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+--- Thread: Core plug seat corrosion (/showthread.php?tid=9819)
Core plug seat corrosion - Lowbarn - 27-01-2025
Does anyone know the best way to seal a core plug which has a corroded seat?
RE: Core plug seat corrosion - Reckless Rat - 27-01-2025
Being a time served bodger, I would clean out the remnants of the old core plug, clean up the top surface of the casting and araldite a metal disc to the cleaned up face. The cooling system isn't pressurised so it should be fine thereafter.
This is assuming that it's a "cooking" engine and not something likely to be presented to the National Association of Rivet Counters.
Yours sincerely
Scrooge Mc Duck.
RE: Core plug seat corrosion - Chris KC - 27-01-2025
If you can install a new plug without it disappearing down the hole I imagine it would seal adequately on its OD.
Failing that I'd be inclined to thread a new plug into the hole, possibly dispensing with the horizontal flange; though I have not heard of this being done I can't see why it wouldn't work.
RE: Core plug seat corrosion - Howard Wright - 27-01-2025
+1 for tapping and threaded plug. Unfortunately I think the core plug hole is slightly bigger than the hole at the top of the king pin otherwise you could have used a brass king pin plug.
Cheers
Howard
RE: Core plug seat corrosion - Robert Leigh - 27-01-2025
It looks as though this is not an A7 core plug problem. The threaded plug idea seems sensible. Flanged brass BSP threaded plugs may be available in a suitable size, and if so a tap will also be easy to get. Try heating and plumbing merchants.
RE: Core plug seat corrosion - andrew34ruby - 27-01-2025
On the bench, put 2 welch plugs back to back. Drill a hole through the centre of both. Drill one out to a clearance fit for a small bolt, and tap a thread in the other hole of the other plug.
Put the assembled 2 plugs into the hole in the engine and gently tighten the small bolt. As they flatten, the 2 plugs should work as intended.
RE: Core plug seat corrosion - Dave Mann - 27-01-2025
I had a similar problem and I tapped the hole I think 1/2" BSP and fitted a screwed plug fitted with a zinc sacrificial anode.
RE: Core plug seat corrosion - Lowbarn - 28-01-2025
Many thanks for all the advice.
I have fitted two new core plugs so far. I despatched my father to pick some up from Jamie at the seven workshop. The new plugs seem to fit, but for whatever reason I cannot get them to fully seal.
I favour employing bodgit and scarper ltd, along with a new tube of araldite as the next attempt.
If that doesn’t work it should relatively easy to grind it all off and then try the threaded hole / bolt approach.
My initial plan was to replace all three core plugs on top of the head, but given my lack of prowess at fitting the things I might leave well alone!
Since the engine is more of an air fryer than cooker ( I get lots of insect splats on the rear screen and none on the front) I don’t expect any issues.
Apart from the lack of steering out of roundabouts, the Austin is really running well at the moment, so I’m loathe to fiddle too much.