Poor heat

[packratbimmer]

Have you measured your temps. at all of your hoses? If it is running too cold try an E36 88 degree stat. until spring

[E30andy]

Thanks again for all the help guys!

I would say my heat issue is better, but not solved.

Getting the recirc switch to work is definitely giving me more heat, but I still think there is an issue.

I dont think its normal to need the fan speed at 4, heat maxed, and recirc switch on (and fighting fogging windows) for my entire 20 minute drive to work (outside temp was 10 degrees this morning).

I may try to bleed again, although I have done that 3 times now with no change.

Das Delfin.....is there any way to check that recall temp cut off valve, or is it something you would just replace?

Thanks!

[muuris]

..A dial is another word for knob. Not a gauge ...

Haha, sorry, my bad :mrgreen:

If you didn't know, there was a recall for bmw in america which added another temp cutoff in place of the heater hose that flows from the t stat housing to the heater core inlet. It's a temp sensitive valve designed to cut off heat to the heater core in the event the engine overheats. This can fail and could cause problems similar to what the OP is having. I thought you knew about it but apparently you didn't...

Didn't know, as I'm not very familiar to America-only recalls and I haven't heard of similar recalls in Europe. I wrote about the "valve in system originally", I don't count recalls, they're not updated in ETM etc.

The main important is that the op got his heat issue solved :)

[Das Delfin]

Nice! Always glad for an easy fix!

[E30andy]

Ok guys, here’s an update....

So I took the console out and the valve is working, heater core gets nice and hot, no obvious issues with ducting being disconnected.

What I did discover is my recirc button wasn’t working. I monkeyed around with it and got it to work, and when it is on I get good heat from my dash vents and no cold air leaking through the direction control slider slots. My windows fog up though, which I was able to counteract by opening up the defrost slider.

So I was pretty satisfied with my heat on a quick test drive with the only change being a working recirc button.

[Das Delfin]

muuris, the temp dial is the temperature control knob to the left of the sliders in the hvac control region of the dashboard. A dial is another word for knob. Not a gauge or sensor or whatever

The temp dial (in the picture you quoted from me btw) is what governs the heater control valve. The same valve you've deleted.

If you didn't know, there was a recall for bmw in america which added another temp cutoff in place of the heater hose that flows from the t stat housing to the heater core inlet. It's a temp sensitive valve designed to cut off heat to the heater core in the event the engine overheats. This can fail and could cause problems similar to what the OP is having. I thought you knew about it but apparently you didn't...

[muuris]

Here another clue since I haven’t had a chance to tear into the dash to check the valve and flap.

I notice cold air coming through the slider slots for the air flow direction levers. That can’t be normal!

Any thoughts if that means anything?

Thanks again guys!

Sounds like disconnected or broken tubing inside dash.

You only need to remove the trim above driver's feet and center console to access the valve.

[E30andy]

Here another clue since I haven’t had a chance to tear into the dash to check the valve and flap.

I notice cold air coming through the slider slots for the air flow direction levers. That can’t be normal!

Any thoughts if that means anything?

Thanks again guys!

[muuris]

the temp dial sends an electronic signal to the heater core valve, which lets hot water into the heater core, heating the entire system.

The shutoff valve has no connection to the temp gauge or any sensor in E30.

The bypass valve muuris is talking about is deletable if you can find the original hose from realOEM. It was a recall to prevent a failing heater core from leaking scalding hot water onto the drivers feet.

I was talking about the shutoff valve, which is the only valve in the heater system originally. As in the pic from ETM you posted, it is controlled by a switch in the temp control dial. As mentioned before, it's normally open, meaning disconnecting either the dial or valve connector makes it open all time -- if the valve isn't stuck.




I've disconnected the valve connector in mine, meaning water is always flowing through heater core. As I live in Finland, this isn't a problem. Yes, it will heat up the dash and inlet air a bit even in the full cold position, but is better for the engine this way.

[E30andy]

Very helpful, thanks Das!!

[Das Delfin]

It sounds like your blend door may be partially open, but the heater control valve is what allows hot air to flow to your feet and windshield, and if you're not getting hot air there, your blend door isn't at fault

It's almost like your temp dial isn't telling the heater control valve to completely open AND isn't telling the door to completely shut. But since these two systems are controlled separately I'm not sure how one problem could affect both. You might have to take out your radio and its panel and check out the actuation of your bowden cables to start

here's a diagram from the bentley manual that may help


and another


this from the owners manual


This article may be helpful as well

http://www.e30zone.net/e30zonewiki/images/3/3d/E30_heating.PDF

there isn't a complete solution here, but hopefully this helps your thought process along

[E30andy]

the blend door you mentioned in your first post wouldn't prevent hot air from going to the windshield or foot panel; that door is only for the mid level vents. It works in conjunction with the temp dial - the temp dial sends an electronic signal to the heater core valve, which lets hot water into the heater core, heating the entire system. At the same time a bowden cable attached to the temp dial controls a flap door inside the heater box that allows outside cool air to mix with the warm air for the mid level vents only. The idea is to allow hot air to defrost and keep your feet warm while providing fresh air to your face to keep you alert.

That being said, I would say first to check your heater control valve since they like to stick, but if you said it's new (and assumedly plugged in and working correctly), then I'd try to make sure the heater hoses are plugged into the correct fittings on the heater core.

Your temp gauge is where it should be. The bypass valve muuris is talking about is deletable if you can find the original hose from realOEM. It was a recall to prevent a failing heater core from leaking scalding hot water onto the drivers feet.

Thanks Das!
I'm wondering again if the blend door is my issue?
I DO have heat at the defroster and foot vents, but NONE at the dash vents-unless thats the way BMW designed the system to work, as you mentioned? My 124 class Mercedes was the same way, only cool air from the center dash vents to "keep the driver alert".

[Das Delfin]

the blend door you mentioned in your first post wouldn't prevent hot air from going to the windshield or foot panel; that door is only for the mid level vents. It works in conjunction with the temp dial - the temp dial sends an electronic signal to the heater core valve, which lets hot water into the heater core, heating the entire system. At the same time a bowden cable attached to the temp dial controls a flap door inside the heater box that allows outside cool air to mix with the warm air for the mid level vents only. The idea is to allow hot air to defrost and keep your feet warm while providing fresh air to your face to keep you alert.

That being said, I would say first to check your heater control valve since they like to stick, but if you said it's new (and assumedly plugged in and working correctly), then I'd try to make sure the heater hoses are plugged into the correct fittings on the heater core.

Your temp gauge is where it should be. The bypass valve muuris is talking about is deletable if you can find the original hose from realOEM. It was a recall to prevent a failing heater core from leaking scalding hot water onto the drivers feet.

[muuris]

I have not tried checking the heater bypass valve, which the previous owner claims is new, but I am getting desperate, so that is my next task.

It's actually not a bypass as there is no alternative route -- it just blocks the flow from heater core. It should open when no electricity applied (or connector disconnected), but can be stuck.

Remove, disasseble, renew O-ring and put it back together. You need to drill rivets when disassembling and replace them with small bolts (M4) when assembling.

[spdracrm3]

Car is running again, weird issue....the fuel pump electrical connection was loose. Just jiggled it and it whirred back to life.

Anyway, back to my heat issue.

So I re-bled the system (didnt help, still only getting not very hot heat at the floor and defroster, cold air through the dash vents), and checked the hoses going through the firewall and they looked good.

I have not tried checking the heater bypass valve, which the previous owner claims is new, but I am getting desperate, so that is my next task.

Any tips on how to check it?

Thanks!!

Other than feeling or checking at the core with infrared tester. Easiest way is to remove and install a flushing T.if problem is solved you know it's bad

Sent from my SM-G360V using Tapatalk