Poor heat at idle

[Dxray]

For some reason, my 3100 doesn't put out much heat at idle, it's like almost lukewarm. But it i rev it over 2000rpm, then the heat is warm. The temp gauge always reads halfway. I know it's not my heater core because i had lots of heat with my 2.2 at idle or cruising. Would a cheap or 180* t-stat cause something like this? It's getting damn cold out.

[PCGUY112887]

I'm not sure what you mean, do you mean it does not warm up that much when it just idles?

If so, that is normal.

Temp gauge always reads halfway? Even when the car is cold?

[TazMan]

Check your coolant level.

[Superdave]

There could be an air bubble hanging out in the heater core lines...

[Dxray]

I'm not sure what you mean, do you mean it does not warm up that much when it just idles?

If so, that is normal.

Temp gauge always reads halfway? Even when the car is cold?

At idle, the heat in the car is not really warm. Don't see how that can be normal, i figured this v6 would have better heat then my old 2.2, not true at all. The heat at idle should be hotter then when cruising, not so in my case. The temp gauge is halfway at operating temp, doesn't change from idling to driving.

The coolant level is good.

After nearly 2000miles, an air bubble should have passed by now, no? I bled it when i filled the coolant, but it did take a long time for the car to get heat when we first fired it up. The car was at operating temp for a while before i got any heat in the car. Not sure if that has something to do with my problem now.

[19Cutlass94]

Well if the temp gauge is only at half way that could be a problem right there. At half way, the air is fairly warm, but wont really get cooking until it hits the 200* mark. Id figure out why your only running at half-way temp on the gauge.

[IsaacHayes]

LOL, my car runs under 1/4mark on the gauge when it's at operating temp. So you can't go by the gauge to know what temp it is unless you know your gauge and where it usually sits at. On mine a hair over 1/2 and the fan kicks on...

Anyways, you might have air bubble, the 3100 coolant setup is kind of hard to burp, even harder in W body cars since they lack the pipe coming from the thermostat neck going to a recovery tank. There they have an additional bleeder to open up.

To get my car bleed well I have always had to have it hot where the fan is kicking on and open up the bleeder and rev it a bit to help push out the air. I drilled 2 small holes in my thermostat and that helped A LOT to speed up the bleeding process.

If you have air bubbles the heat won't be as good I've had that happen. Also you should have heat even with 180F stat. I put in the stock 195F as I felt no difference in power if anything less response. From now on I will only go to a cooler stat if forced induction.

The v6 will take longer to get warm since it's bigger and has more metal/mass. All 4 bangers I've drove got hot fast.

[Dxray]

I think I'll need a mechanical gauge to tell me what temp it's really at. The gauge has never gone past half and I've never had the fan kick on, not even sure if it does work. From driving it, the gauge seems to work normal, but maybe it's not getting the right signal and not letting it get past half. Or maybe I'll try to measure the resistance on the sensor and see what temp it's really at, i remember seeing a chart somewhere.

Thanks for the suggestions.

[IsaacHayes]

Yes measure the resistance that will tell you for sure what's going on. Do you have the ALDL wired up? You can use a ALDL cable OBDI and TunerPro RT to log the OBD1.5 sensor data.

[CNCguy]

Do you have the correct thermostat in it? By correct, I mean does it have the spring and washer looking part on the end of it? If not the coolant can bypass the heater core when there is low flow like at idle.

[IsaacHayes]

That washer only seals off the coolant bypass that goes back to the water pump when the thermostat opens. So when it opens flow goes to heater core and radiator only. When it's closed it goes through heater core and back to the water pump to help heat it up quicker.

[IanSzgatti]

For some reason, my 3100 doesn't put out much heat at idle, it's like almost lukewarm. But it i rev it over 2000rpm, then the heat is warm. The temp gauge always reads halfway. I know it's not my heater core because i had lots of heat with my 2.2 at idle or cruising. Would a cheap or 180* t-stat cause something like this? It's getting damn cold out.

cover your rad in the front for the winter... my cars HVAC is good but it's not the hottest thing in the world...
your not over heating and your fans come on meaning everythings working ok... your good... but you need something to block the winter air so you can warm up a bit more... I used cardboard for god sake and I noticed a good difference... just have to remember to take it out in the spring

[IsaacHayes]

Shoudn't have to. My heat burns me up....

[TazMan]

A 180 degree t-stat shouldn't cause that. I just came back from a 3 1/2 hour drive with no t-stat in about 30-40 degree weather and I had pretty good heat the whole time. My temp gauge never reached past the first notch. I would think with your temp gauge up half way your heat should be plenty hot. When you're sure your system is bled of air, if the problem persists, I would suspect some sort of circulation problem.

[Dxray]

Ok, well i tried mesuring the resistance with no luck at all. I'm getting around 150-180 ohms at idle and 120-140 ohms while reving it. According to these values, i'm well over 220* and it's getting hotter when i rev it. What i did was mesure the rear 1 wire coolant temp sensor which is currently running my gauge. I dis-connected it and stuck the positive probe in the connector and the negative probe on the negative side of the battery and thats how i got those values. I'm sure i did not do this right, do i have to mesure the the 2 wire temp sensor under the tb??