I have a buddy that ran his boat into the sand. We had to replace both water pumps, back flushed everything, cleaned out his sea strainers. We also pulled out the block drains but there was nothing that came out of them. I pulled the large hose that goes from the T-stat houseing to the circulator pump and that was clean with no sand. I pulled off all the hoses to the manifolds and risers and they were all clear. The motors were still overheating. I pulled out the T-stats and then tried and the motors run at 150 or cooler degrees all day long. So my questions:

1) Will the motors build temp with out T-stats normally or do we still have a blockage some place?

2) Will running the motors with out T-stats be bad as long as he warms them up slowly since they are getting to the 150 anyhow. The reason we want to do this is his T-stat houseings are rusty and those bypass openings are quite clogged. This way he can run his boat until he can get the new stuff.

The motors are 420 454's.

Thanks for any help.
Jon

I think you've still got some issues as every boat I've had that we ran with thermostats removed would not build temp.

Could it be possible that the thermostat housing is so corroded that it's causing a restriction?

....If you clowns have been in my tool box, you better put everything back in it's place!!!

not a big problem as long you give time for the oil to warm up a bit before WOT ! I'd put t-stat back on when you have them, simple as that!

I run my twin 454s without t-stats and it runs great. If you do, they should have some constant flow thru holes drilled in the t-stat otherwise you will get major temp changes when the t-stat opens and closes. Thats not good for obvious reasons. You would get big steam ejections from the exhaust when the t-stat opens. Terrible shock to the engine.

Running without Tstats is not good, no matter what any one tells you. Temperature is needed to bring the engine tolerances up to spec, also without Tstats you will not burn off the moisture. On the Donzi site there are a few posts with pictures of the Goo that builds up and pictures of glazed cylinder walls from cold stuck rings. A 160 is the minimum stat for a boat engine, I am F/W cooled and run a 180. Anyone not running one pull your oil fill cap and tell me your valve covers are not showing moisture build up, another thing I have seen is the valve springs rust. Once rust starts on a valve spring it will break in short order. Even the guys on the Donzi site with blower motors are running Tstats!

I agree with Biggus, have been down this road before, you are not going to run 150 degrees with no T stat. something eles is going on. Check out my thread on Serious Offshore 38 Top Gun cooling problems

I ran my boat without t-stats and would not get hot enough to clean the moisture out from the oil....installed a bypass on my crossover setup and a t-stat nows runs consistant 140-150...Rob

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Mine run 140 without t-stats. At least thats what the gauge says.

Maybe I need to check that out and verify.

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