Temp guage not working (I think)

3ball

Seaman
Joined
Feb 28, 2010
Messages
50
Temp gauge on my 2002 Reinell is not registering. I don't think its a problem with the gauge itself because when I turn the key the needle moves. It goes to about 100 deg then just stays there. (Its not possible that that is the actual engine temp is it?) I think it may be a problem at the engine. What does the connection look like? & where should I look for it?
 

3ball

Seaman
Joined
Feb 28, 2010
Messages
50
Re: Temp guage not working (I think)

I have been researching this some more & will test the sending unit. can someone tell me where this and & what it looks like? engine is a Merc 5.7. Thank you
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Temp guage not working (I think)

It can be located most anywhere on the engine but typically in the thermostat housing or the crossover water passage in the intake manifold.
 

3ball

Seaman
Joined
Feb 28, 2010
Messages
50
Re: Temp guage not working (I think)

OK, I found the sender.
  • I grounded the tan wire to the block & it pegged the gauge.
  • I removed the sender put it in hot water then grounded it back to the block
When I did this I got a reading on the gauge. My next step is to test the thermostat. Am I correct in this assumption?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Temp guage not working (I think)

If the engine is not coming up to temperature someone in their infinite wisdom may have actually removed the thermostat thinking they were doing the engine a great service. Engineers put one in there for a reason -- it's called engine efficiency. So step 1 is to see if you actually have one and 2) if you do, test it, and if not 3) install a new one.
 

3ball

Seaman
Joined
Feb 28, 2010
Messages
50
Re: Temp guage not working (I think)

Figured it out. the thermostat was in there but it was seated wrong. going to re-installing it now to test it. I don't have a new gasket until morning though.
 

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NYBo

Admiral
Joined
Oct 23, 2008
Messages
7,107
Re: Temp guage not working (I think)

Hard to tell exactly what is going on from the pic, but it looks like the thermostat rim has corroded away to the point that it got pushed up into the housing. I would replace it.
 

3ball

Seaman
Joined
Feb 28, 2010
Messages
50
Re: Temp guage not working (I think)

Actually everything was pretty much OK. T-stat still worked (I will replace it anyway) It looks like when the last person put it in it slipped a little when they turned it upside down & it did not seat right.
 
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