T-stats keep sticking open or closed

[LAC_STS]

I have replaced the T-stat in my 5.7 3 times in the last 2 months. I have the kind of T-Stat that uses the rubber ring to secure it to the top of the T-Stat housing.

The first time I noticed that the engine was running cool. It would only get up to about 120F unless I really ran it 3/4 throttle or more. Then I went to the boat again and when I started it it heated up to 140 then 160 then 180 then I shut it off.

Took the T-Stat out and replaced it and all was fine again. Engine would warm up normally and stay at 150 or so.

Then a few weeks later, same thing. First I notice that the engine is running cool then it got too hot the next time I started it.


Yesterday I went out on the boat and it was running cool again. So I think the T-stat is stuck open again.


Whats up with this? Ive replaced the T-Stat according to the manual. I use a new rubber ring and new T-Stat housing gasket every time.

 

[ziggy]

Re: T-stats keep sticking open or closed

have ya tried cooking (in a pan of water) the offending tstats w/a thermometer present in the water to determine if the tstat is the issue...

a tstat should start to open at whatever is stamped on the tstat (143*) in my case. then be full open at + 20* (164* in my case). when cooling, it should be closed again by whatever is stamped on the tstat..