Bad timing, in the heart of the summer. I was trying to go as slow as the boat would go on plane, about 2800rpm and it suddenly lost power and started falling off plane. I pushed the sticks forward, lowered the drives and it struggled back up on plane. Was close to destination, backed down the engines and no waked for about 5min, parked all day. port engine sounded funny on start up but boat ran up to 3500 cruise for 7 miles home. Next day port was popping and not wanting to rev. loaded it and took it home thinking bad gas(I wish) or something. Plugs were sooty 4,6,8 were wet. Comp test was spot on 1 3 5 7 and 2, 4 6and 8 had 20psi or less. Leak down revealed leakage between those cylinders. It being summer, I knew there was no way to get any serious issues fixed in time, so I opted to take a peak with the engine in the boat(oh my aching back). Head gasket was melted between cylinders 8 6 and 4, #6 piston and CC were clean, 4 and 8 looked normal. After cleaning everything up, I may get lucky and can salvage the summer. My question is why was 6 washed? did the gasket blow in the 2 spots and then the adjacent cylinders fuel plus its own fuel make everything clean? or did something happened in 6 causing it to blow into the 2 adjacent cylinders. Heres some additional info. I tested fuel pressure while diagnosing the fouled plug issue 38-40 on prime, idle and as much easy rpms as i could give it. I left the gauge on it( they could have put that shrader in an easier spot) and 2 days later it was still holding 25psi, when i pulled the intake. The Boat is a 2000 Baja 342, the HP500EFIs have 688hrs. This port engine still had the factory seal on the front intake bolt( had to cut the wire). I bought the boat with 603hrs and did valve springs before I ever started it the first time. I have meticulously maintained it for the going on 4 years i have owned it, including a mid season oil change and compression test/plug change every season. I am hoping it is just age, but if there is anyone who has had a similar issue and knows the cause, I would be thankful for the info.

That type of damage can be caused by detonation. Might not be a bad idea to have the injectors cleaned and flow checked.

Personally if it was mine there is no way I would have it pulled down that far and not do the other side too.

Well this is a temporary fix, to hopefully get thru the summer. the compression test on the other side was identical to the one I did pre season. If I had intended to do both sides I would definitely pull the engine, and if your gonna pull one might as well pull the other, and if you got them out might as well do rings and bearings and so on. You guys that do this all the time in the boats are complete animals! Im 58 and this will be the last time lol. I was actually planning to do them this winter. Of course I was planning on last winter too lol.

Mission Creep is an issue at the best of times...it's a nightmare when you actually find more things that need doing...lol.

In this case, I think the suggestion of checking the other head/gasket would be the prudent thing to do. Wouldn't take long...and maybe it was on the way out too...and that would dampen the summer x2.

Do the other side too. If you don’t it will bite you in the ass at some point. If you take it apart and it all looks good at least you can sleep better at night knowing you did the right thing. Really, what’s it gonna take, maybe another hour of your time and another head gasket cost? Good luck.

I assume those are stock un opened. It was a somewhat common problem if I remember correctly. Like other said do both sides and if you have not did springs and seats, do them now.

I understand you want to get back out but a failure on those and you will have bigger issues.

If you pull the other head, I’ll bet you find the gasket looking like charcoal
in the adjacent cylinder area….this isn’t uncommon with these, you probably got more hours than most

while you’re in there, might want to pull the lifters and check the condition of
the rollers

Shotgunn,

One word.... Cometic.

Thanks. Brad.

Ok sheese, We may need to start a go fund me for my back surgery. I will pull the other head Saturday. Thank you guys for your inputs and convincing me to do the right thing. Hopefully I'll be relaxing(recovering) on the sunpad in Party Cove next weekend. The charcoal thing was pretty convincing lol.

Glad I did the other side! Thanks