Phantom Heat Anxiety Syndrome

[eastsidebimmer]

I drove my 68 last night for the first time since November to our local CCA meeting and I had a weird heat problem again:

Running well, temp gauge right in the middle, great heat all the way there (20 miles).

On the way home, without touching anything--I had great heat for about 10 minutes, then no heat for about 5 minutes and then full heat again as I got closer to home.

Ideas?

Thanks!

[Paul7002]

Are you running the fan? or just letting the air flow through as you go down the road?

If there is no air sitting still, the fan's not working. If there is no air going down the road with the fan off (try it with fan off) there is something blocking air flow - Leaves, mouse nest, dead squirrel, etc.

If you have air but it's cold, I suspect blockage in the heater valve or perhaps even in the core itself.

[Rob7502]

Sounds like you have an air gap in the system

[Paul7002]

I hadn't thought of that.

[eastsidebimmer]

I do get good heat and the 2 speed fan works on both speeds.

The problem is an abrupt loss of heat for only a short period of time.

It actually was blowing cold unheated air for about 5 minutes, then warm again without touching anything.

I did have the coolant system flushed by a reputable independent BMW facility last fall. I also think the temp gauge runs hotter sometimes than it ever did before (just above middle). Perhaps I do have a bubble. I took ownership in September 05, so I don't have anything to compare it to.

How shall I effectively "burp" the system?

[Mike Self]

were eventually traced to a sticky 'stat...

[c.d.iesel]

YOUR low on coolent

and you have an air pocket in the cooling system

and the thermostat is in that intermittant air pocket

and your going to warp yer cylinder

head if

you keep driving it this

way.

Pressure test the

cooling system for leaks - test with the motor

cold and hot.

How old is the thermostat ?

how long have you owned the car?

any motor history you want to share?

[eastsidebimmer]

Thanks for the tips--I'll be sure to have it flatbedded back to the shop for the burpjob.