Have not driven my T/A in awhile but this weekend I decided to joyride a little and today I drove it about 80miles out of my city to visit a friend. All these miles are 100% hiways and little to no stoping. Temp gauge usually stays at just under 220 all the time untill I get on the hiway for awhile and today it almost hit 250 degrees. I noticed that the temp sending unit is pretty close to the headers and I was wondering if anyone elses gauge reads higher than it should because I dont think it's right. I used a brand new sending unit when I rebuilt to motor. I figure as hot as it is outside here in Fla that sitting in rush hour in 96+ temps would make it over heat quicker than driving hiway.

 

Probably not, the temperature sensing element is sticking right into the water jacket.

 

go check if you have all of your radiator airdam.

 

I've been dealing with this as well recently. Mine will only rise above 220* if I'm going <40mph and it's 95* or higher. What it does is get to just underneath the red, and the fans will kick on, and bring it down to 220*. Yours should not get above 220* if you are crusing on the highway. If you come to a red light, however, the temp will quickly rise. If yours is getting that hot while crusing, then check your radiator air dam. Then you might consider testing (or just replacing) your thermostat. 195*should be a good temp, but if you want to get a lower one, be my guest. Just realize that, if you have a lower temp thermostat, the car is still gonna get hot at red lights unless you reprogram your computer to change the fan cut-on settings (or have a chip that changes fan cut-on settings). Hence the reason why I'm picking up an Autoprom.

 

I have an 84' so I dont have the electric fans and I did use a new 195 t-stat. The car doesnt go over 220 in normal traffic or redlights, just on the hyways. I changed out the stock clutch driven fan for a flex fan but this problem was happening before that... The only thing thats not new is the water pump but it did work before the motor was rebuilt.

 

You'd have been better off with a properly working clutch fan instead of the flex fan.

 

My Z-28 does the same thing. After putting the SLP headers on, the stock temp guage goes wild on the freeway. It's not running hot though, 'cause I added a pillar-mounted Autometer guage with a sending unit mounted in the intake manifold's water passage to double-check it. The pillar guage reads between 180 and 210. So I think the stock one is affected by header heat or there maybe a short in the wire somewhere.

 

Your the first person I've heard that from, everyone seems to like their flex fan. My problem started before I added it anyway so I dont really see where it's a real big deal. The heavy and bulky fan I'm sure drags down the water pump. I did what KnightWarrior did and poped in a mech temp gauge and ended up with the same results he did, doesnt go over 190, so my guess would be that the headers are creating a false reading or there is a bad wire.

 

Flex fans were a good idea 40 years ago when cars had fixed mechanical fans. The heavy and bulky clutch fan doesn't drag down the water pump, because the thermal clutch is only driving the fan when hot air is coming through the rad, and the clutch slips so that the fan turns slower than the engine.

 

The Temp well be different from the heads to intake .I thank the intake would be best right before it go back to the rad.

 

if it helps, ive decided that all mechanical fans suck on thirdgens, and the only approprate fan is electric.




did you check with that gauge on the hwy?


on these cars, the ONLY thing forcing air thru the radiator, is the airdam.
at hwy speeds, if you dont have all of it there, you can start to overheat.... but it stays cool at idle because the fan pulls enough air thru.


something to check.

 

Is the temp sending unit the original one? Mine went bad and was registering way higher (about 20 degrees) than the car actually was.

 

Sorry, yes, I should have replied back before on that, yes, the airdamn is all 100% there.

 

My airdam is there also, in perfect shape. I really think the headers are cooking the sender. The guage works fine when you start it up and drive around town, even rises and falls with the thermastat opening/closing. But when you drive high-speed the stock guag flips out!!
I'm thinking of hooking my pillar guage's sender to the stock hole in the block and see if it misreads overheating too. If it does, then I'll know for sure the header heat is the culprit.

 

Has anybody checked the actual gauge in the dash. These are notorious for giving false readings. I just got done working on a 94 Z28 that said the temp was just below redline on the gauge after the car had completely warmed up. Testing the cylinder head sensor showed no problem. The P.C.M. said the temp was normal and a gauge hooked in place of the cylinder head sensor confirmed the normal operating temp. That only left one culprit and that's the gauge in the instrument cluster. Just my

 

Well, our cars, at least mine, is 20 years old. So a mis-leading gauge is not out of the question. I still think GM puting the temp unit in the head was a really bad idea.

 

Actually, my stock one has been replaced with a digital one from Jupiter electronics. It might be a loose connection or header heat. Either way, I'm not going to worry about it. The pillar guage is an Autometer analog nd works fine so I will just watch that one and disregard the dazzling lightshow in my digital bargraph.

 

 

well, you know, GM, ford, dodge and even rover V8s have had their temp sensors there since around the early 1960s.........



cant be too bad of a spot.

 

Well, the 5.0L Ford motor had theirs in the intake manifold.

 

years ago my brother overheated his 72 Nova (350) on the highway because his rear gears were so low (4.56:1) and he only had a three speed automatic. He was crusing at like 3700rpms. I don't want to sound sarcastic, but are you in overdrive on the highway? or which ever is the transmissions highest gear in your car?

Oh, and the temp guage in my driver side head reads 200F when my temp guage in the intake reads 215F. there could be a temp difference or calibration error.

 

the 3rdgen camaro has one in the drivers head for the gauge
one in the manifold for the ECM
and one in the other head for the fan turn on.

..... if you hook up matching gauges to each location, you'll get slightly diffrent temps.

 

The 5 years i've owned my car, I was always under the impression I had a 160 stat. Well I hooked my laptop up to my car, and at operating temperature my gauge shows 160, but the ecm says its at 190.