'86 280i-Want to install heater isolation valve

[MCWEDGE]

MCWEDGE does not have a heater control valve. It has a flapper/door that allows air to either pass over the heater matrix/core or the AC evaporator. I would like to eliminate as much hot air in the cabin as possible in the summer, as the AC is currently not performing as it should. First step might be to prevent any hot coolant from flowing through the heater matrix. In Steve Heath's manual, on page 82, he shows what he calls a heater isolation valve, installed for just this purpose, but the photo is not very good. Has anyone installed a similar valve, and if so, have any photos of it. I know this isn't rocket science, but perhaps someone has found a really good solution that I could also use.

Jim McPhee
Placitas, NM

[KKson]

Hi Jim, hope all is well. All 350is and later have the isolation valve. It's an inline item, cut unto the heater feed line in the engine bay, close to the bulkhead. On the three Wedges I've had, they also have a smaller diameter bypass hose, before the valve, so even if it's closed there is still a small flow on the heater feed and return lines. My heater is currently by passed after the matrix expired in a cloud of steam the other week. I'll get a photo of the unit which I think was used in many British cars such as Mini, Triumphs etc. Any inline valve would work though. Cheers Keith

[KKson]

Hi Jim, photo of heater valve, and also small bore bypass line. Plastic hoop thing and bent bit of hose are temporary bypass to isolate leaking heater matrix

This is what you need. I'm sure you can get one your side of the pond. Cheers https://www.demon-tweeks.com/demon-tweeks-plastic-...

Edited by KKson on Sunday 18th June 10:14

[MCWEDGE]

Hello Keith,

Thanks for your reply and for taking the time to provide the photos. Yes, that's just what I was thinking. Amazon has quite a selection of heater valves, both metal and plastic. I wasn't sure I could tap into the matrix inlet hose and attach the valve to the bulkhead as well. But, if the valve is light enough, I doubt it will put much of a load on the heater hose so probably no need to anchor it to the bulkhead. And I won't need a control cable. I'll just shut it off in the spring and open it back up in the fall. Is the bypass line necessary, do you think?

Cheers,

Jim McPhee
Placitas, NM

[KKson]

I think the bypass line will ensure there are no air locks in the system. Personally I'd include a small bore one mine has two plastic tees. I think they are 5/8" main bore and 1/4" on the small outlet. Cheers

[MCWEDGE]

Hi Keith,

I just learned that the heater hose on the left side of the Cologne engine wedges, the one that goes right through the bulkhead, is the outlet from the heater matrix, not the inlet. That's going to make it more difficult to install a valve as the outlet comes up from underneath on the right side and has a bunch of other lines around it. I guess the Rover engine wedges have the inlet on the left side near the bonnet latch?

Jim McPhee
Placitas, NM