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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Rebuilding Twin Cam MC

Does anyone have experience removing the (seized) piston from a Twin Cam MC? It's been soaking in penetrating oil for a week and still no luck. There is a very slight amount of movement which is encouraging. If there were a way to plug the reservoir feed, it should be easy to use compressed air but we haven't been able to seal it successfully. Anyone have any advice? Perhaps a suction pump?

Mark
Mark J Michalak

Mark,

You should be able to hold your finger over the reserve feed while applying the air. I was able to release one piston with this method. The second piston was not budging. I brought it to our friend John Twist who had three suggestions. You can apply heat to the MC with a torch and then try to blow it out with air, you can attach a grease gun or other hydrolic line to the MC and push it out or you can do what John did. He used a tap to dig into it and then pulled it out. This of course destroyed the pinion but you can buy a quality replacement from Moss for about $10.

Good luck.


Jeff Bennett

The Twin Cam has separate master cylinders for the clutch and brakes, it is not mentioned which one, although the procedures would be the same.
It is likely that the piston would be seized in the fully off (forward) position.
Have you tried tapping the piston further back to loosen it?
I would use a high pressure grease gun, not compressed air. If it comes out with highly compressed air it will travel like a rifle bullet.
Don't damage the piston as Twin Cam pistons are probably much harder to find.

Mick
Mick Anderson

This thread was discussed between 17/02/2008 and 18/02/2008

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