So, I bought an '87 I6 with 98k on it. The truck runs great and has a small oil leak the problem I'm having now is that the temp sender is not working. I went to replace it with a Duralast with the same result. The guage comes up to the "C" and nothing more.
My questions is, I have read that Duralast senders don't work, is this true? Also, I heard the only ones most can get to work are the motorcraft senders, is this also true?

Just to reiterate I'm talking about the sender with one wire, not the sensor, with the two wire, and not the air temp sensors either. I read a few threads where somebody asks about a temp sender and somehow people have brought up that the air sensor has something to do with collant temps. I confirmed this is false; through the repair manual.

 

Ground out the sending unit wire to the engine block, does the gauge peg to full hot?

 

Forgot to mention ran the check, the gauge is good. Test has been run, when I grounded the wire with an alligator clip and turned it to the on position, the gauge went to the "H". Anybody hear anything about these cheap duralast senders not working?

 

Last night I was doing some research on this temp gauge issue and found some info that has led me to believe the Tstat might be stuck open. Number one because the gauge slightly rises and drops when I turn to the on and of position after a decent drive. Also last night I drove about ten miles and wnet to feel the intakemanifold which was very cool while the radiator hose was extremely hot. And another reason is that it takes a 15 minute drive to get the heater blowing some hot air...

Any help is greatly appreciated, thanks in advance.

 

Last night I checked the coolant level and its good. Also after a decent drive I checked the temp on the intake manifold and it was very cool, also my radiator hose was pretty dang hot.I have also noticed after some research the time it takes for the heater to blow warm air is greatly related to how long the engine takes to warm up... I have been noticing that it takes right around 10-15 minutes for the heater to blow hot air... Would the Tstat being in an open position cause these problems, including my non working temp gauge? Fyi I have already swapped the sender with a new one and ran the grounding test, gauge and wiring are fine.

 

replace your T-stat... they are only a couple bucks and you'll know that is eliminated. Your heater core could be blocked up too but wouldn't cause the guage problem... Be careful with the tstat housing. Don't over tighten (it can break easily at least the one on my 83 did...) and use a thin layer of high temp silicone on either side of the seal (sometimes these things have a bad time resealing to the head and not leaking). I have the same problem with thumper but haven't gotten around to driving/fixing her yet.

 

Yeah, I checked prices on that yesterday I'm getting a tstat right after work, I read that you have to empty the collant system lwhen you do this, is that necessary? Also how much coolant is held in the system? If iI'm gunna empty it I figure might as well flush and replace. Thx

 

If you have not ever changed your coolant now would be an excelent time to flush your system, and replace with all new coolant (buy 2 gal of full coolant and 2gal of distilled water to dilute). If you have flushed your truck lately then follow inst. below.

I'd buy a gallon of full and then a gallon of distilled to dilute 50/50. You'll probably only need 1 gal, but best to be safe. Also you don't need to drain fully. Take the hoses at the t-stat neck off and bed up IMMEDIATLY. this will keep your heater core from draining on you. then take 1/2 gal out the bottom of the radiator to help the head drain. Swap your t-stat after that and reassemble.

 

No, you certainly don't have to empty the cooling system to just change the thermostat. I would just remove the radiator cap to relieve the pressure. Remove the top radiator hose from the thermostat housing to make things easier to work with. Take out the bolts holding the thermostat housing and pull it off. There will be some coolant come out. I take my finger and slosh out a little more coolant so it doesn't get on the new gasket. Scrape the gasket surfaces clean. Apply blue RTV gasket sealer to the new gasket, Anti-seize on the bolt threads, and install the thermostat. NOTE: the thermostat sits sideways, not flat, so you have to be extremely careful to get it in there so you don't break the housing.

 

Thanks guys, I'm doing this tonight and will update once I'm done.

 

Alright, replaced the Tstat and I got a reading, its working fine now. I was stumped for a day trying to figure out why the radiators top hose was hot but the intake manifold would stay cool, even the heater worked well, it took a while but it did the job.

I did find one thing that may be a symptom I didn't read about. when I went up snowboarding and came back down, I exited the freeway after a 45 minute drive down hill, and my engine was reving up way high, for no reason. I pulled over and popped the hood expecting to find the throttle cable off the bracket or something, but there was nothing. I finally got back in my truck and the reving had stopped...

Could it have been that the computer was trying to warm up the engine by idling really high? Or is this a whole other issue coming up? It never did it before and it hasn't done it since. Thanks