Hi all
Trying to diagnose my system. Just bought the truck, a 92 Pickup 22RE, and noticed the temp needle moving slightly from 0 but not much. Figured it was the tstat stuck open. Took it apart and found that the tstat was modified always open by PO so I installed the painfully expensive OEM dual stage one. Unfortunately, the gauge still doesn't go to the middle. On highway trips it will sometimes get to 1/4 but most of the time it will be at the 1/8th mark or lower.

I grounded the temp sending wire and the gauge immediately pegged to max so I'm assuming that works fine
I tried turning the heat on to see how hot it was and was not feeling much heat at all. With the tstat replaced, what else would cause the coolant not to get hot enough?

Edit: Checked the heat cable/rod to the valve, moving fine

 

The temp gauge observations are normal, for these trucks anyways. That's just how they are. But watch...someone will argue with me on that...whatever...

As far as the heater not working very well, you need to burp the air out of the system.

In other words...you have no overcooling problem.

Just curious. What did the PO do to the t-stat? I'm having a real hard time trying to imagine that one.

 

The only thing that would bother me is the little amount of heat from the heater. But that could be as easy as a cable came off on the heater system somewhere *valve on firewal, or flaps in the truck*

 

They cut out the center piece of the tstat leaving an open hole. Picture attahed


Ya. Might be air. I jacked up the front end and ran it with the rad cap off though

 

If the fan clutch was bad and the fan was always working at max, could this cause the issue?

 

Since I don`t have one of that year I can`t say the gauge reading is normal.

It could be a corroded connection at the sending unit or the sending unit itself wearing out.

 

I have the same problem with my 94 22re. During normal driving, summer or winter, the needle sites at 1/8 the way up. I've changed the tstat, sending unit, fan clutch, and checked my connectivity and ecu response of that port and all seem in working order. It sometimes scares me though since when the needle does get up to 3/5 or more occasionally sitting at a light, I wonder if it IS really much hotter since it went up relatively alot!

 

How do you test the one prong sending unit for accuracy? I see in the manual how to test the temperature sensor for the computer but not the sending unit to the gauge

 

There's a procedure for testing the gauge. http://personal.utulsa.edu/~nathan-b.../6combinat.pdf There isn't a published procedure for testing the sensor, but this isn't NIST-traceable accuracy, anyway.

The lack of heat is a concern, but before I spent too much time on this inherently not-too-accurate gauge, I'd start with the thermostat (you've done that) and the heater controls (the heater valve is mounted on the firewall, so have someone move the temp control and watch the valve work from under the hood).