Piston head damage

[astampfel]

I have a 90 Hp outboard Johnson, VJ90TLESB. One day I overheated my engine after my water pump failed. I replaced the water pump and the engine ran fine. About 2 trips later though, my engine ran sluggishly and rough, like a cylinder wasn't firing. I hooked up my compression tester and #1 cylinder had zero compression, #2 had 110 psi, #3 had 90 (with water in the cylinder), and #4 had 105 psi. So, I took of the starboard head since the problems were on that side. See the attached pictures. #1 piston has a lot of pitting and carbon buildup, while #3 cylinder and piston look fine. If I run my fingers around #1 cylinder, I can feel slight wavy grooves all the way around compared to #3 cylinder that feels smooth/flat. #1 piston also has noticable side to side play where #3 has not as much. So, I'm open to suggestions on what to do.

 

[HybridMX6]

Re: Piston head damage

Need to retry the pics, none are attached.
Sounds like it chewed up a ring though, but pics of the parts in question, the head from that side, and the gasket if it's still in viewable condition, will help us out.
Any way, sounds like a rebuild is in order, and the parts and cost to do it all depend on the condition of what's left in the motor, and if you want to spend the money on it.
You're not far from me, btw. I'm in Winter Park/Casselberry.

 

[astampfel]

Re: Piston head damage

I've included some pictures of the gasket as requested. I also added one picture of the cleaned up head with the gasket off.

 

[HybridMX6]

Re: Piston head damage

That looks like it chewed up a piston ring to me. The head gasket doesn't look terribly bad, but you can tell (at least it appears so) where it leaked. Overheating the motor may have warped the head, causing that head gasket to fail. In any case, you will need to pull the powerhead off at this point if you intend to rebuild it yourself, or take it to a shop and have them do it. I'm not familiar with prices on larger motors like these to rebuild. I rebuilt a 3cyl a year or so ago and spent $1200 in parts, and did it myself, but it needed a lot more parts than crankcase stuff, it was a very neglected motor and needed LU work and all as well. I think I probably spent $700 or so on just the powerhead rebuild parts, and machine shop labor to fix the cylinders.

 

[mrcj001]

Re: Piston head damage

The exact same thing happend to me......piston broke off a piece of a ring. Chewed up the piston and head.

I have noticed these crossflow engines do this alot.

I just repowered the boat with a good used engine.

Try Crieg`s List in your area.

 

[astampfel]

Re: Piston head damage

Thanks for the advice. I think you're right about the piston ring. Do you think it failed because of something I did, or just because it was old? Anyhow, I purchased a used engine, 115 Hp Johnson (same style as my old one just more Hp) for $900. It does look used, but I just hooked it up and it runs. I have to see if the voltage regulator will charge the battery and if the VRO works.

Andrew

 

[nymack66]

Re: Piston head damage

I am not sure how many hours on those plugs, looks like you ran this motor on the lean side hence the ring failure.

 

[surrender]

Re: Piston head damage

The exact same thing happend to me......piston broke off a piece of a ring. Chewed up the piston and head.

I have noticed these crossflow engines do this alot.

I just repowered the boat with a good used engine.

Try Crieg`s List in your area.

Cross Flows breaking rings? Never heard of that being something to watch out for on these motors. looks like a lean running condition caused the failure. If my plugs looked like that i would have been sure to figure out why.