Ok guys i just picked up my new ride...92 z28 5.0/auto. 28k miles. Had some problems on the long ride back related to sitting for awhile (rotted radiator caused huge coolant leak, bad fuel pump/fuel filter caused surging. AFter about $1500 at the chevy dealer in the town it broke down, it was roadworthy. They replaced everything--new fuel pump, fuel filter, new radiator, all new hoses and clamps, new air filters, new belt, etc. etc. etc.

The ride home was 530 miles and the car road seemlessly. At one particular tollbooth, the car seemed to heat up very fast as we waited in line. Much faster than i remember my previous 92 RS (305 TBI) heating up. It went from the cruising temp of 160F to about 220F within 1-2 minutes of slowing down/stopping. After a few more minutes it almost got up to 240F. That seems waaayyyyyyyyy high and wayyyy to fast. Also, right when we got off the highway just now to come home, we noticed it heated up to almost 220F. I mean there were just a few stopsigns and about 2 miles between the highway and our house, and the driving was pretty slow (30-40mph max), but the car shouldnt get that hot.

Please help me diagnose this problem, as it poses a problem to me because i dont really wanna drive it anywhere when i know it heats up soo fast at even the slightest stop or slowdown.

From what i understand the factory fan switch comes on at 225F? so tha tcould possibly be faulty if the car was reaching almost 240F...but neverless that still doesnt tell me why the car got to that 220F mark much faster than it seems it should (or atleast it did on my 92 RS, which had 45k miles).

 

Make sure the fan(s) are kicking on. TPI cars the ECM kicks on the fan at 228*F, assuming the A/C is not turned on. That usually reads as the hash mark between the 220 and 260 lines, not far from the "red." Most stock temp gagues rear hotter than actual (or hotter than the CTS tells the ECM it is, anyway).

Read all about how your fan system works in an excellent article on this website's tech articles section titled "Ultimate Fan Control". It's not only tells you about modifications to the system but also about how the stock system is SUPPOSED to work in good detail.

 

Scratch that- it's been broken into 2 articles. One for single fan systems (TBI engines) and one for dual fan systems (TPI engines). It's in the electrical systems part of the tech articles section.

The only thing I don't think the article clearly states is that the fans aren't turned on directly by the ECM/switces diescribed in the article. Those things activate RELAYS that actually supply high amp power to the fans.

 

Yea my dad (who thank god i have him...hes an ex-GM tech from the 80's who has taught me everything i know about cars) said that the gauge might even be off alittle bit. Its just scary with this car because we've already had problems and we're so paranoid about every little thing now its sickening.

Is it normal that this car seemed to get hotter than my TBI car??? I wasnt driving at the time so i couldnt tell you if it idled any differently when it got that hot.

The gauge did get up around the dash between 220 and 260 (the red). Is there any possible way that someone could take a picture of their TPI car's gauge when the fan kicks in and we can see what your gauage looks like?

Also, how fast do these things normally go from 160*-220ish*?? For us it seemed to do it very fast (less than a minute!).

 

The TBI engines kick the fan on around 215* (A/C off) so it'll read a little lower on the gague than a TPI car will, all else held equal. The gagues are notoriously inaccurate so comparing from one car to another is problematic.

If you have access to a scan tool use it and see what the CTS is telling the computer. I'd put a LOT more faith in that reading than I would in the stock gague/sender.

 

No, my dad has everything but that apparently, haha.

You've been outrageously helpful so far damon, but i have one more, very important question....How long does it usually take for the car to go from 160* (cruising temp) to 220*ish (standstill/slow driving temp). For us, it seemed to heat up to 220*+ in about 1-2 minutes while sitting at a tollbooth, and it seemed to get right up to (but not over) 220* when we got off the highway and drove to our house (about 2 miles consiting of a stop sign, about 70 meters and then another stopsign, 1/4 mile of 45 mph, then about 1.3 miles of 10-25 MPH driving).

I dont remember how fast my TBI car used to heat up...I only had the stock thermostat in it for about 2 months before i switched to a 180*..and before that, i never really payed attention to the gauges. Would putting a 180* in slow down how fast it heats up? Also, what is a fairly neutral fan switch that i can buy. I only wanna run 1 thermostate and 1 fan swtich (i liked the 180* t-stat), and would like something around its equivliant for the fan switch--nothing too radical, but better than stock obviously.

 

anybody??