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MG MGB Technical - Heater Control Valve

Will a midget heater control fit on an MGB? I saw one posted on eBay and thought that would be a great solution to replace the overly complicated MGB design and not be prone to leaking on the dizzy.

Just a thought.
Mike MaGee

MIKE,
Check this out: http://www.cibolas7.net/12272.html It will mean some fabrication, but I think you have the tools to do this.
Bob Muenchausen

bob's suggetion will work. i chose a different type, but it functions and does not require you exit car to control the output. you would do as indicated in the first step, but then use a 1/2" or 5/8" hose barb for a short length of hose, then add a early Ford truck heater control valve
(years are 65-85?) they require 5/8" hose & are controled by a cable same as mgb. i bent the cable end around control post on the valve and fixed the cable hsg with the clamp included with the valve. be sure there is adequate travel prior to cutting the inner cable wire. next, you reduce the 5/8" to 1/2" and connect to the MGB heater tube. you can solder some copper water pipe fittings (Home Depot) to make this transition from 1/2" to 5/8". may seems like a lot of work, but my heater actually works. does not hurt that i have 5.0 Mustang engine and drive train creating heat.
Stay dry & warm
kelly stevenson

Bob, I did your modification on my car recently when the OE type heater valve started dripping coolant. We went for a 100 mile drive today, it was cool outside but not cold. We are both over 75 years old and cannot stand cool weather like we could 20 years ago. With the heat on we had to remove our light coats in about 10 miles, after 20 more miles it was time to turn off the heat. Thanks for posting the article, I'll never install another MGB OE heater valve.

Mike, I had a Midget several years ago and I believe the valve is threaded into the block, the hole in the MGB block may be too big to thread for the Midget valve.

Clifton
Clifton Gordon

Mike,

Another solution is to use the water elbow from one of the many other B series applications - these can be found on some Marinas and Austin 1800s in the scrap yard or you can make one up - it is just a simple elbow brazed to a steel plate that bolts to the head in place of the OE valve.

Connect this to a MGC remote style valve which has two hose pipe connections and you will have a full flow valve that can be controlled from inside the car but can be positioned well away from the disi.
Chris at Octarine Services

I recently celebrated the onset of winter by turning the heating on. It will stay on until april sometime when it gets truned off for the summer.

Maybe a solution like yours would provide much need flexibility!

Cheers,

Rich
R Barrell

'78 B. Replaced the heater valve last summer because of leaking. Heater control cable from the dash broke some time ago. Got a new control cable, but haven't hooked it up yet. I currently have the valve mechanism safety-wired in the open position somewhere in the middle of the valve. Looking at the valve, is full heat on with the mechanism turned all the way clockwise? I'm getting some heat, but don't think it's enough.

thanks
Shook

Shook, You will get lots more heat with the gate valve modification detailed on Bob's website. The only inconvenience is you have to open the bonnet to turn the heat off or on.

Clifton
Clifton Gordon

The pukka control valve as supplied from the factory, and OE replacements, is a very nifty piece of kit. It actually is a three-stage valve - the first stage shuts off water flow altogether. The 2nd stage gives a fine control of heat when the valve is partially closed. It does this by way of a tapered needle valve operating in a small orifice, much like an SU needle and jet. Without this the valve tends to be either on or off and is tricky to set to a 'warm' setting. The 3rd stage lifts this needle and jet off a seat and allows a much larger flow of water through the valve for higher heat requirements. With everything else correct you should get plenty of heat from the heater, I've measured 140F at the vents of mine on a 50F day. With nine areas contributing to poor/effective heater performance there is pleny of scope for something else to be wrong instead of or as well as the water control valve.
Paul Hunt 2

I'm sure it's a nifty piece but over-engineered for such a simple car - maybe for a Jag. Sometimes I'd rather have simplicity.

Bob, I think the heater control from a Midget would look a bit more elegant although a lot pricier.
Mike MaGee

Thanks for the kind words, Clifton, I am glad it worked out well for you.

As you probably noticed on my site, it is possible to rig up a direct connection to the temp control cable from the dash, altho it does mean modifying the control handle of the ball valve a bit and creating a bracket to hold the cable in relation to the valve. However, when I did mine I was happy to note that there was more than enough movement of the cable from full off to full on to make the lever on the ball valve go from fully closed to fully open easily and without having to install a different length cable.

As I stated on my site, the cable clamp on my improvised cable bracket came directly from an old OE valve (just drilled out the spot welds and replaced them with steel pop rivets when mounting the clamp to my firewall mounted bracket ~ you could braze the bracket and the old clamp if you chose). Once the cable was held in place, it has worked as smoothly as the original setup.

I know it looks weird to see the bracket not attached to the valve, but frankly, there is not enough engine movement in relation to the firewall where the my cable bracket is mounted to cause any noticable problems in operating the lever. However, I know that not everyone will want to attach a bracket to their firewall. I am sure there are better ways to mount the cable clamp directly to the valve body as in the drawing on my site. I have known of several folks over the years who have come up with their own cable connecting schemes and they report that they too can control their ball valves from the dash. I just wish I got to see more photos of what they have done! ;-)

Bob Muenchausen

Bob, For some reason I missed the last photo with the cable hooked up when I printed out the instructions. I made a bracket today but my control cable is too short and I have to fine tune the bracket. The 74 cable is routed differently than the early cars. The last Moss replacement I bought was too short. I used a generic lawnmower gas cable to make a cable, I wish I would have added a few inches to the length.

Clifton
Clifton Gordon

Sorry it isn't as easy as mine was. Too often I assume that some of these things remained the same throughout the production of these cars, but they haven't. I wish we could find raw cable/housings as stout as what came from the factory. I will have to do a little digging and see if there is a place we can find raw cable heavier duty and better suited than some of those lawnmower/choke cables I have usually seen. Most I have found seem pretty light duty.
Bob Muenchausen

Bob, It wasn't a big problem. Due to the angle of the valve in relation to the cable entry my cable was too short. I used a lawnmower cable and as you mentioned it isn't as heavy as the cable I removed. It's working OK at the present. I had a used heater control that I used as a donor for parts to hook the cable to the ball valve. I'll send some photos showing what I used and my finished installation. Naturally it doesn't look like a factory installation.
It should be great for my needs.

Clifton
Clifton Gordon

The factory changed the heater control cables sometime between 73 and 75. My 73 has a naked spiral wound outer, my 75 a plastic covered, nylon cored outer with four longditudinal steel wires embedded. The inner is solid in both cases. The older one is great for pulling, less so for pushing as the spirals just open up like a spring. I've had to add a helper spring to my valve to help push it off the flat bit when it is fully closed. The later tytpe is good at both pulling and pushing - up to a point. Because the outer is plastic and nylon it deforms more under the clamp and so is held less tightly, and with a stiff valve the outer slides in the clamp. Fortunately it is pulling that is the problem on the V8, and I have been able to control the outer sliding further into the clamp at both ends with some very stiff wire looped round the inner and the clamp.

What is needed is a steel spiral outer with nylon core with four steel wires embedded ...
Paul Hunt 2

You may want to take a run thru this listing of cable makers for Push/Pull cabling:
http://www.thomasnet.com/nsearch.html?cov=NA&what=Controls%3A+Push-Pull&heading=18650200&navsec=prodsearch

There may be a few places which can offer us some better choices for flex control cable.
Bob Muenchausen

talking about heaters, what does the lever do on the left its got a white knob. and what position does what cheeres big ears daz
daz

Daz, that's a fresh air vent. It basically opens the cabin up to the air coming in from the vent in front of the windscreen. To get the heater to do anything you want to close that. I have also heard that you can use it as a kind of recirculating vent. If you have the heater on and block the outside vent with one of those magnetic covers and leave that fresh air vent open the heater will suck air in from the cabin through there (rather than from outside) and then heat it and send it back to the cabin via the footwells.

Simon
Simon Jansen

BTW, I have updated my alternative heater valve page, http://www.cibolas7.net/12272.html, with some more photos from Clifton Gordon, and some additional commentary. FYI
Bob Muenchausen

This thread was discussed between 23/11/2005 and 07/12/2005

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