How bad is this gonna be?

Well after getting everything straightened out and putting the final tune-up on the motor(OMC 2.5,120 hp, 4cyl) still had a miss. not that bad but I know it's there. New plugs,cap,wires,rotor,condenser,points. #2 cylinder is way down on compression. Just barely blows your finger away from the hole. I pulled off the valve cover, Lash is good,no bent pushrod, both rockers are moving like the others so the cam in not wiped on those lobes,no broken springs. The engine runs fine,except for the little miss. 45lbs. oil pressure,temp. is good at 160-170 and. I hate to put anymore money in her. Should I run it the way it is for this year and be down a little power? My wife and I are just useing it to do some cruising, not gonna pull skiers and tubes with it and abuse it. I'm really beside myself about this. after all I've done to it it's got a bad cylinder now. thanks for any positive help guys

Re: How bad is this gonna be?

You've got to do a leak down test to be absolutely sure on what the problem is.

https://www.youtube.com/watch?v=WgrfT0LFMhc

Re: How bad is this gonna be?

Could be something like a bad valve seat. That would blow your compression easily, especially if it is the exhaust seat. The intake would blow back into the intake and you would probably hear it, but an exhaust seat would go undetected for the most part... Just a possible "could be" suggestion...

Re: How bad is this gonna be?

compression test then pull the head. look for a burnt valve or crack in the head gasket. if its still a small leak the old trick use to be to turn the head over with the valves shut then fill with diesel or parafin and leave for a while then come back and if the diesel has drained then the seat/valve is not sealing or theres a micro crack.

Re: How bad is this gonna be?

Forgot to mention that when it's at a low idle, and I give it gas it will like pop,pop,pop, out of the carb until it gets past that point.

Re: How bad is this gonna be?

Sounds like a bad intake valve,you'll have to pull the head and have a closer look.

Re: How bad is this gonna be?

Had an old dhevy do that, I could hold my finger on the side of the valvespring with the motor running, it would stop missing. Valve guide was sloppy,valve not far behind.
Grub

Re: How bad is this gonna be?

Gave it to my friend who is a marine mechanic, and he's gonna pull the head off and send it out and have it done. No sense in putting on a used head, it may be in the same condition as mine.

Re: How bad is this gonna be?

Ok , it was a blown head gasket. I'm glad it was just that. I still had him send it out to make sure it's straight and freshen it up though. I guess I'm lucky nothing was broken .

Re: How bad is this gonna be?

footbrake said:

Ok , it was a blown head gasket. I'm glad it was just that. I still had him send it out to make sure it's straight and freshen it up though. I guess I'm lucky nothing was broken .

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great news glad you got it fixed before it became a real problem