Why can I hear coolant behind my dash?

[killian665]

This has been going on since I’ve owned the car. I can hear swishing noises, which I assume is coolant passing through the heater core, behind the dash. Usually more audible when I accelerate from. a stop. I imagine this means I have air in the system but I don’t over heat and the expansion tank is at the proper level.

Is there a special process to bleed these cars with the electric pump similar to the E9x cars or should I just keep trying the old fashioned way?

[8eights]

Raise the front of the car or drive it to a incline and bleed from the reservoir, there is a phillips plastic bleed screw there. Let warm up bleed and repeat till all bubbles are out.

[ChrisFuture8]

This has been going on since I’ve owned the car. I can hear swishing noises, which I assume is coolant passing through the heater core, behind the dash. Usually more audible when I accelerate from. a stop. I imagine this means I have air in the system but I don’t over heat and the expansion tank is at the proper level.

Is there a special process to bleed these cars with the electric pump similar to the E9x cars or should I just keep trying the old fashioned way?

I have the exact same issue for a couple years now. I think the heater core has a small leak. There was at one point my windshield fogged up slightly at the base of the windshield during warm weather. That's what made me suspect the heater core in my car has a minor leak. It's a very slow and small leak but enough to create air bubbles in the cooling system. A bit annoying and worrisome at the same time. I don't know if i have the stomach to pull the dash yet. Done veterans on here have. Welcome to the world of perpetual project exotic 8.

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[ChrisFuture8]

Raise the front of the car or drive it to a incline and bleed from the reservoir, there is a phillips plastic bleed screw there. Let warm up bleed and repeat till all bubbles are out.

At Killian. When coolant is hot, don't over tighten the expansion tank bleed screw or you'll be replacing the expansion tank soon. Don't ask...lol.

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[Carl1011]

Timm has a troubleshooting guide for bleeding. I suggest you do his 4000 rpm procedure. It worked for me. The heater valves are located above the engine therefore air accumulates there instead of the radiator. Hence the need to raise the front of the car. Make sure you run the engine at 4000 rpm to get the aux pump to circulate the coolant.
http://www.meeknet.co.uk/e31/E31_Hea...eplacement.htm

[killian665]

Worked, thanks guys.