Heater Control Valve

Technical MGB discussion
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SteveH1960
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Joined: Thu Jul 01, 2021 4:23 pm
Forename: Steve
Surname: Hankins

Heater Control Valve

Post by SteveH1960 »

The heater control valve knob on my 72 B is extremely stiff and doesn't run through the full range.

I checked the heater control valve on the engine, which is stuck mid way. I disconnected the cable to try and move it manually (the valve on the engine) and when putting it to fully on water leaked out. I assume the valve is knackered and I need to fit a new one?

Are these easy to fix?

Thanks
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Charles Farran
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Forename: Charles
Surname: Farran
Location: Warwickshire

Re: Heater Control Valve

Post by Charles Farran »

Hi,
The heater valve on.the engine block is a known weak point . Easy to change, but you will need to drain the coolant down to below it's level. Good opportunity to have a complete rerllush of the coolant etc. Best to get an O.E. replacement of the heater valve + a gasket. When refiiting, ( & before installing) blow through the valve & mark on the body when it is closed. . You will then know at which point the cable should be fixed. (This prevents you from putting to much strain on the valve when using the control in the cabin which shortens the valve's life).
Cheers,
Charles
1980 Roadster
SteveH1960
Posts: 14
Joined: Thu Jul 01, 2021 4:23 pm
Forename: Steve
Surname: Hankins

Re: Heater Control Valve

Post by SteveH1960 »

Thanks Charles, the nuts look bloody difficult to access. Any special tools needed or just accept skinned knuckles?
I've read it may be an idea to use allen headed machine screws, probably as rare as rocking horse poo
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Charles Farran
Posts: 360
Joined: Fri Oct 31, 2014 11:08 am
Forename: Charles
Surname: Farran
Location: Warwickshire

Re: Heater Control Valve

Post by Charles Farran »

Hi,
To remove the valve from the block there is just room to use a small combination spanner with a ring at one end & open ended at the other end, alternating as required. When replacing I used a trace of copper ease.
When replacing the srews,,if using new ones make sure they are the same length as the originals.
Cheers,
Charles
1980 Roadster
JohnH
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Joined: Wed Apr 03, 2019 11:12 am
Forename: John
Surname: Howard

Re: Heater Control Valve

Post by JohnH »

Good trick for draining down to do heater valve is to disconnect heater hose at front of engine and insert a smaller tube down to and inside the bottom hose and siphon gently. Try not to get a mouthful!
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