Emergency Core plug

[Mark Dymond]

Must have dropped the core plug on the way to the hardware. No one answering the phone at home so made a new one out of duct tape! Worked a treat but I think a more permanent solution is prudent. Is this doable without taking the radiator and generator off. Tips welcome.

   

["Slack Alice" Simon]

You have to take the generator/dynamo off to do the job properly.

If you are lucky, a previous owner has cut a screwdriver slot in the head of the long bolt nearest the dynamo and the block.

Otherwise, it can be a bit of a pain to get out. 

Clean the seating area of the core plug in the block.

If you look at the core plug, it has a sharpish edge where it meets the seating in the block.

So the inner corner of the seating, ideally, needs to be really clean.

So when you hammer the middle of the core plug just hard enough to dent it in, the plug spreads a little, the sharp lower edge digs in, and the seal is made.

Use a bit of sealant if you like.

You will almost certainly have to set the ignition timing again.

[squeak]

Coincidentally I am in the exact same position having tried once to knock in a core plug, failed due to the obstruction of the dynamo, made a foam plug wedged between the aluminium and block to hold back the failed plug. Worked for 50 miles and now leaks again. I have stripped off the bonnet, radiator and shell and in the morning will mark distributor position and remove dynamo. This is complicated by the new copper oil filter lines passing  OVER the dynamo on route to the new pressure crank. I will also scrounge for the largest welsh plug I can buy to fit the hole, and give it one central heavy hit. What type of sealant here is advised?
 Other blocks here have a screwed in welsh plug which seems like a good idea, so far I have been unsuccessful in removing one. I intend to mix up a brew fifty fifty acetone and ATF and try again. 
I too will be interested in the collective wisdom on this thread.

[dickie65]

Yes you can replace that plug in situ. But you need to be careful not to damage the dynamo housing.
I will not describe how I did it in case it goes wrong and causes damage for you. Gasket Goo is useful.
My replaced one has been in for a couple of years now.
I had to replace that one on the roadside when one fell out I always carry a spare coreplugs Hammer drifts etc in the car.

[David Cochrane]

Other blocks here have a screwed in welsh plug which seems like a good idea, so far I have been unsuccessful in removing one.

Hi - Welch plugs are the knock-in type. Do not try to remove the screw-in type as you will probably damage something!

[wild_willy]

Coincidentally I am in the exact same position having tried once to knock in a core plug, failed due to the obstruction of the dynamo, made a foam plug wedged between the aluminium and block to hold back the failed plug. Worked for 50 miles and now leaks again. I have stripped off the bonnet, radiator and shell and in the morning will mark distributor position and remove dynamo. This is complicated by the new copper oil filter lines passing  OVER the dynamo on route to the new pressure crank. I will also scrounge for the largest welsh plug I can buy to fit the hole, and give it one central heavy hit. What type of sealant here is advised?
 Other blocks here have a screwed in welsh plug which seems like a good idea, so far I have been unsuccessful in removing one. I intend to mix up a brew fifty fifty acetone and ATF and try again. 
I too will be interested in the collective wisdom on this thread.

Hi Russell
I use a socket approx 3/4 of the diameter of the plug to seat. This seems to spread the outer edge of the plug evenly to make a nice fit.  Stag paste available from plumbers supply or hardware I found to be a good sealant. It is also petrol friendly  and good for those weepy petrol unions on carbys/fuel tanks etc. without having to overtighten.  Hope you got the diff sorted.
Bruce

[Colin Morgan]

In the olden days, a penny would fit - and was sometimes used, as core plugs cost 2d. So I fitted a 1917 penny, which I replaced a few years later when it started to corrode and weep a bit round the edges.

(Told this by Cecil across the road in around 1995. He had maintained cars at a garage during and just after the the war - also said they used to cut piston rings from cast iron drain pipes.)

[Mark Dymond]

That does not sound too dire, if I dont have to remove the radiator Ill be happy.  Socket 3/4 of the diameter of the plug sounds like the tip I need.

[David Cochrane]

I had a worn core plug'ole in the cylinder head while on holiday in Norfolk a few years ago, so the standard core plugs wouldn't fit. I managed to fix it with a filed down (new) penny.

[Tony Griffiths]

On the cylinder head, I tried three approaches:
1) a standard core plug inserted with a trace of Araldite around it. - seems to be OK.
2) core plug turned up from a bronze bar 0.003" oversize. Plug left in the freezer overnight and engine warmed up before fitting. It went in with a tap from a hammer (OK, I made three, all a few tho different to ensure one would fit). No sealant was used, and that seems to be OK as well.
3) turned up another that needed just a tap with a hammer plus Araldite. That was the quickest and easiest job and worked as well.
The advantage of the bronze ones? They'll survive without rusting away.