Overheat! Advice appreciated - Maxum Boat Owners Club

Phrogboy · 05-09-2015, 05:02 AM

Fellow Maxum owners,

My pride and my "I need to use my new boat this weekenditis" could get the best of me, therefore I am turning to you guys.

I finally got my boat on the water today. I had just purchased it last October and had a few trips out before winterizing it. Since it has been only 5-6 months since it had been tuned and overhauled, I really did not put a lot of effort into spring maintenance. She started right up and purred at idle for a good 20 minutes before I took her out. Unfortunately I went out at low tide, and soon found myself in two feet of water and muck... in the channel. I raised the engine, but then the alarm went off. I scanned the guages, and nothing stood out right away. I turned around and headed back, with the alarm going off. Engine temp then started to rise, and by the time I made it back to dock I was up around 200 degrees.

I let her cool, and let the tide come in a bit while working on a few other things then started her back up. She purred again and held 140 for at least 15 minutes as some relatively clean bay water flowed through her.

So, shall I continue with the weekend after letting some clean water run through her? I will probably put the ears on her even though she is in the water and try to clean her out some more. I do think it was the silt, but in my previous boats (Sea Ray 5.0), I never had an issue with an overtemp that quickly into a low draft in silt situation.

It's a 5.7 EFI Bravo III.

Thanks for any advice.
Phrogboy

mmwjr · 05-09-2015, 05:12 AM

When you raised the drive how high did you raise if? Could you have raised it to far that the raw water pick up was sucking air?

Phrogboy · 05-09-2015, 05:15 AM

It was 3/4 up. The pickup was still in the water, but it was pretty stirred up.

mmwjr · 05-09-2015, 05:18 AM

I guess my next question is how old is the impeller?

You can attempt to go out but if the temp starts to rise turn around.

BTY do not run the engine at high temps for long otherwise you cook the engine and be faced with replacing it.

Phrogboy · 05-09-2015, 05:32 AM

Solid advice for sure. The impeller was replaced just before I purchased it, so practically brand new. I will be watching it for sure.

What is considered high temps. I was up to 200 today, but the guage goes to 240 with no "red" line. When should I be concerned that damage has been done?
Scott

itsabowtime2 · 05-10-2015, 04:12 PM

Although the impeller was new, running at hot temps does lower the life of it.

As far as operating temps. Closed cooling about 175-ish. Raw water about 160-ish. 200is hot. Remember, water boils at 212.

mmwjr · 05-10-2015, 04:52 PM

Quote:

Originally Posted by itsabowtime2

Although the impeller was new, running at hot temps does lower the life of it.

As far as operating temps. Closed cooling about 175-ish. Raw water about 160-ish. 200is hot. Remember, water boils at 212.

+1

At 200 you risk damage to the engine. Just because the impeller is good there are other things such as bad exhaust that can cause it it overheat.

Kevlar7r · 05-10-2015, 06:11 PM

Also, with a raw engine, you do not have a pressurized cooling system, therefore it will boil at 212. In a car with a pressurized system, you can often get up to 220-240 without boiling. Lots of bad things happen if the water boils.

Its possible you just had some muck, and it flushed out. I might pull and check the thermostat. Lots of potential for stuff to collect there, and also, it may have gotten stuck over the winter.