Can't get any heat in engine......Help.

[alwhite00]

97 5.7EFI / BIII - Took the boat out the first time this season (don't ask) and I am watching the temp gauge - It never moved. I stopped the boat and felt everything and it seemed normal, Not hot so I figured the t-stat was stuck open. I pulled it out today and it was closed so I figured I would test it in boiling water - Opened and closed as it should, Anyone have any ideas? The gauge seems to be working as when I stopped it started moving but as soon as it was started it pegged left.

 

[SCORPIO]

Could your temp sender be bad? Take an ohm meter and with the lead removed from sender, check resistance. Do this with a cold engine. Reading should be around 400-500 ohms. Ground the lead and see what your gage reads, it should peg to hot. This will test both sender and gage as well as showing that the wire is intact.
Use an IR gun and see what the temp is on the engine with it warmed up. Also see what the temp is right on the sender.
Post your results.

 

[alwhite00]

Thanks, I'll give it a shot.

 

[SCORPIO]

BTW you read the resistance from the terminal on the sender to a good engine ground, a bare bolt etc.

 

[alwhite00]

I grounded the gauge and it pegged hot. I pulled the sender out and checked it and it shower 700 ohms. Is it possible that the t-stat housing is not grounded? I am going to put it back together and see.

 

[CliffA]

I grounded the gauge and it pegged hot. I pulled the sender out and checked it and it shower 700 ohms. Is it possible that the t-stat housing is not grounded? I am going to put it back together and see.

if the metal gromet in the t'stat gasket is not making good contact between the t'stat housing and the engine you can get errant temp readings on the dash gauge....this grommet grounds the t'stat housing....

cliff

 

[alwhite00]

I cleaned everything and now work in as it should, thanks.