76 evinrude 85 horse won't do anything

[kofkorn]

You can pull the heads and take a good look at the condition of the cylinders. At this point, you're going to have to really think about how much time and effort you want to put into this motor. Doubtful that those numbers are due to head gaskets.

Take the heads off and take some pictures. If there are significant axial scores/scratches, you will need to do a complete rebuild.

 

[rodknee1231]

ugh. I'll check the reeds too maybe ones broke or something. I I did want to ask you guys if I can use a 79 year gasket on my 76 they are a lot cheaper and look the same

 

[Pappy]

No....that head gasket will not work on your engine. Two different cu. in. engines. Yours is 92 cu. in. and the 79 is 99 cu. in.

A cheaper way to inspect is to remove the intake by-pass covers and have a look. Gaskets are alot cheaper. These covers are the ones on the outside of the "V" and usually have things like the starter solenoid bolted to them.
You should be able to see the top of each piston to see if they are burned and also see the cyl. walls and piston skirts to look for grooves and scuffing.

 

[rodknee1231]

ok I'll give that a shot

 

[rodknee1231]

the reason I think head gasket is that one side has lower compression than the other and the gasket on that side looks newer so I'm wondering if it was done wrong or something

 

[rodknee1231]

View attachment 1View attachment 2 this is the cylinder with the lowest compression the gasket was definitely old but that piston is done. exactly what I was hoping I would not find.

 

[Pappy]

Okay, now it is decision time.
What I will tell you is that, overall, the 92 cu.in. 85hp is one of the best running, most durable "big" engine ever produced. They are normally very hard to kill.
We had that engine on test boats and would run them a full 500 hours at WOT for the most part. Jumping surf, the test drivers told me they just let the 85s eat and never feathered the throttles.
At the end of the 500 hour endurance cycle the powerheads were torn down, measured and put back on test for another 500 hours, with the same rings, until the end of the test was reached. Those engines just would not give up.
They have incredible bottom end torque and flatten out like a pancake around 4000rpm. Great ski engine. Economical to run.
If it were mine I would bore to oversize, install 4 new pistons, rings, and a gasket set.

 

[rodknee1231]

I'd love to but I don't think I have to cash. but that means I run the risk of siezing it or blowing it up. if it were you on a minimal budget what would you do

 

[rodknee1231]

I will say the other side is spotless looks new

 

[Pappy]

You are only looking at the intake side of the pistons....the cool side.
But, you should be able to look at the cylinder walls on the exhaust sides with a good light and see what kind of shape they are in.
Lets say it overheated. (You will be able to tell once the cylinder heads are removed by looking at the water diverters).
The exhaust sides will be the first to go, then if the owner does not recognize what is happening fast enough the build up of material coming loose from the exhaust side will build up and force the piston over toward the intake side of the cylinder and damage occurs there as well.

 

[rodknee1231]

yea unfortunately I can't see the cylinder wall the piston does now go down far enough.

 

[rodknee1231]

I take that back. I can see the exhaust side walls they are not perfect but much better than what the piston looks like on the intake side you can kind of see it on here

 

[rodknee1231]

and of course the impeller is disintegrating.... I'm gonna run this motor then rebuild in a year or 2 When I have the cash

 

[Pappy]

Do not spare the oil if that is your decision. Run it rich.

 

[rodknee1231]

what do you suggest I run

 

[Nubbins]

Pappy is 100 percent right in what should be done on this motor. Everyone who I've known that has had one and doesn't own it now compares everything they've had and have to it. You asked the question minimal budget. When you say that there are risks with short cuts. That being said I have had many successes and a failure in my dealings with outboards. All major work I've done has been on mercury. Generally what what you have on the cyl walls is build up from the piston. (Alluminum) I can't really tell what the rings look like. I have removed the pistons. Carefully honed the the cyl to remove the build up. Not the grooves or scars. Slide the old ring In the cyl and look at the end gap and measure top of ring travel and bottom. The pistons seldom can be cleaned up if there is much scaring in the ring land area. I've always be able to find used pistons with a little looking or just replace the worst ones. If the end gaps look good, cyls aren't scared up real bad. Put a set of rings and gsks in and give it a go. It won't be like new but I have gotten good life out of the ones I've done. The ones I know where they are are still going great. This works well with tn 2 stroke engines. 4 stroke is probably a different story. I've done mechanic work for 30 plus years so much of this is feel for what can be used or not. Engines usually have a min and max specs on clearances allowed if you can find them. Pappy is right in his call on this motor, and be it mine and my situation right now money wise his call would be the way I'd go. But there has been times I've done it as outlined above for money reasons. You asked for a minimal budget suggestion this is mine. Hope it helps

 

[rodknee1231]

yea the thing is that the piston is bad but the rings don't really look scared at all. so your saying I can probably get by with honing the cylinders and replacing the piston without boring over.

 

[Pappy]

The third photo down of the set you took with the by-pass covers off.
That photo clearly shows rings that are mechanically stuck (with debris). Farther around I can see the same rings are stuck with carbon which can be treated. The mechanical sticking cannot.
What you have to remember here is that you are working with a 2-stroke. It will produce power and heat with every revolution and as such it has to get rid of the heat much faster. If this is not possible then the engine will leave you out on the water at some point.
If you do the work yourself the cost of new parts is not prohibitive. Pistons, rings, new rod bolts, gasket set, gel seal are the main ingredients plus some gasket sealing compound.
Purchase a service manual and go over it to the point you are comfortable with knowing the NEXT step that is coming up in a rebuild, rebuild it, and the engine should provide you with years of good service.
If you decide to run it as is I am afraid you will be pretty much on your own.

 

[rodknee1231]

I agree I'm gonna just wait till winter and do it all. is there any good rebuild threads on here I can't find a whole lot on Google

 

[Nubbins]

Hope when my computer returns I might be able to view the pics better. This phone isn't all that