Indmar 400 Thermostat

[Mxmark4]

Dont forget to check your hester recirculation pump. Known leak location

[HFarr]

Yeah. I totally forgot about the circulation pump. Even though it always showed at the minimum mark, I ended up putting about 2 drinking water bottles in the reservoir, and the temp started acting better. So yep, probably air in the system from a slow leak somewhere. I will also try disconnecting the batteries for about an hour next time I am there. Maybe that will cure my display gremlins. My batteries are 5 years old now but seem to start just fine. However, I'm not sure if they may be part of the problem though. Even though the alternator is putting out 14 volts fine, I know today's electronics are battery dependant. Found that out with my daughter's brand new Kia that would shut off and not crank back for no apparent reason within 1 year. Dealership couldn't find anything wrong. Off of some internet chat room advice, I replaced what tested as a good battery and problem solved.

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[MJHSupra]

Slow leaks are hard to find. It took the dealer a little while to find mine after it overheated once.

[Mxmark4]

You can rent a pressure tester from Advance or Autozone and pressure test the system if you dont have one. They have a big kit that fits most reservoir caps.

[996scott]

The heater circulating pump was the problem for me. I was overheating if I was just ideling but as soon as I got up to speed the temp came back down. I removed the heater pump and saw that it had been leaking. I replaced the pump and decided to refill the system and it solved the problem.

https://www.indmardealersupport.com/news-letter.php

[HFarr]

Thanks! Both of these are sending me to check that for sure! I didn't think about the pressure test gage. Think I will start there!

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[jcarter20]

Do you happen to have the part number for the thermostat you bought? Mine got to 215 today and threw a code “ETC higher than expected stage 1”. I was only running about 31 mph for 5 minutes or so. Was going to start with a thermostat. It appears I do not have a sea strainer as it says it was optional on my model. All I see is a valve at the floor unless I am missing something. The temp did come right back down after I backed off and the code and check engine light disappeared after I turned the battery switch off and back on.


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[Holdmybeer]

It's the same 160* thermostat for a 6.2 ford 150 raptor truck. There is not a marine version.

Also, check your idler pulley. Mine locked up and the belt ate it until my boat over heated. Yours could be on its way out.

[jcarter20]

Got it. Thanks. I think I saw your post on the idler pulley and replaced 2 of 3 wheels last year. I did not realize there was a 3rd until I got into it. I wanted the job done, so I took a chance on the 3rd. May have to check now.


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[Holdmybeer]

You figure you run these engines at 3200rpm or higher for hours at a time. In the truck, at cruise speed, the transmission would drop to overdrive and the rpms go to 1800. The bearings in those pulleys wear out a little faster.

I was mad writing that post because I couldn't believe they were plastic.