Help, Cooling system overhaul problem, heater not blowing hot air, engine shut off.

[lorensiuswlt]

Hello fellows,

I just replaced my waterpump, thermostat & it's housing, upper & lower radiator hose. Before that my waterpump broken so i did that overhaul and flush all the coolant. After refilling the coolant, there were little air bubles and coolant comming out from the bleed screw.So i started the engine, did some revs @200rpm then some air bubles came out from the bleed screw but the upper radiator hose seemed to not have pressure but it was hot. And also the heater did not blow hot air. The temp gauge was normal, it stopped at the middle and pointing up. The engine also shut off itself and i had to wait several minutes to start it again.

I tried to jack up the car and topped up some coolants and bleed but after running for about ten mintues, the engine shut off itself and the heater still blow cold air.

How to overcome these problems?

Thank you..

[UsernaM3]

Shogun and others have some good advice in this thread. Worth checking out: https://www.bimmerforums.com/forum/s...emp-solved-CPS

Edit: the heater not blowing hot indicates you still have air in the system. Continue bleeding. But I don’t have any advice for the shutoff issue unfortunately.

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[lorensiuswlt]

Shogun and others have some good advice in this thread. Worth checking out: https://www.bimmerforums.com/forum/s...emp-solved-CPS

Edit: the heater not blowing hot indicates you still have air in the system. Continue bleeding. But I don’t have any advice for the shutoff issue unfortunately.

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Hi UsernaM3, thanks for the link..it really helps..
Seems that i have bad crankshaft position sensor (cps). Tested the resistance of the sensor but the value was too small from the spec. I'll try to replace the cps and tried to bleed the cooling system again..thank you very much.

[UsernaM3]

Hi UsernaM3, thanks for the link..it really helps..
Seems that i have bad crankshaft position sensor (cps). Tested the resistance of the sensor but the value was too small from the spec. I'll try to replace the cps and tried to bleed the cooling system again..thank you very much.

Nice (finding a solution, sucks it’s bad lol)! Let us know how it goes.


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[lorensiuswlt]

Nice (finding a solution, sucks it’s bad lol)! Let us know how it goes.


Sent from my iPhone using Tapatalk

Hi UsernaM3,

I've replaced the bad crankshaft position sensor, the engine shut off proble solved. I've tried flush and refill the coolant, bleed until no air bubble coming out from the bleed screw but still now hot air from the vents.

Thank you

[importbanana]

you need to turn on the heater to max temp, lowest fan setting, and while bleeding rev the warm engine to 4-5k rpm. high flow is needed to flush the air out. had the same dozen times before

[UsernaM3]

Hi UsernaM3,

I've replaced the bad crankshaft position sensor, the engine shut off proble solved. I've tried flush and refill the coolant, bleed until no air bubble coming out from the bleed screw but still now hot air from the vents.

Thank you

Glad to hear that fixed the issue!

Just like the poster above me said.

I followed the Bentley manual for the initial fill.

1) turn key to on position (without starting vehicle)
2) turn air to max temp and Max air pressure
3) open bleed screw and begin filling. Keep filling until the reservoir won’t take any more coolant
4) burp the upper and lower hoses while doing this (just give them a good squeeze)


After that, I did the following (I have a ramp into my garage so I parked half the car in the garage and half outside. You can also use ramps or just jack the car up in the front):

1) unscrew reservoir cap or leave It on very, very loose (this is to keep the system from over pressurizing).
2) start engine (again max fan and heat) and allow the car to warm up to temp. 2a)Keep an eye on the reservoir and fill as needed. Periodically releasing the bleed screw.
3) once at temp, hop in the car and rev the motor to about 2.5-3k RPMs and keep it there for about 5 seconds. Let off the gas and do that again.
4) get out, go to the bleed screw and release the bleed screw which will allow air to come out. Tighten the screw and repeat step 3 and fill coolant as necessary.
5) over time the coolant can get hot enough to expand and start to flow out of the reservoir. If this happens, shut the car off and let it cool until the level is down to a reasonable level.

Other things to note: I also would stand at the front of the car and rev the motor just by opening the throttle body. What I noticed was that I could see a stream of coolant in the top of the reservoir which leads from the upper return hose. When you rev the motor and you don’t have bubbles in that stream, you’re basically bled.

Another thing I’d do is occasionally burp the upper and lower radiator hoses. Not sure if it helped, but it can’t hurt.


Keep coolant in your car for the next couple days. And be sure to check the level before each drive.

Hopefully that helps! Bleeding these without a vacuum fill tool can be a pain. Be patient and keep an eye on the temp gauge. If you start to feel uneasy or that the car has been on a long time, there’s nothing wrong with shutting her down and letting it cool to start over later.

[importbanana]

2) max air is unnecessary

only max temp is important


2.5k or 3k rpm might not be enough, don't hesitate to rev higher when it's warm, i guarantee you 2k rpm is not enough, 5k will get that air out of there. spent hours before like you did to find out why heat doesn't work and then it suddenly all worked after higher revs. it needs the high flow to flush the air out of there.

people keep saying e36 are hard to bleed. one just needs to do it properly.

[lorensiuswlt]

Hi UsernaM3 & importbanan,

Sorry for the late replay and thank you very much for the suggestions. I've driven the car since last bleeding, the vent still blowing cold air and the engine temp needle still pointing up (no overheat). Yesterday i tried to bleed again as your suggestions, but still no hot air. When bleeding, i saw bubbles coming out from the screw. I did some rev by opening the throttle body, i guess it was 2.5-4k rpm. I'll try to bleed again next morning. If it doesn't work, could it be caused by clogged heater valve? because my previous water pump impeller was broken into pieces inside.

Glad to hear that fixed the issue!

Just like the poster above me said.

I followed the Bentley manual for the initial fill.

1) turn key to on position (without starting vehicle)
2) turn air to max temp and Max air pressure
3) open bleed screw and begin filling. Keep filling until the reservoir won’t take any more coolant
4) burp the upper and lower hoses while doing this (just give them a good squeeze)


After that, I did the following (I have a ramp into my garage so I parked half the car in the garage and half outside. You can also use ramps or just jack the car up in the front):

1) unscrew reservoir cap or leave It on very, very loose (this is to keep the system from over pressurizing).
2) start engine (again max fan and heat) and allow the car to warm up to temp. 2a)Keep an eye on the reservoir and fill as needed. Periodically releasing the bleed screw.
3) once at temp, hop in the car and rev the motor to about 2.5-3k RPMs and keep it there for about 5 seconds. Let off the gas and do that again.
4) get out, go to the bleed screw and release the bleed screw which will allow air to come out. Tighten the screw and repeat step 3 and fill coolant as necessary.
5) over time the coolant can get hot enough to expand and start to flow out of the reservoir. If this happens, shut the car off and let it cool until the level is down to a reasonable level.

Other things to note: I also would stand at the front of the car and rev the motor just by opening the throttle body. What I noticed was that I could see a stream of coolant in the top of the reservoir which leads from the upper return hose. When you rev the motor and you don’t have bubbles in that stream, you’re basically bled.

Another thing I’d do is occasionally burp the upper and lower radiator hoses. Not sure if it helped, but it can’t hurt.


Keep coolant in your car for the next couple days. And be sure to check the level before each drive.

Hopefully that helps! Bleeding these without a vacuum fill tool can be a pain. Be patient and keep an eye on the temp gauge. If you start to feel uneasy or that the car has been on a long time, there’s nothing wrong with shutting her down and letting it cool to start over later.

you need to turn on the heater to max temp, lowest fan setting, and while bleeding rev the warm engine to 4-5k rpm. high flow is needed to flush the air out. had the same dozen times before

2) max air is unnecessary

only max temp is important


2.5k or 3k rpm might not be enough, don't hesitate to rev higher when it's warm, i guarantee you 2k rpm is not enough, 5k will get that air out of there. spent hours before like you did to find out why heat doesn't work and then it suddenly all worked after higher revs. it needs the high flow to flush the air out of there.

people keep saying e36 are hard to bleed. one just needs to do it properly.

[Eric93se]

Its possible the heater valve is bad that does happen but the fact that the old WP blew up means there's a good chance the head is cracked and that's why you see some bubbles when you do some bleeding. I would say next step is to get a test kit to see if there's exhaust gasses in the coolant. If its positive you can then do a compression test.

[lorensiuswlt]

Its possible the heater valve is bad that does happen but the fact that the old WP blew up means there's a good chance the head is cracked and that's why you see some bubbles when you do some bleeding. I would say next step is to get a test kit to see if there's exhaust gasses in the coolant. If its positive you can then do a compression test.

Hi Eric93se,

Thanks for the info, i'll try that . So far the car working great, except for the heater. I'm rarely use that so that's not a big problem but it is still on my diy to do list ).

Regards.

[importbanana]

I tell you again you didn't rev high and long enough to flow the air out there, while the heater temp was set to max. You've no idea how high you revved as you didn't look at the dash but did it by moving the throttle body in the engine bay.

Not saying it's that, but it doesn't cost anything and therefore you should try that first.

[lorensiuswlt]

I tell you again you didn't rev high and long enough to flow the air out there, while the heater temp was set to max. You've no idea how high you revved as you didn't look at the dash but did it by moving the throttle body in the engine bay.

Not saying it's that, but it doesn't cost anything and therefore you should try that first.

Thanks importbanana, i'll try that, definitely on my to do list.

Regards