M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: KenC on October 16, 2008, 01:57:40 PM
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I'm totally stumped on my cooling/heating system.
I have bled it about three times now, and I still can't get it to function properly.
Symptoms:
Heat only works while the car is moving and rpms above 2500. Blows cold air while idleing.
Any ideas?
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Thermostat in the right way? Check the coolant lines from the block to the firewall, do either of them get hot when the engine is hot?
Jack the front end up, bleed at a high idle. You do have the interior heater set all the way to hot and the interior fan on when you bleed it, right?
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What is the history ?
Has it always done this ?Did you do something recently?
Check you belt ? Make sure it's tight .
Might be the pump......
Might be the heater valve.....
Might need bleeding ............
Might be thermostat...........
Really need to know what led up to this to do a diagnosis ???
good luck
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I've bled it three times with the front end elevated every time. And yes, with the heater and blower both on high.
Although I haven't checked the heatercore lines for temperature, every time I've bled the system, the radiator return line has been warm so I'm assuming that coolant is flowing through all of the lines.
A cool output line would indicate a clogged heatercore?
How do I check the heater valve?
New thermostat and water pump didn't fix the issue. Pump is brand new, thermostat has about 5k on it.
Thermostat is in the right way (longer portion into the head) per Bentley manual.
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I've bled it three times with the front end elevated every time. And yes, with the heater and blower both on high.
Although I haven't checked the heatercore lines for temperature, every time I've bled the system, the radiator return line has been warm so I'm assuming that coolant is flowing through all of the lines.
A cool output line would indicate a clogged heatercore?
How do I check the heater valve?
New thermostat and water pump didn't fix the issue. Pump is brand new, thermostat has about 5k on it.
Thermostat is in the right way (longer portion into the head) per Bentley manual.
I had this problem but my fan was completely missing and it had similar symptoms. My guess is the valve.. its under the center console by the gas pedal. You have to pull the shifter console out to see it. You could cross wire it so hot coolant is always going through the heater core.. this is not so good during the summer
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I have that same issue. I just deal with it. Um. Thinking about it... Its been that way as long as i have owned the car. Since 97. I have replaced the thermostat twice and did a complete coolant changeover , like hoses and radiator.
Is... the long side of the thermo goes toward the cockpit right? Thats the way mine is.
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Would replacing the entire heatercore possibly fix this? Or would it just be easier to replace the valve? Is there one or two valves in the heatercore? I'd rather not just "deal with it."
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Would replacing the entire heatercore possibly fix this? Or would it just be easier to replace the valve? Is there one or two valves in the heatercore? I'd rather not just "deal with it."
lol he lives in florida not portland, the valve is an easy job.. entire heater core is not worth it unless you have a leak.
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Is there just the one valve? Or are there two?
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I believe there should be 1, at least from the bentley. If the valve is not working, not hot coolant will enter the heater core. Unlike the e28, if the valve is not working, it will not close and only hot coolant will enter heater core, which causes a premature leak.
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Check your radiator hoses to make sure they both get hot when engine is at operating temp.
Start your car cold and wait for the thermostat to open .When it does you should feel the hot water circulating around through the radiator hoses.They both should get hot.
good luck
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I believe your hoses should get hot no matter if your heater is working. Once engine gets hot, thermo opens, then allows coolant to enter radiator for extra cooling. If your heater valve is stuck close, you should not get heat. But you said you get heat when driving, this cold just be non-ac air entering cabin, which would seem warm. Currenlty on my car, I get no heat, but I dont care living in Miami. But when I fixed it in my m5, the heat was so hot I could not leave my hand in the way, almost burning heat. I remember taking the temp and it was over 120 degrees F.
Here is a pic of the coolant flow from the repair manual:
(http://ee1394.com/bmw/docs/factory/repair/en/repair/images/0328.jpg)
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Does the car run Hot ,What does your temp needle indicate?
Is the problem just no Heat coming out when you turn the heater on or does the car run hot or cold?
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Does the car run Hot ,What does your temp needle indicate?
Is the problem just no Heat coming out when you turn the heater on or does the car run hot or cold?
It doesn't get that hot. The needle will fluctuate a little below and a little above the center hash depending on the heater settings.
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It sounds like everything is working except that it is not flowing hot water through the heater core as it should. 3 causes for this:
Air bubble in the system preventing full flow.
Improperly functioning heater valve.
Clogged heater core.
Mercedes recommends a citric acid flush for their cooling systems. I just finished doing this on mine, and if there's crud in the core the flush procedure should clear it. It is pretty involved, and will kill an afternoon doing it, but it is effective. Info is on the MB mechanic board.
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I think I can rule out an air bubble as I've bled it three times on an incline.
Do you have a link to the MB article regarding the acid flush?
It sounds like everything is working except that it is not flowing hot water through the heater core as it should. 3 causes for this:
Air bubble in the system preventing full flow.
Improperly functioning heater valve.
Clogged heater core.
Mercedes recommends a citric acid flush for their cooling systems. I just finished doing this on mine, and if there's crud in the core the flush procedure should clear it. It is pretty involved, and will kill an afternoon doing it, but it is effective. Info is on the MB mechanic board.
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http://www.schumanautomotive.com/forums/showthread.php?t=264
Here's a good thread from the Schuman forum.
You can google it and find plenty of info.
I used Shout Gel for a degreaser.
e-bay might be your best source for the acid.
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Before you do the flush, make sure the valve is working. They do go bad. The bentley manaul, I think, has a procedure for testing it. You should hear a thump or click. Also on my e28, the temp selector knob was bad and would not give the correct voltage to the valve. You might have to look over the ETM to see how it works on the e30.
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I found this for you ..........
hope it helps
good luck
http://www.r3vlimited.com/board/showthread.php?t=98782
also
http://www.bavauto.com/assets/prodinfo_pages/e30heatercore.htm
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You know, the other thing that occurs to me is that recall that was done to add another valve between the block and the heater core, something to do with limiting pressure to the heater core so folks wouldn't have their legs scalded in the event of overpressurization of the cooling system... anyone remember the details of that, and do you have that valve in the path between the block and the firewall?
I also found a magazine article I saved from somewhere that shows how to rebuild the heater valve; unfortunately, I have no means of hosting the file, so if you would like it, send me a PM and I'll try to email it to you.
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I too have this problem in my e36.... but no heat at any rpm's and engine temp runs fine.
where do i start?
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Is the heater valve a separate part from the inlet pipe? Realoem makes it look like one.
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Is the heater valve a separate part from the inlet pipe? Realoem makes it look like one.
anyone?
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I believe it is. Wil be in between heater core and inlet pipes coming from engine bay. I haven't done this work so not sure. I know there is a link on a DIY listed above.
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Mine had the opposite symptoms until I corrected the issue last night. The heater hoses at the firewall were reversed. I only got heat at idle and cold air while driving.
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I'm still stumped. I replaced the heater core and heater valve last night, and I'm still having the same issue.
I only get heat while the rpms are above 2500. It doesn not matter whether the car is moving or not.
My coolant temp rises at idle, but will maintain a normal temp when the rpms are above 2500. It doesn't make a difference if the car is moving vs stationary.
Any ideas? Could a bad fan-clutch cause the issues with the heater output?
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I'm still stumped. I replaced the heater core and heater valve last night, and I'm still having the same issue.
I only get heat while the rpms are above 2500. It doesn not matter whether the car is moving or not.
My coolant temp rises at idle, but will maintain a normal temp when the rpms are above 2500. It doesn't make a difference if the car is moving vs stationary.
Any ideas? Could a bad fan-clutch cause the issues with the heater output?
Can you hear the fan kicking on? For some reason someone pulled out my blower fan so i would only get heat when i revved the car or was moving fairly fast. Its really easy to get too.. Gotta move the wiring and there is a little door in the firewall to get to it. It has a resistor that could be bad or broken and would cause your heat to not work.
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coolant pump?
coolant is made to transfer heat, it could be moving heat through from the engine to hoses enough to make you think its really moving liquid, but is there really the pressure there should be?
not sure, just wondering....
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Can you hear the fan kicking on? For some reason someone pulled out my blower fan so i would only get heat when i revved the car or was moving fairly fast. Its really easy to get too.. Gotta move the wiring and there is a little door in the firewall to get to it. It has a resistor that could be bad or broken and would cause your heat to not work.
Blower motor has been replaced and works great.
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coolant pump?
coolant is made to transfer heat, it could be moving heat through from the engine to hoses enough to make you think its really moving liquid, but is there really the pressure there should be?
not sure, just wondering....
Como?
Water pump is brand new.
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water pump is new?
But are you sure its working correctly?
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If the engine at idle does not stay around Half mark(temp gauge) but will stay at Half mark when traveling or higher rpms , I believe that would indicate a problem with the Thermostat. I know you say it's practically new but you've replaced everything but that so far.
good luck
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I replaced my stat about a year ago and it was defective, doing exactly that. They popped another one in and it was good.
With the price of them, it might be worth snagging a spare :confused:
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If the engine at idle does not stay around Half mark(temp gauge) but will stay at Half mark when traveling or higher rpms , I believe that would indicate a problem with the Thermostat. I know you say it's practically new but you've replaced everything but that so far.
good luck
That's what I was thinking... esp after the drive I just took. The temperature fluxuated WAY too much for the thermostat to be functioning properly.
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Sorry to bump a week or two old thread, but I'm currently dealing with the same issue.
I had no heat at all and the temp needle wasnt leaving the blue, so I went in after the thermostat. After replacing the thermostat the engine temperature comes up to mid-way and fluctuates. Appears to be better, but not perfect. I have heat when revving the car above 2500 rpm, but not at idle.
I'm wondering if the heater core bypass that was added in could be the culprit.. I'll go after that next.
Havent had any time to look deeper into it.
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If a heater core by pass was done you wouldn't have any heat???
Make sure you bleed all the air out of the system ,Then bleed it again.
good luck
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The heater valve is a separate pipe connected to the heater core.
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If a heater core by pass was done you wouldn't have any heat???
Not sure why I said by-pass. I believe it's the pressure relief valve that was added in at the dealer to keep the heater core from bursting and covering the driver's feet.
I dont see how it could be an air bubble. I have never had a problem bleeding a BMW cooling system. But either way I'll be going into it again to see what the issue is.
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Mine had the opposite symptoms until I corrected the issue last night. The heater hoses at the firewall were reversed. I only got heat at idle and cold air while driving.
This is worth checking... I did this by mistake with my m50 swap a couple years ago and had temp flux issues and no heat unless I mashed on it and then the core exploded to boot!