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MG MGB Technical - The Dreaded Heater Valve!

Having had 3 heater valves fail in as many years-albeit for different reasons, I spoke to the supplier/manufacturer. He made a couple of relevant suggestions. Do not leave the valve in the off position if the car is not being used for a while (winter?). The valve may stick in the this position and when trying to open the valve the rubber diaphragm splits. (Mine had) Having dismanted the valve it would seem that a mid position (for the valve-never mind the knob)would allow the diaphagm to be "under least tension " in either direction. Even to the extent of simply releasing the cable. Best thing though is to drive the car more!! He also pointed out that for those of us with fine mesh under the grill in front of the screen, the airflow is considerably reduced. He suggested a 1/4" mesh. Having said that mine has acetate under it to stop the icy blast in winter! I did consider the Plumbers Tap arrangements but judging by the crud in the dismantled valve, a plumbers ball valve would be as likely to stick. PS Life expectancy of a heater valve is "about 5 years...."
Michael Beswick

I think the B valve is an over complicated mechanism. The one used on the RV8 is much simpler and less likely to block, split etc.. It's basically a ballofix valve, no slots and grooves etc..
I have one on my V8 conversion and it works well. Finding suitable valves is a problem though. VW do a similar one for Mk 1 Golf's and the later Transporters, but the orientation is different.
Allan Reeling

A pal is making up one using a plumbers "ball type" valve. I'm just not sure how it will cope with the crud that was evident in the bust regular valve!
Michael Beswick

We have the plumber's "ball type" valve in two of our three B's. They work just fine. :)

TheMiz

My last heater valve lasted only 7 months. Not good enough for me. I gutted the failed valve and replaced the diaphragm with a steel disc. Then I added a ball valve in line between the old valve and the heater core. I used the illustrations on Bob Muenchausen's web site for inspiration. Google "Bob Muenchausen MG heater valve". I'll attach a photo of mine. -G.

P.S. Been talking with Moss Motors about improving the rubber in the stock replacement valve.

Glenn G

Gentlemen, you want to come and live in Queensland. I have no heater!
J.M. Doust

J.M., how do you manage without the extra cooling the heater offers?
Mike

For the moment I have fitted a standard valve whilst my plumbers ball type is made up. Will post a pic when it's ready-it's similar to yours, Glenn, but I have not used the old valve body. We are soldering /brazing a copper bend on to a flange that fits to the block, then a very short piece of 1/2" copper pipe into the valve and a slightly longer piece for the outlet to the hose. (Compression fittings in the ball valve bit) The operating cam will probably be mounted on the outlet pipe, but it's rather a work in progress!
Michael Beswick

I took my heater valve off this morning as I am changing the head. The heater valve was blocked at the mounting face by a light coloured crystaline substance. I assume this is the result of electrolytic action. Has it happened because there was not enough anti freeze in the water?
David Witham

The replacement heater valve, on my '67, is now over 20 years old. It never leaks and is left in the closed position for months at a time. The quality of the valves today is absolutely horrible. When mine does fail, I'll use one of the inline ball valves as a replacement. The better quality ones use a stainless steel ball riding in a Teflon coated housing. RAY
rjm RAY

David -I use 4life and had a similar (pink) crystaline/hard crud. What I did discover by blowing through the valve, is that fully on and fully off are achieved way before the end of the "ramp". After a first run it appears to turn fully off and on at the points, which coincide with the click when you turn the dash control. Doesn't alter the quality aspect but maybe it's a factor in premature failure.

Michael Beswick

Simpler than most:

http://www.britishcarforum.com/bobmuenchausen/12272.html

Been doing these for a dozen years.
BobMunchausen

Thanks Bob I'd been looking for that site!
Michael Beswick

I burst 3 valves in 2 years. The Chinese rubber is no good. This is a daily driver. I changed to an RV8 style cable operated ball valve, $60 Aus. VW rabbit/golf valves are also popular/cheaper.
If you don't want to use Bobs clever solution for the water outlet then hunt up a Leyland marina at a wrecker/breaker and get the heater/pipe off it. It essentially has bobs adapter. Lots in the UK, few in the US
Peter Sherman

BTW, anyone wanting a prettier replacement for the sawn off heater valve for a base, can get a very nice unit from here:

http://pembrokeparts.com/PHF.htm

Looks like he has made a kit for the whole shebang. See where a Saturday afternoon over a dozen years ago and sea of bad OE type heater valves have led??? LOL!

Cottage industries!!!
BobMunchausen

http://www.apairinc.com/detail.asp?Part=570-211


http://www.mgexperience.net/phorum/read.php?1,1246171,1246171#msg-1246171

Peter Sherman

Whilsy MOTing a Toyota Corolla (MY 2000) I noticed it had a suitable valve tho I think a larger bore pipe. Unfortunately we are discouraged from dismantling customer's cars in for test, so I was unable to check furhter.
Michael Beswick

The TR6 uses more or less the same valve [just a different mounting] and Revington have developed a replacement for several TR models and also a universal one http://www.revingtontr.com/shop/collection_display.asp?CID=695
It's a bit pricey and I've no personal experience of it but their stuff is usually good.
Ron
R. Algie

I went and bought the RED DOT valve today. The Push to open. 3/8ths hose. I've had a push to close versio for years and its worked perfectly.
looked like this exactly, well made.
http://www.apairinc.com/detail.asp?Part=570-211
You need to search red dot and their distributors, who are usually whole salers.
http://www.rdac.com/find-a-dealer

Find out from those middle men who their distributors are, and and ask them to order a part. It cost me $39 OZ$, which isn't too bad. In the USA these are around $20.
At twice (edit Four times!) the price that kit had better include a block adaptor, I think.

here is the part numbers from Frank

72R5060; RD-5-5119-0P

they only wanted to know the first number when I called the red dot distributor.
Peter Sherman

In all the searching for the ultimate valve, don't forget that the limiting factor is not the size of the valve past a certain point, but the ID of the inlet pipe to the heater core and the outlet pipe as well. It can't hurt to have as large an opening in your valve and all the plumbing from the head leading up to it and from it to the heater inlet and beyond. But unless you choose to resize the inlet and outlet too, you won't gain much in flow, altho certainly more than if you hadn't paid some attention to the sizing of these components.
BobMunchausen

This thread was discussed between 28/03/2011 and 09/04/2011

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