Temp gauge not correct,I think

[bobhol]

First..3.0 mercruiser,alpha one gen 2,new impeller,new thermostat.My gauge seems to run from 180 -185 all the time which I feel is on the hot side .I bought an IR temp gun and readings at the base of the thermo housing just in front of the tappet cover at the gasket reads 167.The side of the block is 170 and all hoses are below that . I grounded my sensor wire to ground and my gauge went to 190 immediately but not to 240 .Is my gauge bad ?....Thanks,Bob

 

[Silvertip]

Re: Temp gauge not correct,I think

Not necessarily. Measure the voltage on the +12 V (the "I") terminal on the gauge. Make sure you measure to a "good" grouind. If less than 12.6 volts check for corroded connections. If that checks ok, then verify the ground connections. High resistance in either lead will cause an erroneous gauge reading.

 

[Don S]

Re: Temp gauge not correct,I think

I grounded my sensor wire to ground and my gauge went to 190 immediately but not to 240 .Is my gauge bad ?

Could be a bad gauge. It should have pegged the gauge when the wire was grounded.
Before you blame the gauge, do the same test at the gauge. You could have a problem with the sender wire between the gauge and the sender.

 

[bobhol]

Re: Temp gauge not correct,I think

Thanks for the quick response .I will check that out this wknd. The "good" ground comment was interesting as I did ground it against a clamp end.If I find the gauge is not the problem ,could it be the sensor and how do I test it or should I just replace it...again thanks...bob

 

[bobhol]

Re: Temp gauge not correct,I think

Thanks Don ...I will follow all advice...I am relieved it is not running too hot but now have to get the gauge reading right....Bob