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Did everything as advised on threads and websites whilst cleaning up a LC head. Two are staying in and one has popped out twice despite re-punching a little flatter (once I found it in the road next to the start of the water patch!)
What is best option just to get rolling again now - just use a bit of JB Weld, or can one get slightly oversize plugs?
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If the bore is ragged is difficult. Discs Hard to make even with lathe, although can be cut out and filed and domed with a pein hammer in a countersunk hole .
Appearance matters with a Seven but various options with cover plates and retaining scew(s)
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On my Ruby I have tapped a thread and screwed in a 6v temperature sender (from an early studebaker new online). Gauge is in farenhight, bonus.
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20-07-2021, 08:13 AM
(This post was last modified: 22-07-2021, 12:22 PM by JonE.)
others have suggested a 1/2 BSP tap, so perhaps that is sensible thankyou - even with a brass plumbers plug.
I just wondered what the water pressure retention was in comparison with silicone/epoxy/jbweld strength? Others had mentioned putting core plugs in with a touch of epoxy anyway.
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Hi Jon,
You did well to find it on the road!
A roadside repair is to knock it in with a thickness of rag all round. It'll probably leak or weep still but may hold water well enough to get you home.
If the hole is worn oversize, oversize plugs are available in 1/32" increments I believe. The perfectionists would have you machining the hole out to suit but carefully filing down the OD and repeatedly trying it in the cleaned up hole, especially if it isn't round anymore, should get you a close fitting plug. I always use Araldite on plugs mainly to corrosion protect the inner face but it does help seal a raggy edge too with a fillet run round the top of the plug. I have seen the edge of the hole popped over with a centre punch to help the retention. The king pin core plugs are more difficult with the pressure from a grease gun.
I hope that helps.
Dave
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If the core plug keeps popping out it's because the hole is out of shape. The hole where the core plug seats was undercut when originally machined. So the hole is slightly larger at the base than at the top; The taper is only a few degrees, but it stops the core plug just popping out without deforming. If you were to go up to the next size, the hole would need to be re-machined, I've done this with badly rusted core plug seatings using an adjustable boring head in my milling machine. But drilling and tapping the hole for a BSP plug would be a good permanent "on the car" repair. Screwfix sell Brass parallel threaded BSP flanged plugs in 1/4, 3/8 & 1/2" BSP at a reasonable price. Using these would be a lot kinder to a relatively thin area of the casting than a tapered BSP bung.
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This is just a thought and not based on experience, but if there is no pressure in the system, why would the plug keep popping out? If the plug has been hammered in place but hasn’t sealed properly would it not just leak? I would have thought hammering the plug would have been sufficient to keep the plug in place even if it did not seal.
Is there a possibility that there is pressure coming from a head gasket leak ?
Like I say just a thought
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Tested with decent caliper today and the Austin 7 stock are 3/4" or 19mm, measuring at 0.745. So I bought some 20mm which seem to be 0.785 - I'm going to try filing one to drop-in size, and dremel an undercut.
