92 OMC 5.8L low compression on cylinder #3 and #7

[cheers731]

Just learned from the shop that my 92 OMC 5.8L has low compression on cylinder #3-100 psi and #7-30 psi. I can't figure it out how it happened and what to do next? Can anyone shed some light on how to troubleshooting on bent valves, leaking gaskets, piston rings or something else for repairing?

Many thanks to your input.

 

[Howard Sterndrive]

Re: 92 OMC 5.8L low compression on cylinder #3 and #7

do a visual inspection on the valve springs and valve train. Try valve adjustment if everything looks fine.
You're asking for tips on troubleshooting the cause of dozens of issues you *may* have. Do a visual and then focus on the issues you actually have.

and if it's in the shop, you'll need to decide who is fixing it. The threads where iboats members play "second guess the tech" tend to go south pretty quickly. Internet troubleshooting the what if's is fun for some - so I don't want to stop the dozens of "on my boat it was the _______" responses, but a visual is first - from that decide if the head is coming off for further inspection. .

 

[HT32BSX115]

Re: 92 OMC 5.8L low compression on cylinder #3 and #7

Just learned from the shop that my 92 OMC 5.8L has low compression on cylinder #3-100 psi and #7-30 psi. I can't figure it out how it happened and what to do next? Can anyone shed some light on how to troubleshooting on bent valves, leaking gaskets, piston rings or something else for repairing?

Many thanks to your input.

Howdy,

I'll "ditto" what Howard indicated above... And add, that once you determine that you have compression problems that cannot be "adjusted out" (by adjusting rockers, valve lash etc...............

The only next step is removing the head(s) to inspect, repair, replace etc.


Once the heads are off you can speculate on what caused the above problems.

 

[cheers731]

Re: 92 OMC 5.8L low compression on cylinder #3 and #7

Good point. Yes, will remove the valve covers first do a visual examination.