use. Since you don't have any experience, you will need help in determining what to reuse.

If you can follow directions carefully, the process isn't that tough. An alternate is to buy a rebuilt block from a reputable rebuilder, where they do the most challenging steps for you.

 

[CaneCutter79]

Re: Just how difficult is it to rebuild an outboard?

I had a tune-up done last spring where the motor was checked thoroughly and the water pump replaced. He said it actually looked pretty good considering it was the original!

The cylinder wall is not damaged that bad. It looks clean and a little washed compared to the other cylinder walls.

 

[wilde1j]

Re: Just how difficult is it to rebuild an outboard?

50 psig is poor. If you can't get it up with a decarb, rings, by themselves, are usually a waste of money. The final arbitor is a bore micrometer on the hole to determine whether it's within service limits. What it looks like is no help here.

 

[CaneCutter79]

Re: Just how difficult is it to rebuild an outboard?

I was told that I needed to raise the motor all the way up, poor in a little Seafoam and let it sit for a few hours. Then connect the motor to the water muffs and crank the motor.

Is that the best thing to do and then re-check the compression?

 

[jonesg]

Re: Just how difficult is it to rebuild an outboard?

New piston rings have never fixed water intrusion problem, I'm not convinced your analysis is correct.

Revving up on a hose will not usually cause the problems you have,
the danger is the motor could over-speed and run away and throw a rod thru the block.
You didn't post the rpms you ran it at.

You also failed to address Levi tsk suggestion to do a decarb.
You may have just a stuck ring.

And I think you've gotten bogus advice.
If 3 cyl's are at 120 and one is 80psi, thats way out of factory spec and bound to fail with a nasty snap.

Did you test the cyl head for warpage on a sheet of glass when it was off?
And have you decarbed it yet?

I would take a guess at an overheat, warped head and maybe a stuck ring, all simple fixes.
Order the shop manual from www.outboardbooks.com
order a water pump kit . Water pumps can last 5 yrs, 31 yrs is outboardcide.:facepalm:

 

[CaneCutter79]

Re: Just how difficult is it to rebuild an outboard?

31 yrs is outboardcide.:facepalm:

Yes, I know. That's why I had the motor tuned-up and a decarb. I did this last winter with my local marine mechanic. He said it was pretty bad on the carbon deposits. I'd guess so after 31yrs. The water pump was replaced, linkages adjusted, timing checked, etc.

Motor ran fine after tune-up.

I reved the motor up to about 5,200 rpm in my drive way while connected to water hose.:facepalm::facepalm: It was a very short surge and then I let off the throttle. Just wanted to see if it could get over 5,000 because it wouldn't while on the water. It was the biggest brain-fart of the century......I know now how stupid that was.

After this occured, that's when the motor began to turn over strangly. The motor hesitates on the one cylinder. Kind of a "na-na-naaa-na-na-naaa-na-na-naaa" sound if that makes sense. I didn't think much of it at the time and ran the motor for another 2-3 months before checking compression and found it to be about 75-80psi. After replacing the gasket, it went to 50psi.

I poured Seafoam into the cylinder hoping it would loosen the ring but it has not worked so far. I have not tried the "glass" test. Didn't think of that.

I will most definately look at these things before having a rebuild done. So if the head does not sit completely flat on a sheet of glass, it's bad?

I torqued the head bolts in the pattern shown on the owner's manual and to the manual's spec on torque.

 

[CaneCutter79]

Re: Just how difficult is it to rebuild an outboard?

After looking at my "troubleshooting" portion of the repair manual, I may have multiple things that have added up that can explain the issues I'm having. The bigger question is, what do I do?

Overheating
I have had a leak since the tune-up (literally happened imediately after) at what I think is the main seal (below flywheel). Fuel/oil mix is leaking out at the top of the motor from what I can see. According to the manual, this can create overheating issues and lack of lubrication to the cylinder. This could mean a possible main bearing failure or simply a leaky gasket. The last time the motor was running, I heard a knocking that I have not heard before so I'm leaning towards a bad main bearing.

Sticky Piston Ring
Either the piston ring has gone bad or it's sticking. This helped scald the cylidner wall but I do not think the clinder wall will need a rebuild yet. I will definately have it checked with a mic to be sure.

Warped Cylinder Head
I have not checked for this yet (it looked flat to me and I set it on a flat surface but not glass)

Sounds like I need to try a decarb once again to see if that increases the compression. If not, disassemble the motor and check the rings, cylinder, and powerhead. Check the main bearing and see if it needs to be replaced.

Does this sound like the right direction to start with?

 

[Outsider]

Re: Just how difficult is it to rebuild an outboard?

Rebuilding is easy. Rebuilding correctly, a whole different animal ... :redface:

 

[levi_tsk]

Re: Just how difficult is it to rebuild an outboard?

sounds like your on the right track BUT i think you broke a ring and or fried a rod bearing or a wrist pin....
for future reference its a VERY bad idea to rev your motor if it isnt running right and you really shouldnt rev it at all out of the water
this sounds like you needed a carb rebuild to start with due to the fact that it wouldnt accelerate under load and because of this i think you ran lean on that cylinder and that would cause the suspected damage
motors of any sort dont do well when they sit up unused for years and years on end and are then asked to perform at tip top opperating parameters its a recipe for serious mechanical failure
so to those of you lurkers out there DO NOT AND I MEAN NEVER let your engine sit for over a year and then take her to the lake and ask or even expect your engine to run right because this^(up there) is what WILL happen
a simple carb rebuild would have let this one live another 31 years

cane cutter decarb it and

if that doesnt help check the head(s) for flatness if its out of wack you can use some 240 grit wet or dry sandpaper to bring it back into flatness to an extent but anything 1/16" and over is gonna call for a new head

if the head looks good tear it down youll have to take the whole block apart to get the piston out my moneys on a busted ring or two and hopefully you dont have any bearing failure BTW most of the time a knocking sound from any engine i from the reciprocating assembly(pistons, rings, con rods, and wrist pin) not the rotating assembly( main bearings crankshaft....) might have done a wrist pin and the rings this would explain the dead cylinder and the knocking and since from what i understand the wrist pin is the weakest link in the recip assy
also dont be too freaked out because after all its only running on 3 cylinders the sound unless its a clunking one may be from it not firing like it should

 

[1946Zephyr]

Re: Just how difficult is it to rebuild an outboard?

Why would it cost 2 - 3 grand to rebuild it?? I could rebuild a Ford 460 for about half that and it has 8 new pistons, versus 4. I would do some research. It shouldn't cost that much to rebuild one of those. If it does, tell them to take a walk.

I think one problem with these V-4 models, is 50:1 is not quite enough oil for these, since they run at higher rpms a lot. It's not like grandpa's old 10hp that putts around the lake. These bigger motors work hard most of the time, even after sitting for months. I personally would put 32:1 mix in a motor, like this.

Oil is the cheapest thing you can put in a motor.

 

[emdsapmgr]

Re: Just how difficult is it to rebuild an outboard?

If you are mechanically inclined, you should be able to overhaul the engine. I'd start with getting the original factory service manual from Ken Cook Co., in Milwaukee. That's the only one to use when doing this type of work on an OMC engine. You will be looking at 4 new ringsets for sure, perhaps at least a new piston, depending on how the cylinder walls look on the low compresssion cylinder. Not unusual for older engines with lots of hours to wind up with some powerhead noise-called piston slap. Not uncommon. You'll determine if the powerhead need boring and if the pistons need to be replaced when you get the powerhead torn down. Boring all 4 holes and new pistons will cure that noise. You'll need a factory powerhead gasket set 389556. That will come with all the new seals and gaskets that you will need. It's always possible that you will have to bore one or more pistons oversize, depending on the cylinder wall taper and out-of-roundness with years of use. You can overbore just one cyl on an OMC, leaving the others standard. Factory oversize pistons weight the same as standard pistons, so stick with factory replacements. You will need special gel sealant when you mate the crankcase halves together, so follow the service manual closely when you do this. Check the internal bearings and crank surfaces for blue color, which will indicate overheating and lack of lubrication. That's usually a pretty rare situation. Water leaks can be from a bad head gasket or from exhaust chest leaks. Both issues should resolve themselves when you put new head gaskets and (two) exhaust cover gaskets on the engine. You will need to replace both thermostats and visually check the nylon pressure relief valves in the thermosat housing. The original factory fuel lines on that 79 are not rated to handle today's ethanol fuels. You should replace all lines with new (use the same original factory part number hoses) lines-the old hoses will deteriorate and small pcs of hose can lodge in the carb jets, causing lean conditions. (I'd add an inline white plastic fuel filter in the 8' fuel hose from the tank.) You will also need two carb overhaul kits 439076. Your overhauled stock engine should wind up with compression in the 125+ range after break in. It all depends on how much money you want to put into the engine. If this engine is of sentimental value to you, spend the money. Compare your overhaul costs vs a new engine..... It will run like new when done.

 

[stackz]

Re: Just how difficult is it to rebuild an outboard?

why not look around online and see if you can find a rebuilt powerhead cheap. I see rebuilt ones for 200hp engines on ebay for $1000.

then use that powerhead while you tear down and inspect/rebuild your original one. then you'll always have a spare until you decide to sell the engine outright.

 

[jbjennings]

Re: Just how difficult is it to rebuild an outboard?

I like the last 2 posters advice in particular. With compression that bad and knocking noises, the only thing that will fix this motor is a rebuild. You really need a book to do it, and write yourself a step by step check list for reassembly. You'll find that tearing it down is VERY easy. But there are a few little things that need to be done right on reassembly like orienting the rod caps, torquing the rod bolts, positioning the rings correctly, checking/boring the cylinders. With the book, it shouldn't be a problem. Make sure you also check to make sure your fuel pump, tank, and tank hose and such are perfectly clean, along with a spotless carb set. You don't want to crank it for the first time after the rebuild and get crud in a carb from dirty lines or dirty fuel pumps, causing it to run lean.
Rebuilding or used powerhead sounds like the only options to me. I personally would be somewhat leery of a REBUILT powerhead off ebay for too cheap, since it takes money to rebuild one, although you might get a great deal, too. I'd probably go with a used one with good compression. ONe I rebuilt myself would be nice, too. Sometimes if you're lucky, you can find cheap pistons and cranks and rods and such on ebay if you need 'em.
Good luck,
JBJ Btw, if you rebuild it, I'd enjoy some pics. I rebuilt a '72 50hp recently and finally got it running right and it really idles nicely and runs smooth. A v4 rebuild would be nice to see.

 

[Tim Wagner]

Re: Just how difficult is it to rebuild an outboard?

You have to be a bit savvy with being able to fix stuff.
But, I did an 85 two stroke. The pistons were all roasted and trashed the block.
I found a good block on ebay
bought 3 new pistons and rings.
Bought a gasket kit.
I think all in all, I spent about 450 bucks in parts.
I set up a nice well lit workbench in the middle of my garage and went to town with baggies and such to tag the bolts and other items with as I tore it down.
Once it was all apart, I did some typical prep work, cleaning this and that.
Then i went to town slapping it all back together.
For me, it went quite well and very smooth.
Once I got it back on the motor and all reassembled, it started right up.
I had to do very little "tweeking" when it was ll over.
In fact, after i finally went through all the double oil, break in time and changed the plugs.
I start it up and after a long run and a stretch of fishing on the foot control, I hit the key and it fires right up without screwing with the fast idle or anything.
Id do it again if needed. I was quite pleased with all the results.
Plus, a two stroke is a teeny bit "forgiving".

 

[wilde1j]

Re: Just how difficult is it to rebuild an outboard?

BTW, pouring SeaFoam in a non running motor does nothing. Sea Foam depends on lots of heat of combustion to do it's thing. You soak the motor for a year in Sea Foam and it would not do much. See sticky about 'decarb". As pointed out by emdsapmgr, you need an OEM shop manual, not a third party beer coaster. If you proceed slowly and carefully, asking questions as needed, a rebuild is not that bad. But you need to already know the basics of proper tool use, like using a torque wrench, etc. I had the advantage of a very skilled person (my Dad) when I did my first major rebuild in the winter in an unheated garage in Mass in the early 60's. It was a '57 Evinrude 18HP that was still running fine 25 years later.

 

[levi_tsk]

Re: Just how difficult is it to rebuild an outboard?

third party beer coaster is a damn good description of a clymer or seloc manual i inherited one from my dad -completely USELESS !!!!!! in fact i dont even know where it is right off ... go on ebay and get a used service manual for your year model mine was only about $25 shipped which is right in line with one of those beer coaster useless p.o.s.'s