96 Z28 runs warmer than normal at highway speeds
 

I've researched this online and in these forums, and have done pretty much everything suggested, but can't resolve it completely (have a 96 Z28, LT1, 99% stock):

Water pump failed and replace with new pump. Refilled system, bled air, replaced serpentine belt, replaced thermostat. Also flushed entired cooling system. Air dam is in place, cooling fans work correctly, hosed down front of radiator. There are no obstructions in front of radiator.

After all of this, temp gauge will move up, just below middle mark on gauge. Does not overheat, but runs warmer than it did at 70mph before I changed pumps. Also of note, this happens almost exclusively during the day/late afternoon. I went to class last night at 4pm and it went up a bit (though not to the middle mark). Came home at 10pm (sun down) and it was at the 1/4 mark the whole way. Also, this occurs with constant driving speed, not stop and go.

When sitting for long periods with A/C on, will remain very near, if not on the 1/4 mark where it's supposed to be. I'm also in Florida where it is still quite warm/hot.

Maybe I missed something I don't know, but that's why I'm here. Any help/suggestions are appreciated.

---Nathan

What part of Orlando are you in? Maybe I can take a look at it for you. I live about 5 minutes down the road from UCF Main Campus.

your radiator could be clogged
how many miles on it?
matt

I'm pretty close to you '94 Bad, 1 mile east of the 408 just off 50. I won't have time to look at it til tomorrow at the earliest but your offer is appreciated if it comes to that.

Matt - 170K miles on it. When I flushed the system, it ran clear towards the end, there wasn't as much garbage in there as I thought there would be. Figured that was a good thing.

Looked at it again this morning. Gauge sensor appears correct. One thing of note is that the coolant hose that goes from the passenger side of the radiator to the water pump inlet (w/ the termostat) starts to bulge within a couple minutes of starting the car, around 165 degrees or so. When up to 210 degrees, continues to bulge quite a bit. So I turned the A/C on to turn the fans on and it took it back down to 180/190 degrees.

Any idea if there's a cause for the bulging hose, besides just a degrading hose? Would this hose cause it to run warmer than normal on the highway?

Guess I should also mention the radiator appeared to warm throughout (top/bottom, and left/right). After 180 degrees was obtained, the radiator hose in question did get warm/hot after thermostat opened.

How sure are you that the reading on the guage is correct? Might be worthwhile to have a scan tool connected and see what temp the ECM is reading (as it uses a different temp sensor from what the guage uses IIRC. This can be done with OBDII, not sure on OBD1) or hook up a mechanical temp guage and see what it reads under the same conditions.