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Triumph Repair/core plug corrosion


Hi Howard
I have some corrosion just inside the lip of the Centre core plug right hand side on my Stag.  Don't think model matters much so hopefully you can help me.  The core plug was weeping slightly.  It seems a very thin lip.  Is there some epoxy or metal type wild Devcon or such and would it help to increase the thickness of the lip and stay in. Any advice welcome
Perth Western Australia

Hi Richard,

I have used Devcon and it is very good for a lot of repairs. It is tough and machineable. It would be my first option before an expensive welding job or block replacement. You should also look into the possibility of eletrolisis as a cause and get the additive that diesel engines use to prevent further damage. Another option is a core plug that is a replacement which has a bolt in the center and expands as you tighten it. Possibly in hot rod supplies. Don't remember where I seen them.

This electrolisis can be caused by either the dissimular metals of the engine cooling system and / or poor engine to body grounds. Do this, run the engine at a fast idle and put the (+) positive probe of a volt meter into the coolant and the (-) probe on the negative post of the battery (not the cable end) and set your volt meter on a low volt scale. While running the engine at a fast idle (1500 to 2000 RPM) If you read some voltage put a set of jumper cables on the engine block to the (-) of the battery to see if it lowers the voltage. If so add more ground straps to engine to body and body to negative of the battery to cut down on the voltage of the coolant.


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Howard M. Fitzcharles III


Triumph TR-4 up & Spitfire, and Engine theory


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

Associate member SAE EAA member

Import Car magazine

ASE Master Auto with L-1 certification up to 2000

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