this is my boat. did a comp check tonight. 125 across all, except cyl #5 i think (port side, 2nd from front). nasty oil leak under the head gasket, enough to drop the comp to 60 psi? hoping so...losing quite a bit of oil. check on saturday before heading out, was between full and add. checked tonight, about 3/4" lower on the dipstick, below the add line...thats only about 1 hour of run time, with at least 30 min of that at idle, and the other 30 cruising, 3500 rev's +/-...

don't run it...pull the head...see whats up...don't think it's just a head gasket...

x2

well, warmed the motor, did another compression. cranked 4-5 times and on the last 2 hit a steady 50 psi. then i squirt oil into the cylinder, 50 then 60 then 70 psi...im F****ed arent i? its only 1 cylinder, but a bad head gasket leak. freakin motor has 30 hours on it, what would cause this? "Allegedly" built by a reputable motor shop out east. if the previous owner will ever call me back, id like to contact the shop and see whats up with the motor. its not a gen VI since its a V-belt...(boat is a 98 though) so i dont know how to find out what year the motor is, but it IS EFI. super dissapointing after only owning it for 6 weeks, already replaced a drive and the funds are dwindling.

Mine has v-belts and is a gen VI motor so there is a good chance your is also. Is there a serial number sticker on top of the ECU housing or plenum? The SN was also stamped on the original drive if you still have that. If it doesn't have a man. fuel opening on the side and the timing chain cover is cast aluminum, that makes it a gen6 motor. That doesn't realy help or change the situation at all. If the compression is going up when you squirt oil in the cylinder, that is an indication that maybe a ring didn't seat properly, or it broke when it was installed. It sucks, but if you can do a lot of the work yourself it isn't really a big expensive problem. What worries me more is what and where is the oil coming from, and the problems that it may be causing the oil leak. As previously stated, I would pull the exhaust, intake, heads and then go from there.

port side 2nd one back is cyl #3... if you dont hear it popping through the intake then you may have burnt a exhaust valve,,maybe that injector is not up to par?
Don't keep on running it this way,it will only get worse and if it is a valve it may brake off and fall in the cylinder..
your about 45 min from me and i have a boar scope that i can look into the cylinder with to see whats going on.. the oil could be coming from a oil cooler line? or the remote oil cooler line adaptor?? oil pan gasket could have slipped? the oil could be coming from a number of places..

pm me if you want to come over to my shop and see if its something major in the engine..could also be something as simple as a bent or two push rods.