Heater core isolation

[PtFosdick]

On my 63 Morris Cooper S I have an "upgraded" heater labeled British Leyland,
so newer than the car. it has the proper heater cable operated valve on block.
However, when I shut off the valve ( I freed up the cable and valve connections) I still get heat through the core. I would like to shut the core off in the warmer months (car runs cool enough I think) and wonder if a small brass shutoff valve in the return hose would make that happen and if there is a downside to that (or other ways to do this). Any suggestions would be appreciated.

[Dixminion]

Why not replace the valve on the head?

Don

[PtFosdick]

Valve works?

I think the head mounted valve probably works, I have been told that the heater can still heat up from the coolant in the return line, but I am a real novice (actually, more of a dummy) on mechanical stuff, how would I easily check function of the valve as it moves fully and smoothly?

[Jerry]

I agree with Don, I'd suspect the heater valve on the head. The water flow is from the heater valve to the heater core, then back to the engine, so it seems to me that water might be leaking through the valve.

[mascher]

There are heater valves that work opposite of what you would expect. These are later valves. It may be open when you expect it to be closed.

Kelley

[Dixminion]

It could also be like an igloo to a polar bear.. solid on the outside, chewey on the inside. The rubber insides could be shot while the outsides look good. A new stock valve is an inexpensive and proper fix.

Don

[Cheleker]

Unfortunately, heater valves that sit on the head have never been the most reliable. OK, but not real reliable. I solved that problem by leaving them on all the time.
The latest generation of valves have been added to my list of things that they just don't make like they used to. There are a couple of types out there and one (with the curved arm and captive trunnion) is on my Don't Use list. There have been enough complaints that they will be fixed. When? I don't know.

[PtFosdick]

Heater core isolation

Thanks for all the input, Chuck you mentioned some replacement valves may not be reliable. Which ones specifically would be a pretty good bet? I'll go that way thanks to all.

[Jerry]

Seven enterprises has them on sale for $45. P/N ADU 9102.

[Cheleker]

Depending upon where you buy (and where the supplier gets stock) ADU9102 can be a good thing...or a bad thing. Mini Mania, for instance, lists an ADU9102 and an ADU9102-ORIG. Currently, the ORIG (the one with the curved arm) is the one to stay away from. The one with the straight arm with the holes in it works OK. (Note that it does not come with a trunnion for the cable so you have to buy that, too.)
N.B.: What's good and what's bad changes...tomorrow, or next week, or a month from now as old (bad) stock is sold off (no "recalls" for us in the Mini world!)! and new (fixed) stock becomes available. There's no way to know without trying one, unfortunately. Also, some parts are sourced from different companies. Seven's ADU9102 looks like the same one that is causing all the problems, now. But if they get it someplace other than where MM gets it, it may be fine.