Sorry....but this is getting frustrating. I've been chasing cooling problems (as with every other 3rd gen owner) since I bought it.

Stock rad with 195 t-stat, aftermarket fan switch, hi-flow alum h20 pump, dual fans, and no a/c.

Usually, in traffic it gets to 220-230 but never more. It maintains pretty well. On the highway, never more than 200 usually. But just lately I've been on some 3-4 hr road trips in 90+ degree weather. An hour into the trip or less I climb above 220 and my car cools like i'm sitting in traffic (220-230).

The good news is that it maintains a particular temp range and does not ever touch the guage mark that is between 220 and 260 (240* ??).

The bad news is that it runs at 220-230.

Is there any trick to running 20* cooler?

I thought the cheapest thing would be the 180 t-stat. Has this really helped anyone out? Maybe my stat is bad (2 yrs old).

It also bugs me that my 2nd fan comes on at 230. I thought about using the manual switch.

What do recommend?

 

I used to have that problem until I put an alminum radiator in it, my car ran around 185-190 all the time.

 

I think that is your problem isnt it, the fact that the fans dont come on until it hits like 220?

 

Yes the fans are a problem, but thats the stock setting right?

Except I tweaked the primary fan with an aftermarket fan switch to come on at a cooler temp.

Its the secondary that turns on at 230 or when the a/c is on.

 

I believe the only way your going to run cooler is two change the chip setting from 220 to what ever temp you want to run, period.

 

220* on the hwy does sound too high. After getting a coolant flush, 180* thermo and a new airdam, my car was running at 1/2 on the guage...nice and cool compared to before.

My first recommendation would be change the thermo or the coolant.

 

Really should run on the thermostat temp on the open road, especially without AC. Does your car not have the AC condensor in front of the radiator? Did the car have AC when new? I'd guess if the above is a no, you really need a new bigger radiator. If it has the condensor you probably need to remove the upper radiator support, clean out the area good, wash through the radiator and condensor with a good pressure garden hose.

 

I had the same problem on my newly acquired Z28, always running hot. I drained the cooling system, flushed it thoroughly, several times. I also took the radiator out and straightened all the fins on the A/C condenser (the bent fins were blocking, I'd say, around 15% of the surface). I put a 180 thermostat in and now I'm running at 180 all day. The only time it heats up to 200 or more is when I stop in traffic (cuz my fans are mis-wired). But again, I test drive it mostly at night so it doesn't get much time to heat up.

Flush your cooling system well, run it with straight water, flush it again, do that several times to get junk out of your engine (you won't believe what was in my block). Check A/C condenser and radiator fins.

Oh, one big question: are you running some K&N filter or something attached right to the TB under the hood? That was what I bought the car with. No wonder it was always running hot. I also restored the original intake system and that helpled as well.

Hope this all helps.
Lou

 

Yep....had factory a/c. It just doesnt run....bad compressor. So I dont have use of the secondary fan until engine temp reaches 230.

I thought for a while that it was due to a faulty coolant temp sensor. I dont know.

I'll prob get my coolant flushed and try to wash off the radiator fins first to see if that makes a diff.

Dante....when you say 1/2 on the guage, you mean dead center at 220*??


What is NORMAL operating temp on these vehicles. I mean, what did GM intend? I know they were designed to run hot for emissions, but from the factory, were they supposed to run at 220?

 

Hey we both have 91 vert Z28's and live in Texas. This hot weather sucks! I guess I'll break down and try the 180 stat, get a good flush, and make sure the rad looks good and see if it makes a diifference. What the hell.

 

Hey, what are the chances of that? Two verts, identical, exept maybe for paint. Mine's black, what color's yours?

Hot weather? We had a cold summer this year, never made it over 105F!

If you are anywhere near Austin, lemme know, I wouldn't mind helping you troubleshoot the cooling system.

Lou

 

:werd: no **** right.....

 

Your fans don't come on until 228 but when your on the highway your car should not get that hot. Check the air dam and everything else down there anything not right can cause this problem. Also a cooler fan setting is a $25 dollar fix. You can also rig both fans to come on at the same time ( free). Just do your research. I did and it works great!

 

I put in a bottle of watter wetter and it really does help it run like 10 degrees cooler.

 

How do you rig both fans to come on at the same time??


My car has been fine since the weather has been a few degrees cooler. But last night, I made a 5 min trip to wash the car. After Just a few minutes after driving after the wash, the temp guage read about 240-250, which it never does.

I pulled into a parking lot and shut it down and opened the hood to look for leaks. Nothing. But while it was cooling, I wanted to check my fans. Turned the engine, and looked under the hood. The primary fan wasn't even on!! Only the secondary (driver side).

I figured I had a burned out fan motor, so I cool it down and drive to Autozone. I get there, 220*, pop the hood and its just the opposite: Primary fan running, with secondary off (which is how it usually is). Drove around more without any problems. Steady at 220* in city traffic.

I don't know. The fanswitch is aftermarket piece. Either its a faulty fan switch, or a failing fan motor. But I'm not sure this is the cause of the problem since I have pulled over when its been hot before and the fans are working correctly.

Is it possible that the primary fan is only working intermittently?? Being lazy when I'm not watching?

 

It might be a handfull of things: fan motor, relay, wiring, switch, ground ...
If you are anywhere near Central Texas, lemme know, I can look at it. Also, I might be up in the Dallas area soon so I could maybe stop by.
And yes, a 180deg t-stat would help greatly.
Also, I have a 180deg switch that you can put on your block/intake/rad and use it to control the secondary fan relay. That would turn your aux fan into a primary fan because the ECM doesn't turn on the primary until 220+deg. It would improve cooling.

Hope this helps.
Lou

 

Like others have stated check the air dam, and radiator for damage. Then go to Sears, or someother auto shop and have them test your coolant, no sense, blowing money on a exchange or flush if you don't have to. Then the 180 themostat is a good idea, but don't use a 160, its not worth it. Next you can do one of three things, change the factory setting with a chip, wire the two fans to one circuit, as stated previous, or buy the kit and have an adjustable switch. And if that doesn't help then I don't know what to tell you.

 

I have one of those adj fan switches for the aux fan, but (I know this sounds stupid) I could not tell on brief inspection which fan wire was to ground.

What is the easiest way to install those things?

Lou......I'm in Bryan right now and may be able to make it to Austin in a few weeks (weekend of the 15th). I'd appreciate your help. My email is msh1115@email.com.

I don't think I'll have any time until that weekend. Lots going on right now. We'll play it by ear if thats cool.


I'm still confused about the primary fan not being on when its supposed to be sometimes. I'll have to trace all the wiring. Too bad I'm on the road and don't have my hydraulic jack with me.

On a side note: I remembered that my aftermarket fan switch is supposed to trigger the fan on at 200* and off at 185*. I went to the website and they recommend a 180 stat with that fan switch. Too bad I didn't pay attention when I bought it.

Unless my guages are jacked, I never run at 200*. Always 220-240. Ahhh.....frustrating.

 

Which Bryan ya talking about? The one by College Station or by Dallas? Cuz I'll be in the Dallas area soon (this weekend or maybe the next one).

BTW: you should not need a jack to trace the fan wiring. We'll take a look at it, don't worry.

Lou

 

College Station......I live in Fort Worth though usually. I'm just down here for another 3 weeks. This weekend is crazy , same as next....No time to work on it until the weekend of the 15th when I will probably be in Austin for some stuff I need to do.

Have fun in Big D!