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MG MGA - Temperature gauge sensor

I am attempting to remove the water gauge temperature sensor from the water elbow on the head of my engine block. What's the solution to it being 'stuck' inside the elbow and elbow being 'stuck' onto the head??

Stephen Lofaro
Simi Valley, CA
58 MGA 1500 Roadster
Stephen Lofaro

Use a real flare but wrench on the fitting, nothing else. You don't want to crush the thin wall tube nut or rake the corners off of it. Cost is about $100 to get it repaired these days. See here:

For removing the thermostat cover, use lots of penetrating oil on the studs, and drive a sharp knife blade under the edge if necessary. See here:
Barney Gaylord


I have removed the thermostat cover. I have also removed the fitting. I cannot remove the sensor from the opening. It seems to be hung up on the seal surface in the threads. Is this supposed to screw out or just pull out? Also, the ferrule has become loose from the back of the sensor. I am concerned now about how delicate this all has become so I have stopped for the time being. I have tried pushing the sensor out from the thermostat opening but I can't get it removed. It has a bit of wiggle to I am just not sure if there is some sort or twisting motion I need to find a slot or what is going on? What do you suggest?
Stephen Lofaro

This will give you an idea of whats inside. There is no slot but they are difficult to get out and sometimes just as hard to get them to seat when putting them in. B

Bob Walker

See attached picture. The seal surface is the inboard chamfer on the small flange. Sometimes if the nut is overtightened the flange may be expanded slightly, then dragging on the port thread. The only way to get it out is to push on the inboard end and wiggle it. Be persistent, and apply more force if necessary. One way or another it will come out. Just hope it doesn't get smashed in the process.

Barney Gaylord


Your notes are very helpful. I will persist with the sensor. This may end up badly, however all else has gone well so far. I had the gauge repaired many years ago by West Valley Instruments which is nearby me in Reseda. So, at worst I have to hope they are still conducting business to repair this if I should need it. Now I am preparing to remove the engine...the power unit if you read the original Workshop Manual. I am going to post another thread for some questions I have on this procedure. Hopefully, you and others from the community can help clear up some things for me in the process. See you on the next thread. I am just wondering why I need to remove the seats and floorboards!?? Wow.

Stephen Lofaro

This thread was discussed between 22/03/2013 and 23/03/2013

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