Author Topic: Heating/engine cooling problems (Read 5382 times)

91 318is · « **on:** September 28, 2009, 06:27:16 AM »

I know, this is like the 243423412 thread about this problem, but after searching for a little bit, I couldn't find a solid answer for my problem.

Anywho, here's my dilemma. I'm having problems with the heat in the car working, when I'm idling, the engine temp seems to slowly heat, as soon as I starting moving, the temp drops, but if I turn the heat off and slide the temp control all the way to cold, it warms back up.

I've tried to bleed the coolant to see if it's air, didn't get anything. I checked the heater hoses a while back and I'm pretty sure they were in the right position. I didn't actually swap them, but I can. The previous owner said he installed a new thermostat in the car, but I may swap it out anyways to eliminate that off the list.

Also, it might the be heater valve too? I read your suppose to hear a click from it, went out yesterday, started it up and tried it, never heard a click. When are you suppose to hear it?

Starting to get cold out, so I gotta fix it now.

doitover · « **Reply #1 on:** September 28, 2009, 09:52:58 AM »

If it is running too cool I'd try the thermostat.

monty23psk · « **Reply #2 on:** September 28, 2009, 10:34:36 AM »

If the the temp creeps up at idle normally it is the fan clutch. Also if you have the heater on, it helps cooling the engine. If you have it off, the coolant takes a shorter passage and doesnt cool off as fast.

Do you have the AC on? If so the aux fan should come on, is it? Also the aux fan should turn on at low at 91 degrees Celsius.

RED IS 91 · « **Reply #3 on:** September 28, 2009, 11:12:23 AM »

Sounds like your thermostat is stuck open . The hoses that go to your heater core should be hot but if the motor doesn't reach operating temperature it won't matter.

Does the motor reach operating temp. ? That's the first question.

iamcreepingdeath · « **Reply #4 on:** September 28, 2009, 10:01:38 PM »

I went through a huge cooling system overhaul on my E30, and my thread on it is here: http://www.m42club.com/forums/showthread.php?t=9603

So i am the cooling system guru by now, or i had better be.

So anyway we need more info. To what position does the temp gauge go? when at an idle and no heat on, does the temp gauge rise indefinitely? When driving with the heat on, where does the temp gage drop to?

I would immediately test your fan clutch. At an idle, see if you can shove a rolled up magazine into the spinning fan. If the fan is stopped easily by the magazine, get a new fan clutch. If you get confetti, as another member here put it, then the fan clutch is good.

91 318is · « **Reply #5 on:** September 29, 2009, 06:20:01 AM »

Sorry for the late reply, checked my heater hoses again yesterday to confirm, and they're right.

Quote from: monty23psk;79044

Do you have the AC on? If so the aux fan should come on, is it? Also the aux fan should turn on at low at 91 degrees Celsius.

Haven't checked that, I will today.

Quote from: RED IS 91;79070

Does the motor reach operating temp. ? That's the first question.

Yes, read below what I wrote and that will explain it a little better.

When I bought the car, the owner said the radiator, water pump, thermostat, and clutch fan were replaced. I can obviously tell that the fan and radiator are pretty new, but I'll check the fan today.

I was messing with the car on the way to work yesterday trying to figure it out. In the morning, it was in the mid 60's, the car took a little while to warm, probably about 10-15 minutes of driving, this is with the heat completely off. As soon as I turn the heat on, the temp dropped from the middle mark to almost the 1/4 mark. I turned the heat back off completely. On the way home, temp was about 80. I let the car get to full operating temp (was quicker this time), got on the highway, turned the heat on, and the temp dropped a tad, nowhere near as much as it did in the morning.

I'm beginning to think it's either the thermostat or the heater valve. What is the purpose of the heater valve? Is it control the amount of the coolant through the heater core to keep the engine at operating temp?

The car seems to take longer to warm up, and have heater problems the colder it is outside. Once winter hits, it will probably get worse.

I even tried the heater a few times in the dead heat of summer, just to see what it would do, and it didn't fail at all.

Hope that helps

doitover · « **Reply #6 on:** September 29, 2009, 10:12:29 AM »

It sounds like the thermostat. All that you are doing when you turn the heater on is to effectively make the radiator bigger so you would expect that to drop the engine temperature if the thermostat is stuck open.

monty23psk · « **Reply #7 on:** September 29, 2009, 10:17:04 AM »

the heater valve will just allow or block water into the heater core and back out to the engine. Then with the blower on, it will blow air thru the core which is hot and then hot air comes out of the vents. Magic.

iamcreepingdeath · « **Reply #8 on:** September 29, 2009, 11:21:56 AM »

i'd say try a new t-stat. By turning on the heat, the temp will drop a little, i have never heard of the needle dropping an entire 1/4, but if the t-stat is working, it should close and allow the engine to heat up again to the operating temp after the heat is turned on. If the engine continues to run cold after the heat is turned on, then the t-stat is stuck open.

RED IS 91 · « **Reply #9 on:** September 29, 2009, 11:38:12 AM »

91 318is · « **Reply #10 on:** September 29, 2009, 09:26:12 PM »

Yeah I'm thinking the T-stat also, I'll swap it out and see what happens.

About the heater valve, is it suppose to click when it's activated right? When should it click? When I turn the fan on?

monty23psk · « **Reply #11 on:** September 29, 2009, 09:59:26 PM »

It should click as you move the temp knob to hot. Not sure where exactly, but at least past 12 o'clock.

91 318is · « **Reply #12 on:** September 29, 2009, 10:23:38 PM »

Quote from: monty23psk;79194

It should click as you move the temp knob to hot. Not sure where exactly, but at least past 12 o'clock.

I will check it again tomorrow, I was messing with it this morning, slowly moving the temp control, never heard a click though.

monty23psk · « **Reply #13 on:** September 30, 2009, 09:36:25 AM »

Mine valve is dead. I get not noise. But since I live where I never need the heat, I just dont worry about it. I will get to it as I do not want the heater core to go bad.

91 318is · « **Reply #14 on:** October 01, 2009, 06:02:26 AM »

Does the car have to be at full operating temp to check the valve? I know it seems like a dumb question, but I'm curious cause I checked mine right when I started it up in the morning.