2nd Gen Non-Engine/Transmission Help please: Engine temp gauge not moving

[JGK]

This weekend my temp gauge stopped moving. When I start up, it come up to the lowest mark (140*) and stays there. I haven't had a chance to pull up a long hill or some such to get the temps higher than typical to see what happens, but will try to do that soon.



The question is, should I be looking at a stuck thermostat or a bad gauge sender? Easiest way to tell which?



TIA,

-Jay

 

[Dieselnerd]

There is a rubber ring on the thermostat that gets sucked about half off and the thermostat doesn't close off the flow, coolant gets around it. When mine did that it wouldn't warm up past about 140. If your guage reads nothing when you first start the motor and gradually goes up to 140, my guess is the thermostat. If it goes to 140 right away, it's the sender or gauge. You can can also stick a thermometer in your radiator after you've run it awhile to read the temp but be careful opening the hot radiator. Thermostat is easy to change, just drain the radiator down a ways and unbolt the thermostat. Easy job.

 

[95REDRAM]

Sounds like Dieselnerd has it figured out. Another easy check (works on 95 12V at least) is to pull the wire off of the temperature sending unit and touch it to ground. Have someone watch the temp gauge while you do that. If the needle pegs out then the gauge is working properly. If the needle doesn't move then you have a gauge problem. I don't think that's your problem but wanted to pass along the info just in case.

 

[drawson]

Jay, I have had three stat do exactly what you'res is doing. This last time I installed a old gasser stat and it does cycle like the very first one did but there is no rubber to come off and get stuck.

 

[illflem]

Stock tstat cycled too much, new "improved" Cummins one didn't but ran too cold. $7. 95 190° Stant brand from Napa worked the best for me.

 

[JGK]

Thanks, guys. Yesterday, after doing some errands on the way home from work, the gauge started showing some heat. But it only moved between the 140* mark and the next one (about 165*?). So when I got home I left it running and ran in and got the infrared remote temperature gun (great "toy", Bill) and pointed it at the thermostat housing. It read 155*. So I'm thinking that's my problem.



At your suggestion, Bill, I will hit NAPA on the way home tonight and see what they have in stock. Don't happen to have a PN do you?



Thanks again,

-Jay



PS. Hope to see you in a week and a half, Dee.

 

[drawson]

Cool Jay, I was hoping you where still coming down after your own dyno days in Boise.

 

[JGK]

Got the thermostat from NAPA today and just got through replacing the stock one. Sure enought, some sort of wide rubber band like seal was sucked half-way through the valve. Otherwise, it looked fine.



The new one fluctuates more. A 'round the town test drive had it moving constantly between about 170* and 185*. The old one would stay pretty steady except at stop lights with the A/C on or under hard load.



May still get a new stock one (or at least a new seal), but it's fixed for now.



Thanks again,

-Jay



(Dee: while we had a dyno available, it just was too many $ and took too long for what you got. I'll wait for the event down your way. Other than that, and a little rain, it was a good, if small, event. Local dealership was encouraging and wants to do it again, so I hear. )

 

[BillBaker]

Have you experienced this firsthand?...temp gauge jumping to 140 and staying there. I have another thread where I did a coolant flush and changed out the thermostat with a Gates 180 degree from Geno's. My temp gauge was fine before I did these now all of the sudden my temp gauge does just that...jumps to 140 and doesn't move.