Well I am kind of getting pissed at this car. Ever since I moved out here its been one thing after another going wrong. The water pump died, alternator, and now BOTH the transmission AND differential decided to both start leaking within a weeks time of each other. Apparently these cars DO NOT do very well in desert climates. Well, I want to address the overheating issues I am having. Basically if Im not moving, the car will inevitably overheat. Today when I got home the car was sitting pretty at about 245-250 degrees, I decided to look under the hood at the fans. The drivers fan was going, but the passenger was not. Now my understanding is that the passenger fan is supposed to kick on when the A/C head pressure reaches 233PSI, OR when the coolant temp reaches 234 degrees. Now like I said before, the temp gauge was reading about 245-250 and this fan still was not on. I did not have the A/c on. Tomorrow I will let the car idle and watch the fans To see what exactly is going on. To me, I think that it is absolutely stupid to have two fans in the car and only have one come on when the car is practically overheating already. Considering how hot thirdgen cars run both of these fans should be coming on at the same time to keep things cool regardless of A/C usage. Well anyways, I am going to attempt to install a 160 t stat along with a Hypertech thermomaster chip I have laying around. is Anyone else running this set up? What temperature does your car stay at when it is 100+ degrees outside?

Only 100 degrees is a cool day here. Its been over 100 for the 90 days, every day.

Do you have the air dam underneath? Have you flushed your cooling system? Have you checked for debris between the rad & the AC condensor?

I was going to ask too, is there a performance/racing radiator that is a drop in replacement for the stock unit? Could some one give me a link? I want this car to run as cool as possible because right now, If I get caught at a really long stop light this cars temp goes to about red-line. That is defiantly not acceptable even if it is the desert.

Yeah its been about 108 everyday since I got here. I do have the dam on it, and the coolant was flushed when the water pump was replaced a couple of weeks ago. The radiator is totally free and clear of debris.

I've seen the passenger fan take a dump a lot. Just throw the A/C switch on and see if both fans run. If not try and spin the fan. If it's tight, it's history. You can also plug the driver's side into the passenger fan to see if it works.

These 3rd gens run hot from the begining. Since the fans don't come until 234*, it's hot. You can use a custom chip that turns the fans on sooner if you want. My friend that worked at GM proving grounds told me long ago that they ran these cars on the track in 110+ degrees and on the streets for long periods of time and for me not to worry about it if it's 230+ unless it goes way over sitting and doesn't come down when moving.

yeah tomorrow I am going to let the car Idle with the A/c on and see if it comes on.

The passenger side fan, will turn on with the AC switched on, regardless of how hot/cold the engine is.

Turning the AC on, turns that fan on too.

i use a hypertech fan switch with a 160 t stat very rarely do i see 200 but then again im not down in tx either and for some reason BOTH my fans come on together

OmnipotentGoku = El Paso, Texas

El Paso, Texas = "Sun City"

Sun City = 308 days of sunshine a year

308 days = great driving weather but generally 95- 100+ degrees (dry heat, no humidity)

Hot days + L98 TPI IROC = Cracked heads once when my fan stopped working.

Solution = One large cooling fan from a Thunderbird SC, wired to run constantly + Summit Aluminum Radiator.

Result - generally consistent 179 degree's and around 190 max when im on it.


Just a possible solution.

If you do stop and go traffic alot there then you might want an electric cooling pump. The cool trick you can do with an electric cooling pump is run the pump with the engine off.
Sounds like you might want a manual switch for your fan(s) maybe even add pusher fans.
With my car I use a 21'' factory fan on an improved factory shrowd and a 12'' pusher fan. I do not have an air dam and have some problems staying cool on the high way, but I have no problems what so ever in the city, where I do nearly all my driving.
If I were to move out there I would slap on 2 more 12'' pusher fans with a manual switch and expect to not have any problems.
On my diesel suburban I have a total of 4 electric fans: The main 16'' electric puller, a 12'' back up puller (both on a very well made home made shrowd) and two 12 inch pushers. And guess what, I have never had any cooling problems.
The main fan in both vehicles have a temp switch back up in case I forget to turn them on and every thing else is on a manual switch.

Well I put in the hypetech chip today, and it is better from what I can tell. It stayed around 200 and I was driving it kind of hard.(I did 120mph on the freeway this morning) I noticed that it made the throttle response better also. It is not the junk you guys made it out to be... But anyways I still am going to put in a new thermostat but I changed my mind on the 160, I am going to put in a 180 and see how it goes. The car runs great with that chip in it though.

220°F for the ECM controlled fan. 238° for the one run by the fan switch.

Delco D1855B (or equivalent) fan switch, 210-215°F on, will make both fans run roughly at the same time.

There is no reason a stock motor should need 4 fans to keep it to a reasonable temperature.

A 160° thermostat will solve nothing as well, unless the current thermostat isn't working properly. I like to use the MrGasket thermostats. They used to be sold at AutoZone under the Robert Shaw name. Advance Auto is where I picked up my latest one for my p.o.s '91.

If the pump is new, the hoses in good shape and the thermostat is working as is should (opening all the way), there shouldn't be much of problem.

The few things I would check is, are both fans working. Obviously one of the more vital parts of keeping the engine cool.

Is the condenser clean (road dirt, bugs, etc) and are all the fins mostly straight. The rare times I wash my '91, I will run the pressure washer under the front as well to wash the condenser. If air can't pass through the condenser, it's not going to get to the radiator either.
Same goes for the radiator. If dirt is built up on the cooling fins, it won't transfer the heat as efficiently.

How clean is the inside of the radiator/cooling passages of the block. If there is rust, scale or, sludge built up in the motor/radiator, it will reduce heat transfer as well. A flush is not the same as running the old coolant out of the block and putting in new water and antifreeze.

What is the coolant mix. A 25/75 mix is better for hot areas. Antifreeze is not as good at conducting heat as water is. In the cars I owned that I knew would run hot, I've always used Red Lines 'Water Wetter' as well. *useless side story* My old '76 3/4ton 4x4 suburban with a 400 showed the best results. The body lift made the mech fan useless (no shroud) so, I put 2 electric fans from a v6 Dodge Dynasty on it. They worked well enough but, with such a hulk of a vehicle, on hot days (95°+) is would still get a little temperature climb up towards 230° (180° thermo) in stop and go traffic. Putting the additive in the coolant made it run very consistently around 190° and on cooler days (80° or less), only one fan running was needed.

Is the radiator cap holding pressure and the seal good. They are cheap enough, I tend to replace mine every couple of years just to not have to worry about it.

None of the above may be of any help but, it's where I would start looking if I had an overheating issue. There is a reason the cooling system has lost it's efficiency.