115 FICHT Knocking Noise

[thetimerman]

I've got a 99 115 HP FICHT motor that runs well but has a steady knock, that follows the rpm when running. I've partially torn it down and see no signs of scoring or abnormal rod wear. The cylinders all have good cross hatch.
I am able to see one side of all the wrist pins - No wear -No play.
I can rotate the crank without any play in the rod bearings. Everything looks perfect.
The only thing I see is an abnormal amount of black sludge (unburned oil?) around the cylinders and in the case.
I thought for sure, by the way it sounded during operation, that I would find a bad rod, but everything looks good. What am I missing?

 

[birdbucc]

Re: 115 FICHT Knocking Noise

I have the same problem and had a compression check done. #1 was 105 LBS and the others were 130. Don't know if I have broken rings, stuck rings or what. Engine runs great and has good power but sounds like a sewing machine.

Did you find what was wrong with yours? Hate to spend $5M for a rebuilt powerhead.....

 

[jonesg]

Re: 115 FICHT Knocking Noise

have you tried seafoam to decarb the rings. Sludge could be the result of blowby settling in the case.

 

[thetimerman]

Re: 115 FICHT Knocking Noise

just an update. Finnally just got frustrated and torn it down completely. Ended up having too much piston clearance on one cylinder with a little scoring that I couldn't see.
Ended up needing a top end rebuild. Runs fine now.