Should I fix it?

[dsujen]

Should I rebuild a 1987 90hp johnson? What will it cost me in parts? It currently runs but has some aluminum transfer to cylinder wall in cylinder 3. And compression is off. How hard is it? I have tools and am pretty good at working on things.

 

[flyingscott]

It will probabaly need to be bored out about $70 a hole by me might be different by you. If it's me I would do them all so $280 for that. They have complete rebuild kits on ebay for $775 but for that motor upgrade to the wiseco piston they are much better than the oem one. You will also need a factory service manual. Except for the boring of the pistons unless you have that experience, you absolutely can rebuild your motor.

 

[emdsapmgr]

These older crossflows are an elegantly simple engine. Agree, get a factory service manual-only. They have great pictures. You can do the overhaul yourself. It is perfectly ok to overbore and replace just one piston, assuming the others are still ok. Plan on all new ringsets, however. You'll want to know just what caused the failure. Such as debris inside one of the carb jets that feeds the bad cylinder-causing a lean condition and subsequent failure. You can dissolve the aluminum that's transferred to the cast iron cyl walls with some muratic acid. It won't hurt the cast iron and will clean up the cyl. Then hone it, if it's not too far out of spec (egg-shaped._

 

[gm280]

Oh man, that would be a great project if I had it. But you have to make the final decision as to whether you want to tackle it or not. Nobody else knows your abilities and therefore we can only offer support if you decide to rebuild it. If the engine looks decent, I would rebuilt if. But only after buying the Manufacturer's engine, year, model specific shop manual for it first. That IS the best source for any questions you will ever need.

 

[flyingscott]

The only thing I would say about replacing only the rings and one piston is this. Those crossflows are notorious for breaking rings because of the ring design. By going to the wisecos you eliminate that design an i believe will gain better reliability for the motor. That topic has been covered here quite a bit about the cross flow ring design and it's penchant for breaking. I also really like wisecos if you are only going to hone the cyl because the hole is already oversized from normal wear. Wisecos need a slightly bigger bore than a cast piston so tend to fit better in a worn hole. But in the end it's your motor.