semi bad news 1992 Evinrude VRO 90 HP what to do? pics

[scmutiger]

I finally checked the spark and compression myself. The good news is that I have great spark, and great compression on 3 of 4 cylinders. The bad news is obviously that I have weak compression on 1 cyclinder.

*around 115 on 3 good cylinders -- 80 on the not so good cyclinder*


The previous owner mentioned that he had some overheating problems in the past. It looks like the head gasket might have leaked. It sure would be great if I could get away with just replacing the head gasket. The plug in that cyclinder looked the same as the others -- black/wet with oil.

What would a shop normally charge to replace one head gasket? What would they normally charge to install a new ring? How hard is it to install the gasket and ring (I am waiting on my manual).

Should I try running SeaFoam in that cylinder since this motor runs very well on the muffs?

Thanks,
Scmutiger

[wilde1j]

Running on the muffs tells you almost nothing, other than the motor runs. Decarb by mixing a can of Sea Foam or Engine Tuner with about a gallon of gas in a remote tank. Fast idle the motor until the mix is all gone. Let the motor sit for a few hours and start on the normal gas / oil mix. That's it. Then recheck compression.

Replace a head gasket ... about 1/2 hour of labor plus the gasket. Not too bad.

Replace a ring set, plus bore one hole and replace the piston for that hole ... a lot of money (the block needs to be completely torn down and re-assembled). Over $1000, probably more depending what's found on inspection.

[tashasdaddy]

the only way to know is to pull the head, not a bad job. then you can see whats, what.

[Reggie08]

I just rebuilt an 85 'Rude 90hp. Different years I know, but the blocks are very similar. It was a rather easy process. A little time consuming but fairly easy. If you're the least bit mechanically inclined, you shouldn't have any problem opening up the powerhead and replacing that piston and/or rings. To get to them, you're going to remove the carbs, intake then open up the crankcase. If everything goes as planned and you don't need any machine work done on the cylinder, you could probably get it done in one day. At the most, a weekend. You'll save tons of money.

In the interim, open up the bypass cover on the side of the motor and have a peek at the piston/rings with the low compression. You won't see the entire piston but it might give you an idea if the rings are worn down and if there's any damage in cylinder.

As for the head gasket. That's another very easy task that could probably be done in an hour or two. My suggestion first though would be to decarb the motor then check the compression again to see if that cylinder comes back up.

[SKEETR]

I agree. Pull that leakin head gasket. It is possible the #3 piston rings are just gummed up and not sealing well from mixing with water. You could also pull the bypass cover off to visually inspect the rings to verify if they are both there. At least you are dealing with the more accessible side of the engine. I wouldn't bother with the seafoam until you inspect the cylinder and replace the gasket.

[scmutiger]

Does 80 pounds on that top cylinder sound like a leaky head gasket? I would expect water/steam to be cleaning the spark plug with a blown head gasket, but it isn't. From looking at the pics, does it look like steam bubbled away the paint on top of the motor to you? It does to me, so I am definately going to pull the head just to be sure just as you suggest.

I am going to try a SeaFoam shock treatment while waiting on my gasket to be delivered.


Thanks,
Scmutiger

[scmutiger]

I pulled the head ---

It looks like the overheating caused damage to the top of the piston, and some to the flat part in the bowl of the head. The cylinder wall had a little rough spot too. I am going to pull the power head next weekend, and try to do my first ever rebuild. Does anyone know where I can get a used/new/replacement head for a 1992 VRO 90 HP Evinrude?


Thanks,
Scmutiger

[wilde1j]

Try this website.

[tashasdaddy]

http://shop2.evinrude.com/ext/index....cfd8a6471c0f7f