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The coldest winter day in 40 years, I jumped into my old mini, standing in the street, no start. Lifted the bonnet, the core plugs standing out of the block on two inches of ice. Waited for thaw, picked up core plugs from road. Hammered back into block, Started engine, ran for another 5 years before the crank broke. The A series engine, a masterpiece of engineering.

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It is along time since I replaced either but it was surprisingly easy though I did need two attempts with a disc type.

cup/bucket or disc/welch plug type they do the same job which is to fill the hole.

dig out the remains if the old one

clean off the rough debris on the the cast surface.For the cup type a smear of lubricant helps when the cup is drifted in use apppriate size drift - a socket is useful.

the disc type is fitted dome upwards then a single strike from a ball pein hammer should spread it to fix it .Don't keep giving it one more tap " to be sure" or it will distort it and leak....OK buy a few.


If they save a head or block from frost damage that has to be good thing- in the US they use the term" frost plugs"but this is just fortuitous as the holes are there as a result of the need to remove the sand during the casting process.

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I've done a lot of these over the years and always install with a smear of Hylomar Universal Blue Gasket & Jointing Compound Sealant with 100% success.


I don't think they will save a block from frost damage in all circumstances. We had an International tractor who's block cracked when frozen but all core plugs remained in place.



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As a matter of interest, why are you thinking of going from dished to cups?


I'd be a little dubious that the block borings done for dishes would be exactly the same as for cups and as the latter are only held in by a tight interference fit you might be storing up problems. But I might be wrong.

And as someone who refitted the three cups on the manifold side of an 1147 just this weekend, all the dismantling required to access them and then get the straight perpendicular strike needed to drive the new cups in right, make it a job I'm not in a hurry to repeat..


As for removing them, as Pete says. In my case, the front end weeping one was so corroded that driving it through with an old strong screwdriver and levering was as easy as opening a beer bottle.


Seeing the state of it and having done the dismantling, it made sense to do the other two. On the rear, driving through was tougher, and levering just tore the centre without shifting the rim.

I ended up piercing all the way around the flat to pull away the centre, grabbing with pincers and levering. The whole centre pulled off leaving just the rim still firmly lodged. Duh. Attempting to collapse the rim failed.


Luckily the pincers were just of a size that I could get one blade through the hole and lodge it against the back edge of the plug enough to lever it out with the other blade against the block, if that makes sense..

The centre plug resisted three hard strikes with the screwdriver without even denting, so Im taking a gamble its pretty sound and left it alone.


I too would love to know if theres a better method. I'm sure a specialist tool could be bought/made but hardly seems worthwhile for such an occasional job. Ingenuity and some brute force seem the way to go.

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I know its cheap, but is mild steel the only suitable material for these things?

The original dished type marketed as a Welch plug was said to have originated when a Mr Welch hammered in a coin of suitable diameter in the early 1900s as a road side repair when a tapped plug came out of the engine of whatever early motir he was driving.

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Generally they will lever out with a piercing and a decent driver or lever to extract,

ive seen big self tappers, and on a real pig welded a nut on and used socket and bolt as a drag


Should Doug get the prize fill with water and let jack frost do the work !!!! Hmmmm.


dont remember but some locations may need to be a welch plug like cam bore where the end plates

must fit flush and not fouled by a risk of a protruding bucket plug


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I have a MK1 2L Vitesse and thought the dished and bucket core plugs where not interchangable. The dished ones needing a ledge to butt up to the bucket ones just knocked in, although if the diameters are the same the bucket ones would only go in so far as the ledge.

Have fitted both types, never sure how hard to hit the dished ones, have seen 2L engines with buckets on one side and dished on the other.





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