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MG MGB Technical - Heater Valve

Today I noticed I had water dripping from the heater valve, it was dripping off the end of the control cable. I assume this means I need to replace the valve. Any tips on this job? I assume it's fairly straight-forward and gives me an excuse to clean out the cooling system.

Also are all the replacement valves the same quality? Is what you get from Moss OK?
Many thanks
Kevin
K M Sheahan

Check the archives. There are complaints that the new valves don't flow as well as the OEM ones resulting is lower heater output.

I think you'll find threads on how to modify the new ones if you want more heat, how to use alternatives such as ball valves, and how to repair the old ones (not easy).

Otherwise I think replacement is pretty straight forward.
Robert McCoy

Yes it's off with the control cable, 2 bolts out and re-fitting is as they say the reverse. This seems to be another area where replacement parts are of lower quality than the British made OE fit. My car is still on its original valve and it has never had a problem.
Stan Best

I fitted a 1/4 turn ball valve to mine just the weekend. Replacing the valve is easy.
What I am wondering is the best system to use to refill the system. Since the heater is above the radiator I wasn't sure the best way to get all the air out of the system.

In the end I removed the left hand side hose at the heater end, opened the valve and blew down the hose until water came out of the heater. I also poured water down into the hose before quickly refitting it.

How does any air left in the system get out?

Simon
Simon Jansen

"How does any air left in the system get out?"

Not tryin' to be a smart-a** here (I do that enough without trying!), but I think 3,000 rpm helps. ;)

Seriously, it's pretty self-correcting. It's easier on the earlier cars that have an honest-to-goodness radiator fill cap, but between revs and heat expansion you're gonna be okay.


Rick Stevens

Ah, I figured that must be the case!

I find with the later cars with the cap on the expansion tank you can get most of it out by squeezing the top hose. It forces the air out and then will suck in fluid to replace it.

The 3000rpm method sounds more fun though :)
Simon Jansen

Thanks all, I've ordered the heater valve & gasket so a job for the weekend.
Regards
Kevin
K M Sheahan

This thread was discussed between 08/06/2008 and 11/06/2008

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