Can the coolant temp sensor be removed without having to pull the intake out? I'm having trouble getting it loose due to lack of space.

Before I start pulling things apart, when I turn the ignition on the temp gauge doesn't move. Shouldn't it read full hot just by turning the ignition on? (not starting the car?)

I'm assuming that sensor is bad because I noticed the guage just sits on '100'...even after driving for 20 minutes. The guage always displayed inaccurate but today it's nothing.

Sound like the problem?

 

On my car when I turn the key on it simply shows the current engine tmep, it never goes all the way hot. I'd replace the sensor to eliminate it as a variable and then check your guage...

 

the coolant temp sensor is for the computer - not your gauge. what you see on your gauge is read from the temp sensor in the driver side head, between #1 and #3 plug. i'd check that wiring first - may be disconnected or broken. if it looks alright, ground it out and see if your gauge pegs out. if it does, wiring is good. i'd go for the temp SENSOR after that. if you're still not reading very much, your thermostat could be stuck open. even if it might be fairly new.

KAM

 

thunderstick , thanks for telling me that. I didn't know that was there. Is it difficult to replace? If I replace the temp sensor, do you think that will give me a more accurate reading on the guage?

 

Is this the wire that should be connected to the temp sensor between plugs 1 & 3?



And...Is this the temp sensor?



Close up of sensor....



If all that is correct, I don't see how the wire connects to the sensor. Maybe mine is broken? Missing something? Does anyone have a pic of how the wire should look?

 

That is the sensor and the connector... it slides on, not snaps like others... it physically slids onto the sensor. If you look at the sensor, you can see how it gets bigger at the top. The connect fits around that part.

 

that's a piece of cake to replace, and if that wire is broke or disconnected, as it looks like, that may be your only problem. be advised, obviously, that if you replace your sensor, you will **** some coolant out of there when you replace it, so be ready to catch it and then top off your coolant again when you're done.

and yea, that's a slide-on connector, as already said. mine recently broke, too, and i ended up using my old plastic piece, but a new terminal that wasn't a gm part, but it was the same part, got from autozone.

KAM

 

Thanks. I got the wire to slide back on. Much easier than I thought. All that crying for nothing.

If I replace the sensor, do you think my gauge will be more accurate? Or is it a combo of the temp sensor & coolant sensor?

 

there is no love between the coolant temp sensor on the front of the intake and that temp sensor in the head. is it reading normal now? you need to check that first. if it seems you are not coming up to temp, it could be a couple of things and one is the thermostat sticking open. you can tell if it is cuz you can squeeze the hose somewhat. normally you can do that once the stat opens. until it does, that hose will feel hard as heck. the other issue would be that temp sensor in the head...

 

i tested the wire by grounding it and that's okay.
i replaced the temp sensor and the gauge is still reading too high.

the fan's still kick in...(once the gauge reaches the first red mark)

Any suggestions?

 

Remove the sensor and clean the threads with a wire brush, or wheel.

If the white subtance on the threads of the gauge sensor in the close-up picture is teflon type, or sealant the gauge won't operate properly because the sealant is interfering with the sensors ability to ground itself through its screw theads to engine ground.
All one wire sensors comlete the ground circuit through their screw threads.

The gauge doesn't provide a signal for the fans, one fan is controlled by the ECM using the coolant temp sensor (front of Intake,) the second fan is controlled by a preset (220°) temp switch on the passenger side head, it's also a one wire sensor like the gauge sensor, but its connector is identical to the knock sensor (at least it is on my 88'.)

 

i've heard those stock fan switches are 237* or 239* switches. i'd definitely get rid of that thing and replace it with a 200*on/185*off switch. that switch is located on the opposite head between #6 and #8. i have one of those switches, a high flow water pump, and a stock gm thermostat in my Z, and before this rebuild, never had a problem. once i turn the key on this rebuild, all that could change, but i don't expect it to, and sure as hell hope it doesn't...

KAM

 

The only reason they put that temp setting so high is because it makes the engine run hotter and that improves the emission control system. In other words it doesn't produce as much emissions, but if you adjust the temp with a cooler switch for the fan then it increases the car's efficiency and gives it more HP suposedly. This is the explanation I've read in these threads, don't quote me on it!

 

well, i just burned my own chip and programmed the fans at 200*on/185*off. It's doing what its supposed to do but my temp gauge is still not accurate. It reads about 20* higher than the actual temp and i've replaced the temp sensor (between plugs 1 & 3) with a new one. think i have a bad instrument panel? all other gauges read correct.

 

How do you know that for a fact? Do you have another gauge? Do you have a digital dash? Are you comparing your gauge in the car with another one? It may be working just fine. Just some ideas here. Only my worth...

 

I had it hooked up to a scanner. when the scanner read 199*, the fan's turned on and off at 185*.

When the scanner read 199*, the instrument panel temp gauge read 220*.

 

I've always heard that the OEM gauges in the instrument panel are not as precise as the good quality aftermarkets. Maybe that's where the whole problem is. Mine shows to be running hot at all times but the car seems to run just fine. I've had V8 GM cars for well over 20 years now and I've always repaired them since I was a teenager and let me tell you something, all my other cars could not have run "this hot" as my temp gauge indicates this GTA runs, which is well over 200! Again, that's only my two cents worth of opinion.

 

I'm confused, how can the fan do any cooling if it's turned on at 185°, and then immediately turned off? Sounds like someone has messed with the ECM programming.

Are both fans connected to the ECM?

I'd worry more about the scanner reading than the gauge, ECM CTS seems to be correct in this case, I'd just remind myself that the gauge is 20° higher, or replace it with a gauge with a better calibration.

 

Sorry for the confusion. What I was try to say is the fan's turn on at 199* and it turns off at 185* according to the scanner. This is how I programmed the chip.

I agree with you rgarcia63, i pretty much need to remind myself the gauge is reading 20* above. I was hoping to have it accurate without buying anything aftermarket.