Engine overheated, really frustrated.

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.

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.

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?)

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

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?

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

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.

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?

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.

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

Your brand new impeller may be defective even though it looks normal. The squealing noise may be the giveaway. Check it using the test in the first post in this thread:

https://forum.moomba.com/showthread....the-week-month

I checked the impeller and didn't notice it free spinning when holding pliers inside the channel.

I believe this is the water pump I need, just to confirm

https://www.bakesonline.com/detail.aspx?ID=774

Also, how worried should I be about having caused significant mechanical damage? I'm getting a general feeling that I shouldn't worry too much about it, just change thermostat and water pump then go ahead and test and check for overheating. I was considering doing a compression test on all cylinders and changing oil before I start again, but it really doesn't seem necessary from the replies?

On a side note should I buy the OEM 40 dollar thermostat or go cheap and get the sierra replacement?

Thermostats are cheap, no need to spend 40 .

Compression test is the best way to check for blown head gasket, also water in oil.

The only other thing to possible check is the belt. If the belt is loose it may be slipping on the water pump and therefor not spinning it. That will make a squealing noise as well.

So like I said I'm a newb but I learned today that I have two water pumps, the Johnson raw water pump and the main circ pump that was linked earlier in this thread. I have a new thermostat and main circ pump on order and plan to do a compression test. I will keep you posted.

Thanks for everyone's help thus far, this forum is a great resource.

If you happen to have another impeller kicking around you may want to try comparing the two.. You may find this one is longer, or deeper than the other. I found one like this , and it caused a squeeling noise from basically rubbing on the front cover withe the brass screws..Not sure what caused this in mine as it was a impeller i had used the previous season and packed in Vaseline... As per Moomba instructions.. I do not do that anymore.. Maybe this will help.

Wasn't there and issue with hoses on the 07 models that would fail overtime. I remember the person I sold my XLV to in 2010 having an issue after a few weeks after I sold it to him.
Might check the hoses underload and see if they are collapsing.

Start with some basics. Did you check the oil for signs of water. The caps may have a milky coating on them. That would be a key sign for head gasket during an over heat. Pull the temp sending unit and check it with a volt meter to see if it has failed. Check online for the resistance for your model. A failed sensor send a signal to the ECM and yes it will/can go into limp mode.

Both of those things are basically free (if you have the tools). Compression test if you have or can "rent" the tool. Then put it on a fake a lake and see what happens. After that, think about replacing parts and spending money.

Could you explain in a little more detail how to check the temp sending unit with a voltmeter?

Just an update, ran a compression today this AM and all cylinders are within 123-132 which makes me feel a lot better! Also plugs looked good.

You want to measure the resistance (ohms or Ω). The sender has one wire, so you measure between that and a chassis ground point. The basic idea is that it should be high resistance when cold, something in the 1000's of ohms and lower resistance when hot. Normal operating temp might be somewhere around 500Ω.

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Originally Posted by crr1876

Just an update, ran a compression today this AM and all cylinders are within 123-132 which makes me feel a lot better! Also plugs looked good.

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Fortunately, there are lots of ways for the temp sender/gauge to go haywire, read like its overheating and put you into the limp-home mode which don't actually involve the engine overheating.

I had an impeller hub let go from the rubber and only he brass part was spinning. I cranked the boat over while watching it. You may have to have someone else crank it while you watch. My .02 worth

A good way to understand the severity of a "thermal event" is to check the inside of the 90 degree elbow on either of the manifolds.....if you were not pumping water for an extended period the inside will be burnt/melted. They get brittle after being so hot and will fail - as in pop right out of the manifold flooding the engine top down with water.
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Quote:

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Originally Posted by crr1876

Just an update, ran a compression today this AM and all cylinders are within 123-132 which makes me feel a lot better! Also plugs looked good.

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Seems pretty low, but consistent. I would maybe check for a leak down test. My compression is a good 180-190.

Yea I figured out I didn't do my compression test exactly right. I only removed 1 plug at a time instead of all 8 at once and I didn't have the throttle wide open, just up at 90 degrees. I don't necessarily think it's worth testing again since they were all very close to each other and above 100 but others might not agree.

Not all gauges are the same, they will give different readings. The important thing is that all cylinders are in the same psi range within 10%.

I think your over worrying, take the boat out and see what happens. If you overheated it too lockup, then you've got problems your not going to do more damage by running it..

Quote:

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Originally Posted by parrothd

Not all gauges are the same, they will give different readings. The important thing is that all cylinders are in the same psi range within 10%.

I think your over worrying, take the boat out and see what happens. If you overheated it too lockup, then you've got problems your not going to do more damage by running it..

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I definitely agree with you. I'm swapping in a new thermostat and water pump then I fully intend to go run the boat!

Just an update, I replaced both water pump and thermostat, got everything back together and ran the boat on the fake a lake. It ran great in the yard heating up to 180 then watched the temp gauge as the thermostat would open boat would cool to about 170 or so. I ran the boat over 30 mins with some good revs in neutral and it never once overheated.

Bad news is after I killed the motor (but had left perko switch on) as I was cleaning up tools etc, about 2 hours later I happened to glance at the temp gauge and it was pegged again over 240!!! I immediately turned the key to accessory position and the gauge went back to far Left instantly. This leads me to believe I actually never had a true overheating problem but actually have some kind of electrical or sensor type problem. This fits hat happened on the lake cus my wife had shut down the motor while I got back in the boat and put my gear away. Unfortunately I'm kind of lost as to what to do next, idk if I should just take it in and let the professionals take over?

I wouldn't fret none. It appears you have bleed through your temperature gauge from one battery to the other battery (floating ground) that clears itself with the 12 volts applied to gauge. The changes you see is probably from the RTD dropping resistance as the engine cools off and allows the current to increase (talking mA). It leads me to believe the Perko setup needs to examined but check the grounds as they need to be tied together.

I know it doesn't pertain to this thread but I have a 2006 moomba mobius lsv with the 325 indmar.. sometimes whne in am cruising 30+ mph I get a very loud squeel for a min and whne I let off it goes away.. and if you get back on it it runs fine.. only does it sometimes? boat has 700 hrs on it

A serpentine belt