Heater valve replacement

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Theotherotter
Posts: 31
Joined: Mon May 15, 2023 6:16 pm

Heater valve replacement

Post by Theotherotter »

My heater valve failed recently and after a lot of procrastinating by focusing on my 911 instead, I finally got started on it last weekend. I was familiar with the two options (in situ, high degree of contortion, bending a 9mm wrench, doing things blind, etc. per the FAQ here; or start ripping things out) and decided ripping things out would be less bad. I was fully expecting to have to pull both the AC module out and then the heater/blower assembly to replace the valve on the bench, but I was pleasantly surprised to find, once I got the AC out, that it looked like I could get to the two inaccessible nuts without taking it out. I got one coming from the passenger side and the other from the driver side by dropping the steering column so that I could get the wrench in at the right angle. Saved me hours of work.

I'll update with photos, etc. later once I've finished. Old valve is out, have a NOS one ready to go in. I have two broken swivel joints (one on the heater control, one on the air distribution control) but only one replacement joint, so I'm thinking about DIY options that use the broken stub of the swivel joint, like a U joint from a robotics catalog. It's also tempting to adapt an early E21 heater valve, which has the same geometry as the E12 valve (in and out on the back side, the inlet and outlet mounting studs appear to be in the same location and orientation as the E12 part) but with a lever arm for a Bowden cable on the front side, using the back end of a later E21 control knob with its lever arm and figuring out the Bowden cable if a BMW one isn't available. But I already have a NOS E12 valve.
Theotherotter
Posts: 31
Joined: Mon May 15, 2023 6:16 pm

Re: Heater valve replacement

Post by Theotherotter »

No photos, but an update. I decided to experiment with the swivel joints first. I found the thick 3M VHB tape that I have, and used it to reattach my broken U joints.

On the right side (air direction), this failed quickly because when the flapper door closed all the way, the last little bit of knob travel pushed the edge of the door over a lip, and the extra force tore my kludged U joint apart. No problem - I redid it with the joint clocked about 30 degrees off so that max knob travel was when the door hit the lip but before it went over it. This has held up for a while now.

on the left side (heater valve), this lasted only a short time before the tape tore off - the friction of opening the heater valve puts more non-shear force on the tape than it can handle. It won't be cold for a while and if I need to adjust the temp control I can reach in between the column and console and adjust it manually (that little piece of my knee panel cover is broken and was fixed earlier in a way such that if I don't use the attachment screw I can just pull it down.)

Will come up with some kind of U joint solution for the left side for sure.
dutch
Posts: 46
Joined: Sat Apr 15, 2023 8:22 am

Re: Heater valve replacement

Post by dutch »

Looks like those joints can still be ordered from bmw...? I see them listed for like 10 bucks each... On a side note; I have ordered parts and gotten refunds a day later because the part wasn`t available after all...
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Mike W.
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Location: Sonoma County

Re: Heater valve replacement

Post by Mike W. »

Theotherotter wrote: Thu Aug 29, 2024 3:37 pm

Will come up with some kind of U joint solution for the left side for sure.
After much thought, I think I'd try a piece of rubber hose. Maybe vacuum line even, it's softer and more flexible.
Mike W.



02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
Theotherotter
Posts: 31
Joined: Mon May 15, 2023 6:16 pm

Re: Heater valve replacement

Post by Theotherotter »

dutch wrote: Fri Aug 30, 2024 3:06 pm Looks like those joints can still be ordered from bmw...? I see them listed for like 10 bucks each... On a side note; I have ordered parts and gotten refunds a day later because the part wasn`t available after all...
They show up on some sites, but they’re not orderable anywhere. I called a local dealer last year and they said they’re unavailable all the way back to warehouses in Germany. They had been on either Pelican’s or FCP Euro’s site last year and I called, skeptical; they later confirmed that they were indeed NLA. I got a couple of used ones locally but one broke, so I’ve got one good one left.
Theotherotter
Posts: 31
Joined: Mon May 15, 2023 6:16 pm

Re: Heater valve replacement

Post by Theotherotter »

Mike W. wrote: Fri Aug 30, 2024 6:54 pm
Theotherotter wrote: Thu Aug 29, 2024 3:37 pm

Will come up with some kind of U joint solution for the left side for sure.
After much thought, I think I'd try a piece of rubber hose. Maybe vacuum line even, it's softer and more flexible.
How did you envision using a rubber hose?

My idea involved a U-joint of the type used for robotics. I can’t find the link I had saved, but it was a joint of about the right size with a mounting face that would work well with the remaining pieces of the OE part.
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Mike W.
Posts: 2817
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Location: Sonoma County

Re: Heater valve replacement

Post by Mike W. »

Theotherotter wrote: Sat Aug 31, 2024 11:30 am
Mike W. wrote: Fri Aug 30, 2024 6:54 pm
Theotherotter wrote: Thu Aug 29, 2024 3:37 pm

Will come up with some kind of U joint solution for the left side for sure.
After much thought, I think I'd try a piece of rubber hose. Maybe vacuum line even, it's softer and more flexible.
How did you envision using a rubber hose?

My idea involved a U-joint of the type used for robotics. I can’t find the link I had saved, but it was a joint of about the right size with a mounting face that would work well with the remaining pieces of the OE part.
My thought was to wire it to the flat flange, either whole or split so "ears" would be flat against it, then probably sleeving it onto the shaft. I've got those pieces, I could look, but haven't yet, I'm just working off my minds eye.
Mike W.



02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
Theotherotter
Posts: 31
Joined: Mon May 15, 2023 6:16 pm

Re: Heater valve replacement

Post by Theotherotter »

Ah, I see. My thought was to epoxy bond a U joint to the flat disc, and then it could slide onto the shaft.
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