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MG MGB Technical - Oil pressure / water temp gauge

Is there any way to replace hollow bolt that fix bulb at the end of capillary pipe (it threads in to cylinder head)? Mine is almost round and is very difficult to uptight and tight it again. I am not shore but think that is this capillary system with wax so if I cut or open capillary tube gauge won’t work anymore.

Toni Kavcic

No - the only way to remove / replace the fitting is to unsolder the bulb.

I suggest that you file two flats opposite each other to fit a 9/16 spanner.
Chris at Octarine Services

"unsolder the bulb"

Wont that lose the fluid and the gauge won't work any more?

If it's moving then do as Chris says, but if it's jammed in you might as well attack with grips first as filing it to fit a smaller spanner will probably round off those flats as well.
paulh4

Is there any way to replace hollow bolt that fix bulb at the end of capillary pipe (it threads in to cylinder head)? Mine is almost round and is very difficult to uptight and tight it again. I am not shore but think that is this capillary system with wax so if I cut or open capillary tube gauge won’t work anymore.

Toni Kavcic

No - the only way to remove / replace the fitting is to unsolder the bulb.

I suggest that you file two flats opposite each other to fit a 9/16 spanner.
Chris at Octarine Services

"unsolder the bulb"

Wont that lose the fluid and the gauge won't work any more?

If it's moving then do as Chris says, but if it's jammed in you might as well attack with grips first as filing it to fit a smaller spanner will probably round off those flats as well.
paulh4

Just a thought when you get the "bulb" out. File it as near round as you can get, the same diameter as the thread and drill out a nut to just slide over the thread. Slit a length of 8 or 10 mm copper "microbore" tube, put it over the capillary tube to protect it and tack the new nut to the hollow screw.
Allan Reeling

Too much fiddling about and you will probably break the capillary tube and lose the fluid anyway. Bite the bullet and get it refurbished , or buy a new one.
Before reinstalling, chase the threads in the head to ensure they are as good as possible, and put some anti-seize on the nut before you install it. Then hopefully you will be able to remove it safely in future.
John Minchin

This thread was discussed between 10/04/2017 and 20/04/2017

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