Engine overheated, really frustrated.

[crr1876]

So yesterday afternoon I took out my "new to me" 07 LSV for only the 3rd time. The first 2 were back in October and since then I winterized thanks to forum instructions, dewinterized last week including installed new johnson 812b impeller. I made sure all my hoses, plugs were tight and everything was in good shape. On the 3 trips I have been on the boat seems to run about 180 degrees F at baseline. So yesterday I ran around the lake for 2 hours, monitoring all vitals with good oil pressure, temp about 180 consistent and good voltage. I had no water in bilge and boat was performing very nicely, quick, responsive, just like on the test drive. After 2 hours I decided to have my wife drive with perfect pass while I wakeboard behind the boat for the first time! I maybe took 4 or 5 quick pulls for a total of 15-20 minutes. My last words before I jumped in was to monitor temp gauge, it should stay around 180F but its my fault for not reminding her or asking for the temp between pulls. After I got back in the boat i was pretty chilled from the 60 degree water and my wife wanted to drive back to the dock. She began to throttle but didn't notice the same power. I immediately saw temp gauge and it was pegged hot, past 240. I immediately shut her down, opened engine compartment and sat for at least 20-30 mins. At this time it was getting dark, nobody else was really on the water so I decided to limp back to the dock maybe a 10 minute boat ride. During this time the boat seemed to run ok but with less power and also make a small squealing noise but the compartment was open as well.

So far I have checked

1. new impeller, which appears fine, water came out of pump when i took off the cover, all spines intact and in good shape
2. pulled out thermostat which appears old and cruddy looking, however when boiled/cooled it does open/close. My plan is to replace it anyway since I'm there and it looks cruddy. (maybe its not opening all the way?).
3. checked raw water intake strainer which appears ok, not plugged up.

This AM when I turned key to AUX position temp gauges went back to far left, less than 100F.

How can I tell if the water pump is functioning properly?

Also, I am obviously pretty worried and frustrated that there might be bigger mechanical damage from the overheat. I believe I read in another thread that mmandley had mentioned the boat will go into "limp mode" to protect itself when it overheats which is maybe what that loss of power was? I was thinking I should just change the oil to be safe and look for metallic particles or burnt smell?

I am honestly pretty frustrated this happened on only my 3rd trip with the boat, and first time with a rider. Any advice or tips would be really appreciated. I felt like I really did my homework and research to prepare to properly operate the boat but maybe I just have bad luck. I also thought about reaching out to the dealer I bought it from this past October, however my thoughts are the response would be I bought a used boat, as is, which ran fine during the test drive.

Should I be ok to start at the house with fake a lake and just keep a close eye on temp since any damage is already done or should I prophylactically change the oil before I start the boat again, just to be safe?

Many thanks for the help.

[lee]

Do the exhaust hoses look burnt and brittle? You could try and run it on a fake-a-lake to see what will happen. If you do not get water coming out of the exhaust in around one to two minutes cut it off.

[crr1876]

No hoses or anything look burnt, also I had no smoke at all when I opened the engine compartment (Idk if that makes any difference?)

[lee]

Did it feel hot or warm or do you have a sending unit going out?

[crr1876]

So I was able to touch the exhaust with my hand without burning or anything (didn't feel too hot), thought about maybe the sending unit going out however there was definitely a perceived loss of power or "limp mode"?. By sending unit are you referring to the temp sensor in the top of the block near the thermostat? If that sending unit was going bad could it cause the boat to run with less power ("limp mode") to protect itself thinking it was overheated even though the running temp was actually ok?

Also I'm about 6'1" 185-190lbs, I don't think the added stress of towing me could have pushed the boat over the edge to overheat right? I would guess that 5.7L V8 could barely tell I was back there?

[parrothd]

Run in on a fake a lake and see if water comes out the exhaust or it over heats.

[mmandley]

I agree running it on fake a lake, you should get water pretty instantly but honestly from your post, nothing you do in the drive way is going to truly test it.

Sounds like it runs fine then randomly over heats.
Now this could be a bad thermostat randomly sticking.
It could be a water pump starting to fail.
It could be something completely different.

In your situation I would replace the thermostat.
Replace the water pump
You said you have a new impeller.

I wouldn't worry about oil, it has to be 300+ before is even starting to burn.

I'm not a fan of shotgun repairs but there is no good way to flow test your water pump.
Only other thing I can even think of, is if your exhaust risers are clogging.

I wouldn't dig into that.

Water pumps are easy to replace, not real expensive, good insurance on an older engine.

[crr1876]

Thanks guys, as I'm kind of a newb where is my best resource for buying a water pump? I'm assuming online, I guess there is no good way to actually test the water pump either?

[zabooda]

My water pump worked all the way to failure. It mechanically started to fail and make loud noises before the pulley broke off and dropped into the bilge. The water pump is an automotive part so it is cheap.

[lee]

http://marineenginedepot.com/MP/Mari....3L5.0L-5.7L)/