Engine won't warm up, no heat

[JGood]

87 325is, installed a 99k mile m20b25 last year and put about 500 miles on it since. This is my first time driving it in cold weather. This is a track car converted for temporary street use, so all maintenance is up to date and the car runs perfect.

Except, the temp gauge never leaves the blue unless I leave it idling for a good 30 minutes, and even then it will only creep up to 1/4. I have a 1 hour commute to work, mixed highway, and stop and go. It never leaves the blue zone. The ambient temp this morning was 26 degrees, but the engine should be getting a bit warmer. It has no mechanical fan. Just an electric fan with a probe-style thermostat, which never kicks on due to low coolant temp.

I also get very little heat. It's warm air for sure, so the heater valve is working and the hoses are hooked up right (I had them swapped previously, and got no heat at all). But it's by no means warm enough.

I've bled it several times, I'm not getting any more air out of the bleeder.

I believe the gauge is correct, as my infrared temp gun doesn't show any excessive heat after driving for an hour (which I would expect to see, if there is air in the system). The rad hoses show about 170 degrees F before and after the radiator while idling for 30+ minutes, with no fan.

Any ideas?

[Ceeker]

replace your thermostat. take it out and put an 80 degree Celsius (176 Fahrenheit) one in.
That may be the only problem. if this isn't it, then check the flow of coolant in the rad. sometimes a partially clogged rad will generate the same problem. Once the car gets up to op temp. Squeeze the rad hoses for pressure. they should be quite hard and equal. Did you bleed the system with the heater on full? sometimes air gets trapped in the heater core or back of the block. It is also a good idea to bleed the car in a slight incline so that air can move towards the front of the block. Is your pre-mix of coolant correct?

[KenC]

Sounds like your thermostat is stuck open and the coolant (being cooled by 26 degree ambient air) is being constantly circulated. The heat from combustion is losing the battle.

[JGood]

replace your thermostat. take it out and put an 80 degree Celsius (176 Fahrenheit) one in.
That may be the only problem. if this isn't it, then check the flow of coolant in the rad. sometimes a partially clogged rad will generate the same problem. Once the car gets up to op temp. Squeeze the rad hoses for pressure. they should be quite hard and equal. Did you bleed the system with the heater on full? sometimes air gets trapped in the heater core or back of the block. It is also a good idea to bleed the car in a slight incline so that air can move towards the front of the block. Is your pre-mix of coolant correct?

Will do. That's the one thing I didn't do when I put the engine in, I left the thermostat alone.

The rad is pretty new, I had no troubles with it 500 miles ago, when I had the previous engine in.

Both rad hoses are equally pressurized and hard at 'operating temp'... but again, that's not very high.

The heater was on and the car was slanted nose-up while bleeding.

The mix is 50/50 with a bottle of Redline Water Wetter as well.

The thing is, the car never gets out of the blue zone, so a clogged rad, improper mix, or even air in the system wouldn't keep it to cold would it?

[jlevie]

I agree with KenC, replace the thermostat with a stock 80C unit.

[JGood]

I'll give it a shot. Thanks guys.

[JGood]

Put a new thermostat in, temp gauge now sits just under half and I get full heat. Thanks guys!

[KenC]

Put a new thermostat in, temp gauge now sits just under half and I get full heat. Thanks guys!

Nice!!!