Really odd problem with t-stat/cooling system

[danfinn]

Re: Really odd problem with t-stat/cooling system

First thing to check is make sure you didn't put the t/stat in backwards, a common mistake. Next, you may have to check the impeller.

Thanks. First thing you may want to do before posting in a thread is to read all of it. Already done everything you suggested.

 

[TiredoleBoy]

Re: Really odd problem with t-stat/cooling system

Ok so after seeing the diagram outlined in manuals. You have the closed system, Correct?. Ok so all of the sea water issues have been covered.
Now have you tested the coolant cap? Also do we know if the circulating pump is weak or not operating as expected? Can you see antifreeze circulating? There could also be a clogged passageway and the motor may need a back flush. You should be able to remove the cap and run this engine without antifreeze pissing out. Once the therm opens you should be able to see the anti freeze circulating. I mean this cannot be much different than a car engine in terms of coolant passages. ( of course without the sea water).

 

[Philster]

Re: Really odd problem with t-stat/cooling system

Buying used often means:

Replacing every fluid and filter.
Replacing pump/housing/kit/impeller
Replacing manis/risers/elbows (or removing and inspecting them and replacing gaskets)

Then it means performance checks, if they were not done at pre-purchase.

WOT and RPM top speed should be noted.

Engine temp (the cold, the warm and the hot).

Cold: MUST have a t-stat to warm up and remain at op temp -- usually 160 plus.

Warm: Must remain warm when using... usually 160 to 175, or just a hair more

Hot:. If she gets hot, you need to inspect the entire cooling system. Hoses comg in from drive can narrow as corrosion crushes them down. Now, by removing a t-stat these narrowed hoses can be offset (believe it or not). It has to do with how fast/hard the sucking is with the t-stat out (usually lower,). This can help keep the incoming water, which is running thru narrow tube(s), from getting vaporized (which reduces cooling capacity). With the t-stat in, the sucking is more even/strong, and incoming water can vaporize, creating bubbles. Eventually, even having the t-stat out won't help.

Make sure the incoming water is bubble free. Do that with the t-stat in! Otherwise, test might not be valid.

Running w/out a t-stat = big engine wear. Metals aren't matching up, and fuel/air ratios aren't great for long-term health of engine. Very bad news.