Brrrr No Heat

[Dawizman]

I'm new here. I recently bought a '96 Firebird. Its just the base model with the 3.8, 5sp, red.

Anyway, I'm having an issue with heat. The car heats up a bit during stop and go -traffic (well, the gauge makes it about 1/4 of the way up) and warm air gets blow out through the vents, but once I get on the highway, the temp gauge works its way back down below the minimum temp on the gauge (75 I think) and the air getting blown out isnt very warm at all.

I'm thinking its either an air bubble in the system somehow or it may be low on coolant. I have the thought in my head too that the t-stat might be stuck partially open or something too.

What do you guys reccomend I check out to help find the source of the problem?

[96Camaro]

hmm....I'd bleed out the system and change out the t-stat for starters and see if that works.

[Dawizman]

I guess another question that could be related. The front bumper has the two "slots", in lack of a better work, in it. Now If I remember correctly from my moms firebird, those are supposed to be blocked off, aren't they? I notice that on mine, it appears that there is definately something missing in there. I'm thinking that mabey too much cool air is hitting the rad and not letting it heat up. (Its been about -20* celcius lately).

[thenuge876]

i think if there were a bubble or you were low on coolant that would cause over heating (lack of coolant = lack of cooling) but based on the temperatures yoou described (and im really just guessing) maybe its just that when your moving at higher speeds the air is so cold out that the radiator can't heat up enough do you have a lower temp t-stat or is it the stock one?

[TraceZ]

hmm....I'd bleed out the system and change out the t-stat for starters and see if that works.

I agree.. Change the thermostat, fill it and bleed it.

If that fails, the core may be plugged and we can address that if need be later.

[Joe K. 99 Zeee!!]

Before you go out and buy a thermostat, test the one you have. Put it in a pot of water on the stove bring the heat up and see at what temperature it opens. I think the stock thermostat in the 3.8 V6 opens at around 190 or 195 deg F. The water shouldn't start to boil till over 200 deg.

[Dawizman]

How hard is it to get at the thermostat on the 3.8l in these cars? I havnt been able to find a haynes or chiltons manual around here, so I have no idea.

A bit off topic, are there any repair manuals for these cars online?

[TraceZ]

Before you go out and buy a thermostat, test the one you have. Put it in a pot of water on the stove bring the heat up and see at what temperature it opens. I think the stock thermostat in the 3.8 V6 opens at around 190 or 195 deg F. The water shouldn't start to boil till over 200 deg.

While that does work, I guess it all depends on how you feel about a few dollars. For me, If I suspect a cooling problem and am going through the work of pulling the thermostat I'm going to replace it with a new one no matter what. They are so cheap, once you've taken the time to remove it and boil water you might as well replace it IMO.

[96Camaro]

Yea, its just cheap insurance to replace the t-stat anyways. Instead of having to pull it again later.

[96Camaro]

Oh, and on the coolant issue. My car was low on coolant and it had a hard time getting heated up. But it never went above normal operating temps. So I think in cold weather low coolant may not always be as noticable.

[Jeff_in_Atl]

These cars are notorious for the heater core getting clogged because of the red GM coolant. You might want to back flush it when you change the thermostat. Cost=free=good

[Dave M]

the reason the temp gauge was low if you're low on coolant could have been because the coolant temp gauge was exposed to the air, if their wasn't enough coolant in the system to cover it. It's been known to happen. Your car could have actually been overheating and the gauge was being influenced by the outside air temp.

[Jeff_in_Atl]

the reason the temp gauge was low if you're low on coolant could have been because the coolant temp gauge was exposed to the air, if their wasn't enough coolant in the system to cover it. It's been known to happen. Your car could have actually been overheating and the gauge was being influenced by the outside air temp.

That's a good point. No coolant means no water to flow over the heater core which means no heat too.

[JL8Jeff]

I had to backflush the heater core every winter on my old 93 if I wanted any real amount of heat. It definitely made a difference and I was running the 160 t-stat all year round because of the chip and supercharger. The heater cores definitely get clogged up in these cars. If you're changing the t-stat, might as well backflush the heater core while it's drained.

[Joe K. 99 Zeee!!]

While that does work, I guess it all depends on how you feel about a few dollars. For me, If I suspect a cooling problem and am going through the work of pulling the thermostat I'm going to replace it with a new one no matter what. They are so cheap, once you've taken the time to remove it and boil water you might as well replace it IMO.

Well, maybe I emphasized the price too much. Still it's better to know if that the problem or not. At least you could narrow down the cause. Heck it could even be the unit sending the temp to the gauge, right? Who knows...

I've seen overheat conditions, but never an engine seeming to be running too cold.