Odd cooling system problem...
 

I have done an extensive search and I dont' see anything to help me with my problem. I am leaving tommorow for a 2200 mile trip, and obviously can't have any cooling issues.

My car (1994 Trans Am A4 with 106000) began running a little warm about three weeks ago, about 210 from the 170-180 it had always ran at. We suspected the thermostat. So I ordered a new 160 degree Hypertech. This did not fix the situation.

Next we replaced the factory waterpump with another brand new AC Delco waterpump. We bled the system until no air bubbles were present. I drove it for about 20 minutes and no problems, car ran at about 185 degrees at 60-100mph of highway/tollway driving. The car began inching up the temp scale as we began slowing down into city driving. IT crept up to just under 210. Drove about another 5 minutes to the house and let the car sit. It got all the way up to about 230-235 :eek: I adjusted the bleeder screws to no avail and the passenger side fan came on at about the 230 temp spot. This cooled the car back down to about 215 degrees.

I shut the car down and about two hours later, the very same events happened. Drove fine at highway speeds (~185 degrees). Got to two stop lights, and within 2 minutes the temp was reading 210. Got to work and let the car just sit. At about 230-235 (about 2 minutes of wait time), the passenger side fan came on.

What could this be? I have not checked the driver side fan (one suppose to come on first). Could this be it? Or possibly the factory radiator cap?

Guys, I am at a loss here and I am desperate. We leave tommorow and this has to be fixed.
THanks

Couple things to check...

is the cap any good? If it's questionable just replace it...people dont replace them as often as they should.
is there anything (like a bag) in front of the radiator? That happens sometimes.

slipping automatics can cause this problem too, or high stall converters not running an auxillary cooler.

Both fans work?

Stock programming has the fans coming on pretty hot. Even with the thermostat you need to reprogram the computer for this.

is the A/C on?

try using the heater on hi to help cool the car off when it's running hot to get a better idea...

Are you serious that a slipping tranny can cause that? :eek:

I think I began to feel it slip somewhat. Just kind of very slow at shifting gears.

I am going to replace the coolant sensor in the left side of block, new radiator cap and check both the fans tommorow.

If none of these fix it, could it really be the tranny?

Aside from your saying that it did not used to run as hot, it sounds relatively normal. Temps are going to rise as the car slows and you get into traffic because of loss of air flow. The fans don't come on until 226°, so it's going to look like it might be too hot, when it is really not. If the temp goes back down after the fans come on, then it's doing the job. You might want to double check that driver's side fan, though.

In my car, both fans come in at low speed first (series wired thru the relays) and if the coolant keeps getting hotter both will go at full speed ( paralell ). Supposing you have the same wiring, if one of the fans was open circuit (disconnected or bad), then only one fan would come in at the second stage setpoint (234 deg). Sounds like your problem.

Thanks guys. So if I check the driver's side fan and it is working properly, change the coolant temp sensor and replace the radiator cap, then that should (for the most part) signal that everything is okay?

Thanks again, please wish me luck as I don't want to take the 2004 Nissan Altima on the Hot Rod Power Tour :D ;)

Here is a little update:
Took the car to grab a bite to eat. Got it up on the highway and the car stayed at 185 degrees. Climbed to 225 in line, but quickly came back down to 210 after the fans came on. Then back out on the highway, the temp went down to 185 again.

SO I guess everything is cool. Thank god.