Temp sender bad?

[bobhol]

After the advice given to me from the members my temp gauge will pin when PROPERLY grounded(which I didn,t do at first),so my gauge seems OK. It reads 15-20 degrees high compared to my IR heat gun. Should I now assume the sender is bad and replace it or is there something else I am missing.....thermostat and impellar are new...thanks,Bob

 

[CheeseCutter]

Re: Temp sender bad?

Keep in mind that just because the gauge pegs, doesn't mean that it is accurate. You'd have to hookup a variable resistor to test for its accuracy.

You can test the sender to see if it's reasonably accurate. The service manual for my 4.3 gives expected ohm readings at various temperatures. But these are just ranges, so it could vary on a new one as well. For mine, the s/m gives a range of 121-147 oms at 140 degrees. That's quite a range -- sounds like merc doesn't expect the sender to be all that precise.

My setup is off by about 12 degress (verified with the IR gun). I live with it and just make my own mental adjustment to the gauge. Just some extra food for thought.

 

[bobhol]

Re: Temp sender bad?

Thanks for the response...now that I know the gauge is reading high I feel much better, but I am one of these guys that would like it correct if it reasonably easy to do ....a sensor is 40 bucks in Canada and if I knew that would fix it I would do it ...I just would like a test procedure to verify my suspicions...you make a good point about the gauge accuracy...thanks ,Bob

 

[BAproject]

Re: Temp sender bad?

Since you have the IR temp gauge and you know the actual temp of the engine it is not crucial to have it correct on the boat's gauge (really a matter of preference.)

What you have be careful of is watching changes in the gauge.....I am having similar prob's with my boat, and it reads 10 degrees hotter then the hand held gauge but keeps climbing up...so for me that's a problem....

Just my 2 cents

-BAproject