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heater valve e30

3K views 7 replies 4 participants last post by  cseibt 
#1 ·
I'm new to this site. so if this was already covered please direct me to the thread. We just replaced the heater valve in our 86 325. Lots of heat for a few miles then the valve makes a flapping noise and the heat goes away. Shut off the car and restart it and there is heat again and the cycle continues. The mechanic bled it and I have bled it but maybe there is still air trapped?? No overheating of the engine.
thanx
 
#5 ·
Rick; I have discovered that the problem is somehow related to road speed. In town the heater works fine at say 2,000 rpm. at 60 mph (2,000 rpm) on the road the ticking/flapping noise occurs and the heat goes away? Engine temperature stays constant. Is there a cold air diverter ot flap that might be allowing cold air to overpower the heater?
dave
 
#8 ·
I have a 92 325ic with the exact same problem - no heat at high speed, and thumping noise (almost sounds like a rod knock) at low speed/mild acceleration. The problem? the heater hoses were backward by the previous owner. I knew the knock was heat related because I could stop it instantly by turning the climate control to full cold.

Tried a new t-stat with no love, then started feeling around under dash and traced the knock to the bottom heater hose. Swapped the inlet and outlet hoses, and the noise went away, the heat works at all speeds, and you can now fry an egg on the vents it is so nice and toasty!
 
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