Heat not working

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Heat not working

Post by Emil.ahnberg »

Hello! I have a bmw e28 518 from 1987/88. As usual the heat isn't working. I have a radiator from a volvo 740 etc. The system works fine and runs good. The problem is that i dont get any heat at all in the car. Ive checked the "valve". A metal wire runs to what i guess is a valve that opens the hot water to the heater. The valve would move when i wiggled it a bit, fist it pointed to the engine block, which i guess is the closed position?? one of the hoses was realtivly warm. I just drove for like 10min. Does anyone know what could be broken/not working corectly etc.


I havent found anything on mye28 about this. If there already is a thread about this please send it to me.:)
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

Will add to the post that ive tried to get all the air out of the system, but maybe it wont work if the valve was closed?
stuartinmn
Posts: 9397
Joined: Feb 12, 2006 12:00 PM
Location: Minneapolis

Re: Heat not working

Post by stuartinmn »

Can you feel any heat when the car is stopped and the engine is just idling? If so it may be a defective heater valve, which is a common failure. I'm not sure if replacement valves are still available from BMW but there are aftermarket rebuild kits. See this discussion: https://www.mye28.com/viewtopic.php?f=9&t=17342
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

No. i dont get any heat whatso ever. :(
Aldo525
Posts: 306
Joined: Mar 24, 2021 3:04 PM
Location: CHILE

Re: Heat not working

Post by Aldo525 »

Hello, I've an e28 518i Sweden version.....the car have a manual/mechanical heater valve, not the electric heater valve (I think all e28 US version use the electrical valve, same as "higher" euro versions) so the warm water enter the heater core just opening the valve using the cable commanded knob in the dash...very simple system. One possible problem could be a clogged heater core, remove both hoses and try to put running water from one end....until water flows normally in the other end (one is the inlet, the other the outlet). The valve itself is simple, just check if there is free cable movement when turning the knob. Warm water moves from the rear end of the head, pass through the valve, then the heater core and returning to the rear of water pump in front of the engine, so my guess is a clogged hose, clogged heater core or maybe low water pressure if the water pump is not good, but engine overheating should be obvious.
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

Okay i will try, i also have a swedish one. Do you know which position is open/closed? The waterpump is relativly new and the engine dosent overheat. Does the water flow easily to the heater core or do i have to jack up the front like the newrer bmws?
Aldo525
Posts: 306
Joined: Mar 24, 2021 3:04 PM
Location: CHILE

Re: Heat not working

Post by Aldo525 »

Emil.ahnberg wrote: Mar 22, 2024 8:36 AM Okay i will try, i also have a swedish one. Do you know which position is open/closed? The waterpump is relativly new and the engine dosent overheat. Does the water flow easily to the heater core or do i have to jack up the front like the newrer bmws?
This afternoon I'll take some pictures on the valve open and close to share. With engine running, the hose in the rear of head should have a good water flow, good enough pressure to travel all over the heater circuit across the heater core and so on.....but if before the valve there is no good flow pressure so the problem could be too much air in the water circuit...
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

Okay Thanks! Best way to check if water comes to the valve and have good pressure? I don’t want to soak everything in warm water if I have decent pressure. I’m gonna flush some water trough the heater core to see if it’s clogged.
Aldo525
Posts: 306
Joined: Mar 24, 2021 3:04 PM
Location: CHILE

Re: Heat not working

Post by Aldo525 »

Emil.ahnberg wrote: Mar 22, 2024 12:52 PM Okay Thanks! Best way to check if water comes to the valve and have good pressure? I don’t want to soak everything in warm water if I have decent pressure. I’m gonna flush some water trough the heater core to see if it’s clogged.
What I would do to see the flow would be to disconnect the heater core (both hoses) and connect both hoses with a piece of transparent tube (10 cm). That way you would see how the water flows from the cylinder head to the back of the water pump. In the same way I would test if closing the water valve stops the flow to the water pump.
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

Alright, that’s a gods idea! Will try indeed, thanks!
Aldo525
Posts: 306
Joined: Mar 24, 2021 3:04 PM
Location: CHILE

Re: Heat not working

Post by Aldo525 »

Emil.ahnberg wrote: Mar 22, 2024 12:52 PM Okay Thanks! Best way to check if water comes to the valve and have good pressure? I don’t want to soak everything in warm water if I have decent pressure. I’m gonna flush some water trough the heater core to see if it’s clogged.
These are the knob/valve open and closed

Closed
Image

Open
Image
Mike W.
Posts: 26936
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Heat not working

Post by Mike W. »

The valve is very reminiscent of the late E21 heater valve, a nice simple design and a lot more reliable than the electric one we got here in the states.

But one more vote to just flush the heater core. Just use a garden water hose and try running water thru it in both directions a couple of times. I've found if heater cores are plugged and flushing works, it tends to plug up again after not too long, I've had that happen on several cars over the years. But at least it gives you an idea of what's going on and to perhaps put a filter on it if that's the problem.
Theotherotter
Posts: 94
Joined: Jun 21, 2023 9:14 AM
Location: Chicago

Re: Heat not working

Post by Theotherotter »

This looks like a more robust control and valve design than what comes on my E12, and probably a lot more available. In principle, I’d love to retrofit this knob, control and valve to my E12.
Mike W.
Posts: 26936
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Heat not working

Post by Mike W. »

Theotherotter wrote: Mar 24, 2024 2:12 PM This looks like a more robust control and valve design than what comes on my E12, and probably a lot more available. In principle, I’d love to retrofit this knob, control and valve to my E12.
The E12 ones work ok, and are reliable for ~200K or so, but are a holy bitch to replace and now NLA.
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

Hello, it now been solved and i get heat. The valve was quite stuck and the heat knob dont work, but i can manually change the temprature if i open the hood and close/open the valve. I dont get 30 celcius but its atleast warmer now. Ill try to flush the system so that its not clogged. Thanks for all the help!
Theotherotter
Posts: 94
Joined: Jun 21, 2023 9:14 AM
Location: Chicago

Re: Heat not working

Post by Theotherotter »

Mike W. wrote: Mar 24, 2024 4:44 PM
Theotherotter wrote: Mar 24, 2024 2:12 PM This looks like a more robust control and valve design than what comes on my E12, and probably a lot more available. In principle, I’d love to retrofit this knob, control and valve to my E12.
The E12 ones work ok, and are reliable for ~200K or so, but are a holy bitch to replace and now NLA.
Tell me about it. Mine failed last week in an unexpected way when I was replacing a broken U-joint on the control. Now it jus dumps coolant on my foot and the carpet so I can't drive the car until I fix it unless I can find a way to effectively plug and seal the hole where the control head goes. Looking at your manual E28 valve. I doubt it can easily be adapted to an E12 since water inlet and outlet are on opposite sides.

A couple of people have told me that they got new E12 valves from a dealer (in Europe) as recently as last year. I'm hoping I could be so lucky, even if it's in Europe (I'm in the US).
Aldo525
Posts: 306
Joined: Mar 24, 2021 3:04 PM
Location: CHILE

Re: Heat not working

Post by Aldo525 »

The parts to replace the control and the water valve still exist, but not the bowden cable, but I don't think it will be difficult to make one (or adapting one of the air vents, looks the same but longer). The location of the temperature knob on the models with and without AC are similar, so I think it shouldn't be too complicated to retrofit the valve and knob from an automatic one to a manual one.
The parts are:
Command (#11 in picture): 64111373938

Image

Valve (#1 in picture): 64211368650

Image

Bowden cable (NLA)

Image
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

Alright, Will see iF its broken or it might could be fixed. How do i tear down the climate controll without breaking anything? What i understand i need to remove quite alot of things?
Mike W.
Posts: 26936
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Heat not working

Post by Mike W. »

It's reasonably straightforward, but 40 year old plastic tends to be fragile, be as gentle as you can. Might be that one of the clips that retains the cable has popped off, it would be nice to find it, but if not a cable tie can usually be used.
Emil.ahnberg
Posts: 12
Joined: Nov 05, 2023 3:25 PM
Location: Sweden

Re: Heat not working

Post by Emil.ahnberg »

Yes, the things is i dont really know how to get the climate controll panel off. What i can se its hold in from 2 screws/clips from the sides or uppwards the panel. I saw some threads here that you can remove the radio etc. But i have a screen thats stuck with rivets for the air suspension under the climate control panel in the radio spot. maybe there are any way of getting the panel out?
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