Author Topic: Need help quick! 92 318is - Suddenly No Heat but not overheating? (Read 3792 times)

dr_erni · « **on:** December 14, 2009, 05:59:01 PM »

Heat blew fine all day, but just from the last stop to home it stopped blowing heat. Fan works fine and the engine temp is fine, but when I crank up the heat and far it just blows cold.

Now, its very cold here these days and we did drive down a bumpy road so I wanted to ask you guys for which areas to check before I go out there in the cold to give it a shot??

Thanks in advance!

Boosted E30 · « **Reply #1 on:** December 14, 2009, 08:32:55 PM »

+1 on the cold in calgary its freezing here!!!!

Check to see if both radiator hoses are hot if the lower one is cold or colder then the upper your thermostate could be stuck.

Or you might not have any flow through the heater core if you can reach the hoses coming in and out of the fire wall make sure those are hot as well.

if all the hoses are hot then your heater valve #1 in the pic is the problem as it has 2 rubber diaphrams inside and they will deteriorate over time and once they brake you have poor heat or none at all.

http://www.realoem.com/bmw/showparts.do?model=BE53&mospid=47480&btnr=64_0126&hg=64&fg=18

if your not comfortable fixing it or dont know how i have a shop in calgary and we specialize in bmw's pm me if you want details.

dr_erni · « **Reply #2 on:** December 14, 2009, 08:44:52 PM »

I'll have a look tomorrow, but after scrounging up some courage to face the cold, I went back out and checked the coolant level [which is what I should have done in the first place... doh]. It was lower then it should be so I added some more mix and it seemed a blow warmer.

I'll give it a better test run tomorrow and update at the end of the day.

dr_erni · « **Reply #3 on:** December 17, 2009, 04:54:18 PM »

UPDATE: Added the missing coolant, the heat coming out is now warm-ish, but still not hot. Car is still not overheating. I'll check the hose temp next time I'm in town, but last time the top hose was warm (didn't check the lower one)

Will report back when I check it next. Thanks for the help!

quinn11m20 · « **Reply #4 on:** December 17, 2009, 06:33:29 PM »

Hoses are warm, could be your thermostat is stuck open. The coolant will continue to flow but not heat up the engine. I have had this happen before. I thank my stars that is was stuck open and not closed. I live in Florida, so the temp usually stays near the 80 deg mark all year round.

So like Boosted posted, could also be the heater valve. Sounds like you are troubleshooting in the right direction. Good luck and stay warm.

bih55 · « **Reply #5 on:** December 19, 2009, 11:20:21 PM »

also make sure u used 50/50 mix of antifreeze. I had more water and when it got cold the coolant was frozen and no heat. also when the engine is running take off the cap and see if the coolant is flowing with increased acc

dr_erni · « **Reply #6 on:** January 06, 2010, 09:02:34 PM »

All right... so back in Calgary now and drove to car today. With re-circulate on, the heat is tolerable but definitely not hot. Hoses are hot and engine stays at a good operating temperature. Another thing i noticed is icing on inside windows in the car. I guess that could be due to the door design? Anyone else have this happen?

Once we get to some plus temps I'll have time to have a decent look at the heater and such... but I'd like to ask for your opinion:

- How difficult is it to change the heater valve?
- Is there a quick way to test the it first? (aside from lack of heat in the car har har)
- Do I need to bleed the coolant before doing the swap?
- Should I consider changing the core instead? How difficult is that swap?
- Should I look for used parts or go new right away?

DesktopDave · « **Reply #7 on:** January 07, 2010, 06:35:29 AM »

I've never changed one in the e36, but they're usually straightforward.

You could splice a pipe in place of the valve to test it, but I'd see if it was working while the coolant was draining. Plug it in, turn the heater valve and see if it's moving at all. The ETM might have some info too.

Don't worry about bleeding the coolant before the swap. Bleed the heck out of it later.

The core is OK if you don't smell coolant inside the cabin.

I'd consider used parts if I could confirm that they work. This part does seem to have a definite lifespan, so it's a gamble. They won't take parts back either. If you go to a pick-n-pull you can even practice the job first, before doing it to your car.