97 Mariner 125 Compression issues

quikstang347 · #1 January 22nd, 2009, 10:09 PM

Hello to everyone on this site i am newly registered here but have been reading the forums for years.
I have a question to pick your brains,
i just recently purchased a 19' trophy center console with a rebuilt 125 mariner on it. Yes i have the paperwork and talked to the marina that did the rebuild to support this. my question is that i took the boat in for a basic check up and a new impeller to be installed. once i got the boat there i wa stold i had the following compression readings
#1 130
#2 20
#3 130
#4 130
the only issue i have with this is that i took the boat out and it ran fine. ran 5500 rpm no problem no noise no issues ran at 40 mph. all of a sudden i throttled down due to an on coming wake and the boat died and would not restart. got it towed in and the next morning still the same . pulled al of the plugs and changed them (carbon fouled) thought it would start and no go. next i pulle dthe carbs and cleaned the jets reinstalled and walla it fired and ran fine. that is when i took it to the marine mechanic, this is a reputable shop but a small one. i am just wondering with a boat engine that has sat up for a while is there a special way to reintroduce it to being used. the motor was rebuilt with all new pistons new everything. #1 and #2 were sleeved and bored .030. the mechanics say i most likely have a broken piston. but with no damage on the plugs this si hard for me to believe. i am no boat mechanic at all. the motor is a 97 125 the case has to be split for the rods and pistons to come out. this is a lot of work for a diag that may just be stuck rings. is there any way i can tell before i authorize a large repair bill. i am an ase master tech for automobiles but know nothing about outboards. thanks for all the help in advance it is greatly appreciated.

p.s.
the impeller was wiped out no peeing from outboard at idle only while moving. would #2 overheat before the rest of the cylinders. thanks again

quikstang347 · #2 February 7th, 2009, 06:06 PM

stuck ring on #2 needs a new piston it was from overheating .

Faztbullet · #3 February 7th, 2009, 06:45 PM

I would like to know why if #1 & #2 were resleeved, that they were bored.030 over? Resleeving them would have brought the back to standad size. One cylinder cannot overheat from a weak impeller, ALL will overheat and in a Inline engine #1 & #2 go first. I would check other pistons for scuffing and replace ring on the also.