No Heat - BMW Forum

gwee1966 · 02-19-2009, 04:47 PM

I just replaced the head gasket, profile gasket, thermostat, water pump and all the hoses in my '91 318is. The heat worked the first time I drove but now blows cold air. Any ideas?

johnnyBgood · 02-19-2009, 04:51 PM

Quote:

Originally Posted by gwee1966

I just replaced the head gasket, profile gasket, thermostat, water pump and all the hoses in my '91 318is. The heat worked the first time I drove but now blows cold air. Any ideas?

Is the engine running @ normal temp. or cooler than normal?

johnny,

gwee1966 · 02-19-2009, 05:54 PM

Hot!

johnnyBgood · 02-19-2009, 06:28 PM

Quote:

Originally Posted by gwee1966

Hot!

You probaly have air in the system and the system needs to be bled....although the e30 is suppose to self bleed, there is a bleed screw in the thermostat housing....run the engine to operating temp. & crack open that screw & squeeze the upper & lower radiator hoses, to push out any air pockets, top off coolant as needed....

p.s. if this does not do the trick.......maybe possible stuck closed t-stat, to check this.....the upper & lower radiator hoses should be pretty much the same temp. when you feel them @ operating temp.

k.sidlosky · 02-19-2009, 07:16 PM

I had to do that to mine when I first bought it, if that doesn't work look for the hoses that go intot he firewall they should be on the same side as the fuse box but diagonal to it and run some hose water through it, it usually works with chevys

silversled · 02-19-2009, 08:36 PM

I don't know what a profile gasket is...but it sounds as if you either need to bleed the cooling system or your heater control valve needs attention...they are closely related...good luck

gwee1966 · 02-19-2009, 08:39 PM

Thank you for your input. I already replaced the replacement(BavAuto) TStat w/ a factory one so I'm pretty sure thats not it. But I agree that the problem could be air trapped somewhere in the 2 million hoses on an M42!!! I have drained & refilled three different times during this project so I'll investigate your solutions before I go taking-off the whole mess again.

gwee1966 · 02-19-2009, 08:43 PM

What can you tell me about heater control valves silversled? Have you had probs w/ that?

BMWJNKY · 02-20-2009, 01:26 PM

I would stop draining and refilling the system, this is probably just going to get air back in the system. With the system filled and the heater temp control set to full hot let the car idle with out the radiator cap on it. It will take about 5min before the car will be warm enough to open the t-stat. Once the t-stat opens you should see the coolant level drop and air bubble up, keep filling the system until no more air comes out.

silversled · 02-20-2009, 08:52 PM

yeah, I've had to replace the heater control valve on my 1988 325ic. It's in the console on the drivers side. It's electrically controlled and, while not a total bitch to replace, it is somewhat of a task. But it sounds to me as if you need to bleed the cooling system. Open the bleed screw on the thermostat housing, as mentioned, with engine cold, then slightly tighten it and let the engine warm up slightly. After the engine starts to warm up loosen the bleed screw again and wait until pure coolant runs out. And I cannot emphasize this enough, HAVE THE HEATER CONTROL ON FULL HEAT SETTING' while performing this process, otherwise the heater control valve will keep the airlock right where it sits.... good luck

BMWJNKY · 02-21-2009, 07:24 PM

There is no bleeder screw on the t-stat housing on an M42.

johnnyBgood · 02-21-2009, 07:59 PM

Quote:

Originally Posted by BMWJNKY

There is no bleeder screw on the t-stat housing on an M42.

Then it should self bleed like you said......I just remember it being on my brother's 91' 325is......thought it might be on the 318i's too.

johnny,

silversled · 02-21-2009, 08:32 PM

well, OK, but that doesn't very advanced to me, having no bleed point available for a 1991 BMW engine. That almost seems backwards to me. There must be a bleed point somewhere. Heck, they had a bleed screw on my 1983 533i....gotta be somewhere to bleed the cooling system, but even so, if there are air pockets you still would still get heat occasionaly, it wouldn't lock like that. Sounds like something else to me then. Plus the temp gauge should jump with air pockets moving through the cooling system. Air heats up a lot quicker than coolant. That should be reflected on the coolant temp gauge on the dashboard, assuming you have one of those.

gwee1966 · 02-24-2009, 12:05 PM

It has to be air someplace. The heat has worked intermittantly. The bleed valve is right next to the expansion tank on M42.

marti5 · 02-24-2009, 01:42 PM

Sounds strange but try parking it up a hill/sloping drive nose up,then bleed the system, this does help, it does sound like air in the system.