Engine trouble on the 4th weekend!

[Jetdriver]

Hey guys! Hope everyone had an awesome 4th weekend!
I had a problem with my boat on friday(of course it happened at the start of the weekend) and I'm seeking
some advice or insight into my problem.

I took the boat out and towed 3 surfers then shutdown the engine and floated for about 20 minutes. The wind picked up so we decided to head back to camp. We were on plane for about 2 minutes at 36-3700 RPMS and out of no where the power starts rolling back on me and I see that the small digital display is saying overtemp 205 or something like that. It was running normally while surfing and I hadn't noticed that the temp was climbing. The engine had sounded totally normal up to the point it shutdown on its own. I popped the engine cover and it was definitely running hot. We hung out for about 30 minutes and had a couple barley pops waiting for it to cool down. When the temp indicated about 160 I attempted to restart it. The engine made an awful clunk sound and wouldn't turn over. I decided to call my friend and get towed in.
I left the boat at the dock for a good three hours and attempted to drink every beer in my cooler to make the pain stop!
After chatting with a buddy about the problem for a few I went down to the dock and checked my impeller(new this season and looked perfect), checked the thermostat, removed and cleaned my raw water strainer. The strainer did have some gunk in it and it is a relatively new component in my boat so it's a suspect in the overheat problem.
I attempted another restart with the same locked up condition. I pulled the boat out of the water and noticed more water than normal drain out of the FAE. (I've been running the FAE for almost two seasons without any issues)
I suspected it was hydrolocked although I have no clue how it happened. I removed the spark plugs to verify and voila, there was quite a bit of water in multiple cylinders. I pulled the fuel pump power and ran the starter to expel the water. I squirted a bunch of WD-40 into the cylinders and ran the starter again. Did that twice for about 15 seconds each time.

My questions are these-

-How did it get hydrolocked? I know water isn't going into the exhaust with the engine running at that speed. I've heard you can ingest water through the top end with a bad head gasket. Boat has 320 hours on it so I'm wondering if that's very likely. Maybe when the engine shutdown it dieseled a little and sucked some water up?

-Why did it overheat? I'm leaning towards the gunk in the strainer but I'm not positive. I'm planning on replacing the impeller to eliminate that variable.

-What kinda possible damage am I looking at?

Thanks in advance guys!

[Jetdriver]

This is what was in my strainer before cleaning it.

IMG_0258.jpg

[Wakeman22]

That is some buildup in there. I would lean towards that as the culprit for over heating. But I would not rule out the impeller either. Did you get in in the correct way and make sure it is not spinning on the shaft. If the engine dieseled as it shut down then there is that possibility that it sucked up the water. Do you have the butterflies in the FAE?

[Jetdriver]

No butterflies on the FAE, I think I'm going to email Larry at FAE about this and see if they can send me a set to retrofit mine with. I'm unsure this is how it became hydrolocked but it is possible. From now on I will be cleaning the raw water screen each outing.
Thanks for the reply Wakeman

[chpthril]

It ran hot and you had water in some cylinders. Hate to say it but 2 + 2 typically = blown engine. The water most likely is a result of warped head(s). Given that is was over heated, the water in the cylinders is likely not accidental or a coincident. The two are directly related. If the engine was starved of water, the water level drops as the circ pump continues to pump water through and out. This makes the temp sensors inaccurate and the internal engine temp much hotter then indicated.

Hope im wrong though. Good luck.

[Jetdriver]

Thanks for the insight Chpthril, I'm really hoping it's not blown! At this point I think I'll do what I can to address the possible causes of the overheat and hook it to the hose and see how it runs. Fingers crossed!

[dj2]

I would pull the engine and do a full inspection.... unfortunately there is such thing as more damaged if you try and run it again. Right now you may have some bent rods and a damaged crank, trying to run it could easily result in a hole in the block and leave you with replacement of the entire engine rather than a rebuild and some machine work.

[UNSTUCK]

Bend rods,crank, push rods, etc can easily be found without engine removal and just turning the engine over by hand. I'd do these tests first to find any issues. If they pass, run it!

[dj2]

It's not my money to spend but I have pulled plenty of engines in my time on the verge of catastrophic failure that weren't detected until the oil pan was pulled. Make the decision that best fits your budget.

[Jetdriver]

Assuming that the water was ingested after the engine shutdown(or in the process of) is the starter strong enough to bend con rods, crank, etc...during attempts to restart?
Also regarding turning it over by hand, should I be doing that without taking anything apart and going by feel and sound or should I remove some things first to get an eye on some internals.
Thanks for your advice DJ2 and UNSTUCK!

[Thegerman618]

how many hours you have on the motor Jet?

I believe you have the MP 5.7 340HP?

Compression on that motor should be about 206-210 IIRC. Sorry to hear about your motor, I hope its not as catastrophic as it seems. Good news is sounds like there are a bunch of guys that have done the work before.

Keep us posted!!

[Jetdriver]

It's the Marine Power 5.7 340 HP. 320 hrs on the motor. It wasn't but a month ago that I installed the raw water strainer and I'm leaning towards it partially clogging as the cause of my overheat. Shoulda been cleaning it after each use. The last time I checked it it didn't appear dirty. Sucks when you go through the effort to add something to better care for your system and end up jacking it up! Kinda my luck as of late. Still had an awesome 4th though
When I cycled the starter to remove the water from the cylinders it didn't sound bad. Obviously with the plugs out it sounds a lot different but it didn't seem to be grinding, catching or binding on anything.
I'll definitely let you guys know what I figure out.

[freeheel4life]

How does the oil look?? Milkshake?? Also, verify which raw water pump you have. Believe some marine power engines had a jabsco RWP and some have a Johnson.

[dj2]

I would do a couple things minimum before trying to start it: do a compression test as you could have damaged rings/ring lands or a bent connecting rod, if you have any cylinders that are more than 10% lower than the rest, you likely have a problem. Next do a leak down test, you can get both of these testers on loan from your local parts store. Just need an air compressor to do the leak down test. Finally If you have a dial caliper you can use the depth rod to measure the stroke of each piston through the spark plug hole, just be sure to measure each one consistently. If all these tests come back good then I would feel more comfortable firing the engine.
Again, this is my personal opinion and I prefer to take a few hours checking this out rather than risk replacing the engine.

[Jetdriver]

Freeheel, pretty sure the last impeller I put in was a Johnson but can't say for sure off the top if my head, I'll double check. The oil looks fine, was changed at the end of last season and still looks new. No sign of water.

DJ2, I definitely don't want to grenade the engine rushing to get it back on the water. I've rebuilt plenty of motorcycle engines and transmissions so I'm not a total newbie to internal mechanics but I've never tackeled a car or boat. I will go to O'Reily and rent what I need to accomplish those tests. Can anyone tell me specifically what I should be looking, listening, feeling for when turning it over by hand? I know the obvious grinding, binding, etc... anything else, more specific the better!

Thanks for your help guys