New engine break-in popping in exhaust - 1992 Mercruiser 350, 4bbl

[incrediblened]

I just installed a new remanufactured marine 350 motor in my 1992 Sea Ray. I've got the engine timed at 10'BTDC at idle. It starts and runs and I'm in the 10 hour break-in period.

I'm noticing some popping in the port side exhaust. Do I have a valve set too tightly and maybe I'm getting ignition in the exhaust?

The popping seems to go away at higher RPM's, but maybe that's just because I can't hear it.

Any thoughts? And any additional tips on breaking in the new motor?

 

[cr2k]

Re: New engine break-in popping in exhaust - 1992 Mercruiser 350, 4bbl

Try re adjusting the valves. With it running: (oily mess) Back off until clatter slowly tighten until quiet and the book sez 3/4 turn in slow 1/8 turn increments.

 

[incrediblened]

Re: New engine break-in popping in exhaust - 1992 Mercruiser 350, 4bbl

I just readjusted the valves. Slapping still present. Is it possible that the backflow prevention flaps are slapping around in the exhaust manifolds?