787 motor / 2004 3D rfi

[johna56]

I'd like to avoid the dealer's mechanic but im not sure what to do here, any suggestions that have to do with diagnosing the the machine would be welcome. I realize there may be a couple issues.

Engine and mpem have less than 20 hours on a rebuild by former owner (a sea doo tech). Engine runs fine for 10-15 minute, then the plugs foul out. Smoke in accumulating in the engine bay, but i can't see from where. More than the usual amount of water is collecting in the engine bay. It has new battery and rectifier seems to be operating properly (friend familiar with two strokes came over with multi meter and checked). Compression from cold is 125 in the front and 135 in the rear cylinders, respectively. Compression after warming up on the water was 120 in the front. Rear was not checked because i was under the impression compression should be higher after warm up. Any thoughts here?

 

[mikidymac]

Compression should always be checked cold.

I would try a different compression gauge as perfect compression is 150 psi and at 120 the engine is done and needs a rebuild. THe 10 psi difference in cylinders is concerning also.

For the fouling plugs, you have an exhaust leak in the engine compartment which is starving the engine of oxygen and fouling the plugs. Seeing as how you have water also I would suspect either an exhaust gasket or the welded welch plugs on the pipe have corroded through.

 

[etemplet]

Sure sounds like shoddy workmanship to me. You have all kinds of issues you shouldn't have.

 

[johna56]

Thanks for the replies. Seems like there are several things going on here. The last full day we got out of it in 2018 - we rolled it, but (i think) rolled upright the correct way and continued riding it for several more hours. It seemed fine that day. It always was cleaned and flushed, and fully winterized. Near as i can tell, best case scenario is compression is off due to gauge, exhaust has leak, and bilge pump isn't working properly. Worst case is I need a new engine (or rebuild), and a bilge and a bunch of stuff cleaned. The 3d is really a back up ski and i prefer to keep it because of its different uses and I chose the 787 over the 951 b/c it was supposed to be more reliable. I guess ill run it to the dealership and see what they say, make a decision after i get the full slate of issues.