Arctic_Z

I have a 94 z28 with just bolt on mods. headers, exhaust, cai, maf sensor, hypertech programming with 160 thermostat.
Today I went to wash my car. I left the car on with the a/c running because my daughter was in there and I wasn't going to be long. I did a fast rinse, climb in the car and my water temp was in the red. I put the car under the canopy to dry it off, turned the car off and opened the hood to let it cool down. When I was done I started it and proceeded to go home. I had to pull over to let it cool because it started to overheat again. I must have lost some coolent when it first overheated.
When the car cooled down I drove it home and the temp stayed at about 160-170. I got home let it cool down, filled it with coolant and drove around the neighborhood trying to get it hot. It just stayed at about 160. So I tried to take it on the highway. Immediatly it started to overheat again. I got it home and replaced the thermostat with another 160 thermostat that wasn't a hypertech. Didn't think it mattered. As long as it was 160 to go with programming. I let it sit in the driveway running and it stayed at 160-170. So I took it for a drive. Not even 3 minutes into the drive it overheated again.
I have a brand new waterpump about a year old with about 20,000 miles on it. My fans are working I can hear them kicking on, so I know it isn't a relay or fan motor. There are no leaks anywhere that I can see, the hoses look fine. The only coolant I see is coming from the coolant overflow lid. I checked my oil and it looks fine. No milkshake.
One of my buddies says it could be the intake. But I don't see any water anywhere around it. Anybody got a clue.
Thanks for any opinions.

SP2340

I've been fighting an overheating problem with my '94 Z as well. You said yours was only overheating when you drove it or with the A/C on, but was fine at idle. I would check for both good airflow across the radiator and coolant flow though it. It may be that you have sufficient cooling capacity for idle but not at highway speed. The fans should not matter on the highway anyway. I have found a lot of crap build up in front of the A/C condensor and clean it out every so often.

NewbieWar

for me, the a/c always keeps her cool... if the A/C is not on, it will usually keep creaping up, and wont go back down, unfortunatly the A/C usualy is very cold and sometimes at night its not pleasent to have that thing on.

but with your situation, make sure you dont have any bubbles in your block...

make sure you have plenty of coolant...

ummm but beyond that, i dont know what to say... I've always had problems in my firebird... (but i dont have a heater core, so i have less coolant then most i think)

NewbieWar

ohh its not a hypertech Thermostat? does any other company make a 160 reverse style thermostat?

hope you have the right thermostat...

ZMAN Z28

I can't say for certain if this is your problem. But it would't hurt to pull your radiator and take it to a radiator shop and they can inspect to see if it is clogged. It might be. Back in 98, my car started overheating. I was in denial it was the radiator. Sure as all get out, I pulled it and took it to a shop, and it was so clogged they couldn't get a brush in to clean it out. It wasn't expensive to have them inspect it. A brand new one was around 150, but that was 1998. Since I was in denial, I drove it around and it overheated, and I warped a head. So just something to think about. Also look and see if something like a piece of paper is stuck on your radiator. Crazier things happen.

Z

chuckd4more

I had the same problem as ZMAN. And I believe I have warped a head. It was my radiator.