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Temp not registering on temp gauge

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Bruce Enke

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"I have a 1995 5L Mercruiser t

"I have a 1995 5L Mercruiser that I bought used. It hasn't registered a temp on the temp gauge since I've had it. I've tried grounding the tan wire that goes to the gauge from the sending unit, and the needle pegs so I'm assuming the gauge is working. I just replaced the sending unit but that didn't change anything. Any suggestions on what might be wrong or what else I could try? Thanks in advance for your help."
 
did you wrap the sender with t

did you wrap the sender with teflon tape? or any sealant that would have insulated the threads? the threads complete the circuit to ground. and random tip: do not test a sender with a lighter..it wrecks it...
 
"Just what I was thinking Hy s

"Just what I was thinking Hy stat.
thumbs_up.gif
or sender is bad.
Kurt"
 
"Hmm...the new part came with

"Hmm...the new part came with a red sealer on it. I didn't clean that off, do you think that could be it? That the original sender was bad and the new one I put on is insulated?"
 
"No, that red stuff is cunduct

"No, that red stuff is cunductive and note they didn't put but a little on one side. I say sender inop.
Kurt"
 
"As a side note, did you inspe

"As a side note, did you inspect the bore for the sender? is it clean and is the sender actually seeing water?
kurt"
 
So you think the new sender I

So you think the new sender I just bought and put on yesterday is bad?
 
Is there a way to check it oth

Is there a way to check it other than using hot water? Or buying another sending unit?
 
"If you have a voltohmeter you

"If you have a voltohmeter you can check the resistance across the sender.
I beleive that it varies between 220 ohms at room temperture to 40 or less at 250 F.

To test the high temp sit it in boiling water for a minute or two then take it out and quickly test it. Water boils at 212, so you should get a reading of perhaps 70 or 80 ohms.

If you get readings in these ranges the sender is Ok.

Rod"
 
"Thanks all, I will try these

"Thanks all, I will try these things and see what happens."
 
"check resistance between the

"check resistance between the sender and a good grond,if you have resistance replace the gasket below the thermostat housing with the proper one."
 
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