Okay I was having problems overheating a few months ago. Here is what happens.

Car drives fine on highway speeds. When you slow down to traffic it slowly creeps up.

What I did to attempt to solve the problem (not in this order).

New waterpump
New sensor on the waterpump
New 160degree Hypertech thermostat
Blocked off my heatercore. I ran the two hoses together so it eliminates going in my firewall.

After I did this I noticed that my fans still were not coming on. So I tried reseting the PCM, no luck.

As I needed to drive this car everyday I just went ahead and installed a fan switch.

However I wired the fan directly and could not get both fans to turn on. Only one fan would turn on at a time for whatever reason. So I've got the highspeed fan running.

This solved my problem for a while, and still does. Provided I don't sit in stop and go traffic for a VERY long time it stays relatively cool. 170 on the guage. However if I do get into a bad situation you can literally watch the needle dive almost as fast as the speedometer goes when I nail the throttle.

Heres a recap of things tried


New waterpump
New sensor on the waterpump
New 160degree Hypertech thermostat
Blocked off my heatercore. I ran the two hoses together so it eliminates going in my firewall.
Reset PCM
Installed Fan switch
Tried to remove the air pockets, but I might have done it wrong.


Now questions:

Is one fan sufficient for south texas heat? I used the left fan as it seemed to spin the fastest

How in the hell do you remove air pockets? No one could give me a definitive answer. Some would say do it while the car was on (which just causes water to spray out). I tried like 5 different methods, none of which worked. I asked the guys at autozone and they just looked at me like I was speaking french.

Come on I can change an opti in under an hour, this is really pissing me off.

Thanks for any help.

- Z28WannaB

 

To get rid of the air pockets:

1. keeping radiator cap off radiator, top off radiator with fluid, start car.
2. continue waiting till you see the fluid level drop (thermo is open)
3. top off radiator again, open bleeder screw #1 located ontop of the thermostat housing
4. top off radiator again, till steady stream flowing from bleeder screw, close screw.
5. put radiator cap back on
6. keep motor running for a few minutes to build pressure in cooling system.
7. Shut off motor, open bleeder screw #2 located on heater hose. Coolant will spray out with pressure, so be careful. Wait till no more air is venting with fluid, close bleeder screw.

Done.

When's the last time you had it flushed? On my 94 w/120k miles on it, I bought the prestone flush kit, and back flushed the system. This yeilded the best resaults as there was a lot of suit in the heater core/block. (I'm still cleaning it out to this day)

For the best in cooling, have your PCM reprogrammed to turn the fans on @ 90C(low)95C(high) or with mine, 90C fan1 | 95C fan2

 

I'm having the same problem as you, and am looking into my radiator as the culprit.
I shot a pyrometer at the inlet hose, and the outlet hose on the radiator,
and it was only cooling the coolant 6* as it came out of the radiator.

 

I'm having a similiar problem but I know what it is. IF your fans turn on with the A/C but won't turn on otherwise, it is probably a bad sensor in the water pump. There are two sensors for getting the temperatures of your motor.. one in the head that goes to the guage and one in the pump that goes to the computer that tells it when to turn on/off the fans. So if you can get the car scanned and see what temps that sensor is reading do that, or just go ahead and replace that sensor.

Should be part #15326386

 

I replaced the fan switch sensor. But get this, it didn't do anything to solve the problem.

So I setup my fan switch on my connector using a diagram I found on the web and it still wouldn't turn on. So I just ran the fan switch directly to the fan.

- Z28WannaB

 

when I originally started having problems with my fan, I took it apart, and found the brushes had been bumped off the commutator. I just bumped them back into place & they both have worked for the past 5+ years. one comes on at like 210* or something stupid like that. but I usually turn the air conditioner on before it gets that high, and the one fan will bring it back down to normal.

 

Blocked off my heatercore. I ran the two hoses together so it eliminates going in my firewall.

Just wondering why you did this, with the heater core hooked up and the heat on high it will act as a supplemental radiator and help keep the engine cooler.

One fan is enough as long as the A/C is off, the non-A/C cars only came with one fan and this is enough.
Have you tried jumpering the fans to run all the time, I did this with my then ran it though a toggle switch so I could turn them on all the time. I just finally found out why mine was overheating all the time, the water pump drive shaft gear is stripped and not turning the pump. Before it finally quit alltogether the temps were running high even with the a/c off and both fans on, also there was a metal griding noise. Just hope yours is not starting to eat away the gear teeth. Also make sure there is nothing clogged up in front of your a/c condensor, take off the shroud, I found a bunch of crap build up in there over time.

 

When I open the radiator cap with the car on water starts to slowly over flow.

- Z28WannaB

 

Check the ground wires on the fans. They are mounted on each side of the radiator support

 

Mine does that too. So I keep the AC running. with the AC on, one of the fans is constantly on, and keeps the Thermometer in the car reading about 190*. then, the water level gets up to the neck, and stays there.

I've never been able to open a bleed screw, with the car running. it usually sucks in air, and shoots the water out of the radiator cap.

my overflow bottle overflew yesterday, then the car started running hot. I could smell antifreeze, and now, I'm trying to purge my system, so I'm going through it all now too.

 

If any of you guys think it is possibly a clogged radiator, you can pull the radiator, take it to a radiator shop and they can inspect it. It cost me about $20.00 back in 1998 to have mine inspected in Hawaii. Mine was so clogged, they couldn't get a brush in to clean it. If they aren't too clogged, they can clean it to get flow going again.

Z