engine and drivetrain Engine temperature always low, no heat

[asifallasleep]

I have a 1974 BMW 2002. The longest drives are around 30 minutes tops. I live in SoCal and the engine never gets hot enough to produce heat. Temp gauge seems to always stay just barely above blue. The car does have a larger 320i radiator. How quickly should the engine temp get to the midway point gauge wise representing normal operating temp? I don't know if i'm not driving the car long enough and/or if it's a thermostat issue.

[napa02]

what temp is your thermostat? or do you even have one?

[asifallasleep]

what temp is your thermostat? or do you even have one?

I thought about that this morning. The previous owner may have removed it this being SoCal and all. Going to check for it today.

[asifallasleep]

i do have one. i will have to remove it to see which one i have. i've heard a 80 is better for performance but not the best for older engines. i have a rebuilt engine with just about 6K on it. Not sure if there's a big difference between 71, 75 and 80. I'm leaning towards the 75 since i'm in a hot climate that does get chilly at night.

[Guest Anonymous]

I bet it's your thermostat; you probably have a 71 one, maybe a 76. It makes a difference. I had the same issue last year after I flushed the radiator; could barely get out of the blue zone. Turns out the T-stat was a 71 (it was an Arizona car), which is way too cold; swapped it for a 76 and I'm even thinking I should gotten the 80.

30 min is more than enough time for the car to warm up. And it's not good if it's running that cool. By the way, you don't have to remove the T-stat to see what temp it is; if you use a mirror you can read the engraving on it.

Good luck!

Hugh

[SteveJ]

That's one thing- 2002 heaters usually work pretty well compared to other 40 year old cars.

Chect the Tstat.

After the car has warmed up, give the two heater hoses a feel to see if they are both warm. Possibly disconnect the heater hoses, connect a legnth of garden hose, and see if it flushes out any crap. Don't use hish pressure, you just want to see if there is any flow.

How is the heater valve working?

[Napes]

I live in Southern Arizona, so I have a 71ºC thermostat. In the winter the mornings are around 32ºF +/- and, after driving for 5-6 min., I start to get heat. Except in 100º+ air temps my temp guage rarely gets much above the blue. After 10 min. of driving on cold mornings I get enough heat to get complaints from my wife about her feet cooking.

Maybe part of the problem lies with your heater core, but let's hope not. It's a little hard to change out - worse, if like me, you have A/C. As Steve J says above, check your heater valve to ensure it's working.

Bob Napier

[c.d.iesel]

your motor should reach operating temp (176 ....190*F)

in 8 ...10 min driving time. If not your not operating at

optimal temp they your getting gas fouled oil, moisture fouled oil,

poor performance, poor air/fuel mixture ratio's - go with the 80* stat

[Mike Self]

designed to fail in the open position so as not to cause overheating, so yours may have just given up the ghost.

If you want to test it, the best way is to suspend it on a string in a pan of water on the stove with a thermometer and watch the valve as the water heats. It should open within a few degrees of the temp stamped on the 'stat.

Or just get a new one.

mike

[asifallasleep]

your motor should reach operating temp (176 ....190*F)

in 8 ...10 min driving time. If not your not operating at

optimal temp they your getting gas fouled oil, moisture fouled oil,

poor performance, poor air/fuel mixture ratio's - go with the 80* stat

I've had the car for almost two years and the car has never had heat or risen much above the blue. Since i'm in SoCal, didn't really need heat, and as long as the car wasn't overheating I didn't worry about it.

Perhaps this may explain my poor gas mileage? (17mpg) I'll get an 80 and install it this week. Thanks.

[asifallasleep]

I bet it's your thermostat; you probably have a 71 one, maybe a 76. It makes a difference. I had the same issue last year after I flushed the radiator; could barely get out of the blue zone. Turns out the T-stat was a 71 (it was an Arizona car), which is way too cold; swapped it for a 76 and I'm even thinking I should gotten the 80.

30 min is more than enough time for the car to warm up. And it's not good if it's running that cool. By the way, you don't have to remove the T-stat to see what temp it is; if you use a mirror you can read the engraving on it.

Good luck!

Hugh

Thanks.

[asifallasleep]

designed to fail in the open position so as not to cause overheating, so yours may have just given up the ghost.

If you want to test it, the best way is to suspend it on a string in a pan of water on the stove with a thermometer and watch the valve as the water heats. It should open within a few degrees of the temp stamped on the 'stat.

Or just get a new one.

mike

i can get a new one for $10 so i'll just swap it and hope that works. thanks.

[asifallasleep]

I live in Southern Arizona, so I have a 71ºC thermostat. In the winter the mornings are around 32ºF +/- and, after driving for 5-6 min., I start to get heat. Except in 100º+ air temps my temp guage rarely gets much above the blue. After 10 min. of driving on cold mornings I get enough heat to get complaints from my wife about her feet cooking.

Maybe part of the problem lies with your heater core, but let's hope not. It's a little hard to change out - worse, if like me, you have A/C. As Steve J says above, check your heater valve to ensure it's working.

Bob Napier

the thermostat replacement is so cheap and easy i'll do that first and cross my fingers it's not the heating core. :-). thanks

[asifallasleep]

That's one thing- 2002 heaters usually work pretty well compared to other 40 year old cars.

Chect the Tstat.

After the car has warmed up, give the two heater hoses a feel to see if they are both warm. Possibly disconnect the heater hoses, connect a legnth of garden hose, and see if it flushes out any crap. Don't use hish pressure, you just want to see if there is any flow.

How is the heater valve working?

I'll try this today since I can't buy the part until monday. So if the hoses are warm i guess that would mean there is flow and that it must be the heater core? Hey Steve since you're in CA, which thermostat do you have? 80? 75? 71?

[kbmb02]

I'll be at the shop (North Orange County) on Monday with a temp sensor gun, which is a real accurate way to see what's going on with the thermostat and cooling system - we can arrange to have you drop by to check it out, email me if interested. -KB