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MG MGA - Water Valve Assembly help

I normally run my 1960 Mark I with the heater control permanently set to warm to help keep the engine temperature down. A complaining passenger asked me to set it to cool last weekend which I did. Without knowing it while driving the valve immediately started leaking coolant, but only when set to cool. The leak stops if moved back to warm. This coincides with the engine misfiring which I initially put down to a sticking fuel pump which has happened to me before.

Would a leaking valve give misfiring symptoms and do I need to replace the valve or is would it be a gasket of some kind? I have no idea if the valve is serviceable. The coolant is leaking from the diagonal slit in the cone.

Thanks and Safety Fast!

Jason
Jason Ogelman

Jason, if it is spraying water all over the plug leads I'd say its a fair chance that's the problem
Art Pearse

Fluid coming out the top slot means it has a ruptured rubber diaphragm, goner for sure. Just get a new valve, not too expensive, and I don't know where to get a new diaphragm anyway.

Just replaced mine last week. Prior new heater valves have lasted 202,000 miles, 166,000 miles, and this one only 41,000 miles in 14 months. Disappointing.
barneymg

Yes - mine did that too - together with misfiring as a jet of water was squirting over the dizzy cap
Cam Cunningham

Here’s what I have done in my MGB and my MGA without any problems after more than a year in both cars. At a glance, you don’t even notice that it’s not an original-style heater valve when installed.

https://www.mgexp.com/phorum/read.php?2,2972633,2972633#msg-2972633

Jim
JL Cheatham

This heater control valve is a popular option for installation on Triumphs as well. See attached link; lots of photos & commentary:

http://tr6.danielsonfamily.org/HeaterValve.htm

Nick Kopernik

This thread was discussed between 23/07/2018 and 05/08/2018

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