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MG TD TF 1500 - Moss Motometer

Help guys!
I got a Moss motometer for my 1950 MGTD that does not have a water temp guage. I figured, neat idea. Got it mounted on the radiator cap and fired up the car and .... nothing on the motometer. I looked closely at the water level and the probe that fits down into the radiator and it apppears to be quite short and not hitting the radiator coolant. The only way I can get it to register is to overfill the radiator and then it works for a short time until the radiator goes back to its correct level. It is an original radiator and has never been modified. So what do I do? Is there a way to extend the probe on the motometer with heavy duty copper wire soldered on the probe? I suspect the original motometers had much longer probes, but I could be wrong.
Thanks as usual.
Rob
Rob Silverman

Love to hear the answer Rob. I did the same with the same results. Looks neet, but totally non-functional. Fortunately I found a green smiths temp guage (perfect match for the oil and amp guage) that I installed to the left of the steering wheel. A bit un original, but I like knowing what temp I am running at.

For those in the know, was there a factory option for a temp guage on the early TD and if so, where was it normally mounted?
Bruce Cunha

Rob,
The Motometer you have will work just fine. I have one on my MG and also on my two model T's. They measure the water vapor temperature and do not need to be in the water itself. Do a search for Boyce Motometer and you will find the history about them. The Motometer on my MG went bad so I bought one from one of the Model T suppliers for about half the cost of the ones from Moss and just switched the Model T label for the MG label from the old motometer. They appear to all be made by the same company.
Ken Schroeder

Rob, my observations and experience are not in agreement with Ken. My TD (10855) was just a few weeks too old to have received the dual gauge. However, the gauges are available, the upper radiator tank has the fitting for the bulb, and installation is fairly easy. The only way that you could trust a Motometer to tell you the truth is to keep the bulb immersed in the coolant. Here's one way
http://home.earthlink.net/~budkrueger/Overflow_tank.html
Bud Krueger

I had the same problem. I solved mine by adding a short length of copper pipe to the probe. You just need to crimp slightly.
The length will vary from car to car. Works like a charm.
Bob Wrenn

Thanks for all your responses. I am glad to see that I am not the only one experiencing this problem. I think I will add-on a coolant recovery tank, I like the idea. Why does Moss sell a motometer that is obviously not going to work on our cars. I talked last night to another person with a TD and a motometer from Moss bought 3 years ago with the same length probe. IMHO it is a faulty design and should be rectified especially with the price of these things.
Cheers, Rob
Rob Silverman

When I installed one in my 51, I found the same problem.I found an old single AA battery penlight had the same threads as on the bottom of the Meter. It was about 3 inches long, I just screwed it on and it worked fine.

George
George Merson

I've had the same marginally useful Moss Motometer for years, but this discussion inspired me to take another look and suggest a possible solution. The brass thermowell that extends below the radiator cap and locking nut is approximately 1" long. The top 1/2" of the exposed thermowell appears to be threaded 7/16 x 20 (NF). The bottom 1/2" of the thermowell is of slightly smaller diameter and unthreaded.

Why not use brass round stock of appropriate diameter and length, tap this piece 7/16 x 20 and screw it onto the base of the thermowell? The extended length should take the thermowell to just above the fins in the radiator.

Anybody have some suitable brass stock?

Larry
Larry Shoer

I fabricated the solid brass extension I described. With three feet of newly fallen snow the test was run on the kitchen stove with a pot of boiling water. The Motometer worked well responding to water that covered only the bottom one inch of the new three inch brass extension.

Details:
Fabricated from a piece of 3/4" round brass stock. Length: 2.95"
Depth of hole in center: 1.5"
Hole tapped: 7/16" x 20 (NF)
Cork washer fabricated to fit over existing Motometer threaded thermowell and provided thermal isolation of new brass piece from radiator cap.

I removed the brass nut and washer that secured the Motometer to the radiator cap. The new cork washer was placed over the thermowell, then the new brass piece was snugged on finger tight. When the finished assembly was installed on the TD the bottom of the new brass piece rested perhaps 1/8" above the internal radiator assembly.

The only possible disadvantage of this modification is that the thermal mass of the Motometer is increased considerably. This means that temperature response will be slower, but I don't see that this will be a problem. The Motometer is, afterall, only a very approximate indicator.

Larry
Larry Shoer

This thread was discussed between 11/01/2005 and 27/01/2005

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