I am having an oveheating problem at idle. As I sit with it idling in gear or park the temp climbs and climbs until I get some airflow or I turn it off.

I have verified both fans are turning on at the right time.

I am thinking this might be a result of too much timing advance at idle.

Could having 30+ degrees of timing at idle cause an overheating problem?

Thanks.

 

No.

To the contrary; NOT ENOUGH timing advance can cause oveheating.

30° sounds in the ballpark.

I don't see anything in your post that indicates that anything is "overheating".

What makes you think that it's "overheating"?

 

Um I dont understand your question. What makes me think its overheating is when the temp gauge moves toward 230...

 

Make sure your radiator is full. Mine was overheating (200-225) at stoplights. I had a small unoticable water leak at the heater control valve on the heater hoses. Changed out the valve, filled the radiator back up, no more overheating. Running steady 165 with the A/C on.....and it's HOT down here in south central Texas.

 

Rad is full - resivoir is at proper level. Just checked today.

 

NOT overheating.NOT overheating.

The fan switch in these cars DOESN'T EVEN TURN THE FAN ON until about 235°. In other words, as far as the designers of the car were concerned, the engine DOES NOT EVEN NEED COOLING AT ALL until it reaches that temp. Not that the people who built the car would have a clue what the car is supposed to do, or needs to do; but, whatever.

In other words, 230° is COMPLETELY NORMAL. It is not overheating, not unusual, not a problem, not anything wrong at all.

When driving down the road, the temp should stay just slightly above the thermostat opening point; around 200. When you stop and sit still, the temp should rise to about 235°; the fan should come on; the temp should descend; when it reaches the fan switch's shutoff temp, about 215°, the fan should {drum roll please} shut off; the temp should begin to climb again; when it reaches 235°, the fan should come on; etc. It should sit there and do that for hours on end, if the car deosn't move; until it runs out of gas.

I don't see anything in the case of either of your cars that sounds even remotely dimly nearly vaguely close to "overheating".

 

I can certainly understand some of your frustration as I did not tell you that the motor had a 170 stat and a fan switch to turn on both fans at 185 and off at 170.

But really my question about too much timing was the one I wanted answered. I dont believe I ever asked "is 230 normal". I am firmly convinced that the temperature would keep climing if I let it but I dont.

Now I am beginning to wonder if the "high flow" 170 stat I put in is not letting the coolant stay in the radiator long enough at idle? or maybe the placement of the fans on the radiator. I didnt cover all the core tubes but instead put them side by side. I think I should have put them at the corners between the inlet and outlet.

In any case the idea that I dont want the motor to run as hot as it does is what I am trying to fix. Please limit your replys to keeping the temps under 200 at idle which is where I would like it to run.

 

Overheating at idle implies that at speed, airflow through the radiator keeps temps where you want them. I would guess that your problem is airflow through the radiator at idle.

You need proper radiator shrouding and dual fans close to the radiator to ensure enough airflow to keep things cool, since it was previously posted that GM did not design the fan system to provide enough airflow (in single-fan models) to keep temps below 215 with hot ambient air. If it was a thermostat problem, running the car at speed would make no difference. You are looking for something that changes with the car at speed, which is airflow through the radiator.

I hope this helps.

TA

 

Yes it does. I think I will try to reposition the fans to cover more of the core tubes.

Thanks.

 

Problem was solved a long time ago - sorry for the late update. Turns out that I had wired the fan relays to turn on through a circuit that lost power when the brakes were applied. Any time I had my foot on the brake the fans would cut out. If I put it into park it would be fine.

Changed wiring - problem solved.

 

Wow. That's going in the memory bank. So everytime you got out to check the fans they worked fine, but while sitting in the car, foot on the brake, the car overheated.

 

You got it!