1991 735il heating problem

[tommyc10]

I just turned the heating system in my car and nothing but cool air comes out. Normally this car would heat up in an instant. The blower is working fine. Any suggestions. Is this a big repair if necessary. I checked all fuses and they appear fine too. Thanks

[redhed]

This is most likely your heater core. Check that and also check the hoses that lead into it. One of the hoses may be badly clogged.

[libertylover]

If it's the heater core it's a huge labor-intensive repair which requires you to remove the console and a large portion of the dashboard. I haven't done it but I've read that it's not hard, just takes a lot of time since there is so much stuff to remove. This is something you only want to do after you've checked everything else.

My impression though was that a heater core failure usually leaks into the passenger compartment and the first thing you notice is the smell of hot coolant.

The best site that I know of for heating issues is here (look under IHKA):
http://bmwe32.student.utwente.nl/

[tommyc10]

I appreciate all responses to my issue - thanks!! After not having heat for 2 days it all of the sudden began to work again last night. Could there have been some type of vapor lock that may have prevented the heat from getting into the car. I did notice the thermostat was running a little to the right of center while the heat was not working. As I was running the car last night the heat came back on in full force and the thermostat went back to the normal center position. Anyone have this happen to them??

[libertylover]

It does indeed sound like you had air trapped in the system if it started working again. Here's the procedure to bleed the air from an M30 engine:

-Add coolant to expansion tank until level reaches COLD mark on the tank.

- Loosen bleeder screw on thermostat housing.

- Add coolant to expansion tank until it spills from the screw. Tighten screw.

There's more at the following link with pictures as well. http://www.nmia.com/~dgnrg/page_19.htm

[tommyc10]

Thank you very much for the info!!

[redhed]

After reading your latest post, might I suggest that you have your thermostat looked and and maybe replaced? When your thermostat sticks "closed", it prevents warm air from circulating properly and will cause your engine to "run hot". They usually are relatively inexpensive to have replaced.