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E36/E46 heater control valve retrofit for your E28

A heater control valve solution for our 80s BMW

Learning context

The heater control valve in our cars controls the flow of coolant from the engine that enters the heater core and radiates heat into the cabin of the car. Unfortunately, after thirty-plus years, the heater control valves are fragile and break. This is what happened to me when I was replacing the starter in my Bronzit E28 four years ago, instead of paying the crazy amount for OEM replacements I just connected the hose direct to the heater core. This meant that I had hot coolant radiating heat into the cabin year-round, and as the summer is here I was motivated to finally fix it. After some research, I found that the e36/e46 heater valve has the hose connections in the correct direction to fit in our E28s.

Helpful link

I found a lot of useful information from a post about this retrofit on Mye28.com, I strongly advise any E28 owner to create an account with Mye28.com because it has a lot of useful information.

Mye28.com forum post on how to retro fit the heater valve

In this forum post, I also found a guy that sells 3D-printed brackets that would reduce the headache of mounting the valve to your E28. I found this information after I had created my bracket so I ended up not taking advantage of the 3d bracket. Hit up szacsi72 if you are interested in a complete retrofit kit with heater valve and bracket, or just want to get an excellent quality bracket.
Adapter only $15 plus shipping
Retrofit kit $140 plus shipping

Summary

  1. Drain coolant
  2. Fabricate a bracket
  3. Figure out the coolant hoses
  4. Parts/Tools

Procedure

  1. Jack up the front of your vehicle and safely place it on jack stands. I used Angry-ass jack pads and jack stand pads to get my E28 on jack stands. I highly recommend these jack pads when working on your ride.
Angry ass jack pads and jackstand pads to safely jack your ride up.

2. Locate the drain plug at the bottom of the radiator on the passenger side, to reduce the coolant spill I used a fountain drink cup with a hole at the bottom to undo the drain plug and drain the coolant out of the radiator. It’s a good idea to remove the cap on your coolant expansion tank to prevent a vacuum from allowing the coolant to drain better.

3. The OEM heater control valve is mounted on the firewall, and this is how the E36 heater control valve will sit once it’s installed.

OEM heater valve mounting point.
E36 heater valve

4. Originally the orientation of coolant flow was the top hose is inlet and the bottom hose was the outlet, but to make this heater valve work you need to reverse the flow.

5. After figuring out the hose orientation, I worked on the bracket upstairs. I purchased some sheet metal from Homedepot for $12.00 and measured out the spacing of the holes on the heater valve. I drew some crude lines but the idea is to find the center and then mark the holes onto the plate. The spacing for the top holes is 55mm center to center, the bottom hole I ended up not using because of space.

6. After making the bracket I used my tap and DIY kit to tap the control valve holes to M7 bolts. By this point it was late evening, the next day I ran to the hardware store and picked up some hardware to bolt the bracket up to the valve.

7. To demonstrate how the hoses are going to run I mocked up the pieces together on my bench. Cut a 3-1/2 inch piece of 3/4 coolant hose to attach the elbow to the top nipple of the heater valve. The U hose hooks up to the elbow like the picture below, and the hose from the back of the engine hooks up to the second nipple. This is the way it’s going to go on in the vehicle.

8. As I had mentioned in step 6 I ended up only using the top two mounting holes because of space. So I cut the bottom part of the bracket and mocked it onto the firewall as a fit test. I ended up moving the bolt retaining clip from the left mounting hole onto the center and flattened the right mounting bracket to fit the bracket

Heater valve location
Mocking up the plate for the heater valve in my e28

9. Mount the heater control valve onto the bracket and bolt it up to the firewall. Something I might do is redrill the holes to be able to shift the bracket over to the driver’s side as much as I can, I did not plan that the hose nipples on the valve are angled slightly and not straight.

Home made bracket for E36 heater control valve
E36 heater control valve installed in my E28

10. I had cut the coolant hose too short and had to get another foot of hose. But once it is all hooked up I noticed that the pigtail I received only had one cable and not two. I am currently waiting on a replacement to be able to wire this thing up.

E36 heater control valve pictail.

Conclusion

The hardest part of this entire retrofit was the bracket, but if you take advantage of the 3D-printed brackets this is straightforward. All of the parts except for the heater control valve and the pigtail I purchased them from Oreilleys. All said and done it cost me around 110 dollars not including coolant to refill the vehicle. A small piece of information about the heater control valve, if you order it from FCP Euro which I linked in the tools and parts list you get LIFETIME REPLACEMENT on it. If it breaks you just contact FCP Euro to ship the old one and get a new one, you can’t get that great deal from an OEM heater valve that’s for sure.

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