Author Topic: no heat car running hot (Read 5155 times)

318lotis · « **on:** October 21, 2009, 06:31:52 PM »

hey gang, my e30 m42 318is over heated today , i turned on the heater and it blew cold air. any suggestions ? thanx 318lotis

DesktopDave · « **Reply #1 on:** October 21, 2009, 08:02:23 PM »

Did you change the coolant recently? Just wondering, these cars are difficult to purge air from.

How long did it overheat? Did it run into the red zone? Do quick checks for oil in the coolant or frothy milkshake oil.

318lotis · « **Reply #2 on:** October 21, 2009, 08:15:54 PM »

thanx, no i havnt changed coolant recently, no, it did not red zone, we think fan clutch is bad causing the over heating, but why would the heater stop generating hot air? could it be the water pump is shot as well?
thanx, 318lotis

monty23psk · « **Reply #3 on:** October 21, 2009, 09:05:28 PM »

If there is no heat in the car at any time, then you are not getting hot coolan into the heater core or the valve is bad, which would stay closed. When you move the temp to hot, you should hear a small thump by the gas pedal, that is the heater valve. I would first check the overheating issue before going after the heater issue.

318lotis · « **Reply #4 on:** October 21, 2009, 09:21:12 PM »

thanx for imput gang

DesktopDave · « **Reply #5 on:** October 22, 2009, 10:49:40 AM »

Quote from: 318lotis;80233

thanx, no i havnt changed coolant recently, no, it did not red zone, we think fan clutch is bad causing the over heating, but why would the heater stop generating hot air? could it be the water pump is shot as well?
thanx, 318lotis

IMHO a bad fan clutch shouldn't cause your symptoms. Low coolant/plugged radiator/bad pump/coolant leaks or a bad heater core valve will. Maybe try running it (keep your eyes on the gauge) to see if you can spot any leaks. Hopefully it's just a leaking hose...that'd be my first guess. Some leaks evaporate before you can see where they're coming from.

A cheap test for the fan clutch is the newspaper test...when it's hot it should easily shred a rolled up newspaper. Or shut the engine down hot and spin the fan. It should have pretty strong resistance when hot but spin easily when cold.

Maybe check the aux fan too. Pull the wiring connector off the radiator & jump the wires to see if the aux fan turns on both low and high speeds.

cleaner32 · « **Reply #6 on:** October 22, 2009, 12:44:34 PM »

Its low on coolant

spalets · « **Reply #7 on:** November 10, 2009, 07:45:36 PM »

Hey I had a similar problem.

I had been hearing this annoying clicking sound by the gas pedal, like a faint thump. I had my mechanic and BMW look at it and they couldn't figure out what it would be. It only did it when the engine was hot, so it looks like that might have been a dysfunctional or jamming heater valve. Any other ideas? It just stopped making that noise about 3 days ago, right before my engine overheated.

I've also noticed the fan doesn't come on properly and suspect it is the mechanical fan clutch.

Yesterday my engine overheats and after red zoning, the heater stopped working. I filled the coolant up because it was virtually empty and took it for a drive today. After a couple minutes of driving it, it went up quickly to the regular temperature level, and stayed level until I got home. It stayed level at idle, but still after all of this, no heat from the vents.

Can anyone advise me as to what they think the issue is?

I'm going to bring it in to BMW soon, but they are booked till next week.

Is this safe to drive?

spalets · « **Reply #8 on:** November 10, 2009, 07:59:21 PM »

LeeThompson · « **Reply #9 on:** November 10, 2009, 08:44:10 PM »

Had a similar problem today. Hot air just stopped working and the temp gage shot up. Took it to the shop and the fan belt was missing. Make sure that is still there.

DesktopDave · « **Reply #10 on:** November 11, 2009, 08:12:08 AM »

Stop driving that car until you find where the coolant is going. You'll pop a head gasket or warp the head.

If you're not getting heat the system might need bled out properly. This car is notorious for air-locked water pumps. Also be very careful with the rad bleeder screw. Don't use a philips screwdriver, just a big flat-blade and tighten it only until coolant stops flowing. It'll crack otherwise & you'll have a ten-foot geyser of 200degF coolant. Don't ask me how I know, I had to walk two miles back home. Damn Behr.

Did you test the coolant temp thermo switch on the passenger side of the radiator? If that's bad the aux fan will never turn on, unless you're using the A/C. Pull the connector & jump it with a bit of wire to see if the fan spins.

You should be able to turn the engine-driven fan easily when it's cold but it'll have much more resistance when it's hot. You can also test it with the engine running by using a magazine or rolled newspaper. It should be strong enough to shred the paper when it's hot. Keep your fingers away, of course.

spalets · « **Reply #11 on:** November 12, 2009, 07:21:30 PM »

Quote from: DesktopDave;81274

Stop driving that car until you find where the coolant is going. You'll pop a head gasket or warp the head.

If you're not getting heat the system might need bled out properly. This car is notorious for air-locked water pumps. Also be very careful with the rad bleeder screw. Don't use a philips screwdriver, just a big flat-blade and tighten it only until coolant stops flowing. It'll crack otherwise & you'll have a ten-foot geyser of 200degF coolant. Don't ask me how I know, I had to walk two miles back home. Damn Behr.

Did you test the coolant temp thermo switch on the passenger side of the radiator? If that's bad the aux fan will never turn on, unless you're using the A/C. Pull the connector & jump it with a bit of wire to see if the fan spins.

You should be able to turn the engine-driven fan easily when it's cold but it'll have much more resistance when it's hot. You can also test it with the engine running by using a magazine or rolled newspaper. It should be strong enough to shred the paper when it's hot. Keep your fingers away, of course.

Yeah, thanks man.

The coolant flange was cracked and leaking. The weird part is, before it overheated, it hadn't leaked at all, but the mechanical fan appears to work fine.

In any case, I got the flange replaced and now all is good.

Aux fan works fine, or at least it did the last time I used A/C (which was a long time ago, I live in Canada).

Heat was restored after fixing the leak and bleeding the system.

The faint thump is still there and I'm almost sure it's the heater valve, as I checked again and it doesn't make the sound when the heat is off. Also, it only makes the sound when the engine is hot.

Thanks for your help!

DesktopDave · « **Reply #12 on:** November 12, 2009, 07:53:03 PM »

Cool. Glad it's fixed...the coolant system is weak on these cars and it seems that a single overheat will pop a gasket or warp a head.