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MG Midget and Sprite Technical - Engine core plugs

Does anyone have a good technique for removing (and eventually replacing, with new of course) engine core plugs?

I was going to get my engine bathed in some sort of obnoxious chemical before rebuilding and would like to do a thorough job by completely stripping the block. The core plugs are the last hurdle!

Thanks all,
Malcolm
Malcolm Le Chevalier

Core plugs are domed, such that when fitting you tap the centre of the dome down a bit and it spreads the edge flange out to grip the recess that they fit into.

I removed mine by hammering an old screwdriver through the middle to relieve the tension, and then levering them out. Try and avoid working around the edges as you may damage the machined edge needed to get a good seal.

When replacing, clean out the edge of the recess. I then put a smear of sealer (I think I just used red Hematite) and put the new plug in position before tapping the centre to get it to seal.

I think Frost will sell you a special tool for removing them, if you enjoy wasting money.
Guy

Exactly as Guy says. when tapping in, be sure to use the flat face of the hammer and not the ball pein, because if you use the ball you won't spread the plug, you'll just put a dent in it and it will eventually come out again. Don't ask how I know this!

Bernie.
b higginson

Just a wee bit confused about why you need to hit them in the middle? The plugs are 'bucket type' rather than 'dish type'. I thought they fit just by interferance fit of the plug sides.

http://www.rimmerbros.co.uk/Item--i-GRID005530

Two types about 3/4 the way down the page.

Cheers,
Malcolm

Might just get the engine shop to do them...
Malcolm Le Chevalier

948 & 1098 engines used the larger domed type.
Dave O'Neill2

My experience is with A series ones, but I think the 1500 ones still work by the same principle. If you look at the illustration carefully, you can see that both the "bucket" and the disc types are still domed
Guy

The bucket type ones fitted to the 1275 are flat, well all the ones I've fitted have been. Sound like the same type as your 1500. To remove the old ones I just hammer a centre punch into the middle and then lever them out. To fit the new ones I use a socket just the right side to fit in the plug and knock them in. I usually put some form of sealant on them as well. I doubt it's necessary though.
John Payne

Alwways use the right tool to insert the "bucket" style of coreplugs

For me the right tool happens to be a Britool socket that fits "just inside" the bucket and gently leaned on, after Red Hermetiting, by a copper headed Brummy screwdriver to seat within the machined recess in the casting

I have a spare core plug hanging around the garage, getting in the way when I'm searching for anything important

It isn't dished though just slightly edge tapered, I know if I ever need it, it's gone missing :)

But to answer the how do you remove it, find the rusted "thin spot" and give it the attention Guy recommends with a sharpish screwdriver or small pry-bar

Then lever its remains out gently avoiding the sharp machined seating edge



All that writing for a one minute job

amazing things cars
Bill1

Bill,

very eloquent though!

Jeremy
Jeremy 3

The new set of plugs arrived in the post yesterday. They don't appear to be dished in the way people describe. They are pretty thick too so would need a good pounding to get them to 'pop flat' if they were.

I will just hammer them in with an appropriate socket and a bit of sealant. Sure it will be fine! :-)

Malcolm
Malcolm Le Chevalier

Sorry to mislead you Malcolm. There are obviously both domed ones and flat ones. Both do the same job though. I think the important bit is to get the seating area clean and then a wipe of semi-hardening sealer such as Hermetite is sufficient.
Guy

No worries Guy, I would have figured it out eventually. Can't get the things out in the first place though. All my levering impliments are a wee bit bendy!

Malcolm
Malcolm Le Chevalier

Maclcolm do you have any threaded rod or a long bolt and nut. You may be able to improvise an extractor of some sort with a large socket.

First drill two holes in the plug these must interesct if you follow my drift.

You have the large hole big enough to fit the bolt head through the plug and the small hole just big enough to clear the thread of the bolt. The idea is to drill the small hole around the centre of the plug so when you get the bolt in place you can use the nut and suitable thick washer against the back of a large socket to tighten up against the plug until it comes free. One difficulty is to stop the bolt from rotating as you tighten the nut up. If its really long you can lock the top with two nuts locked against each other - or use a pair of stilsons or a mole grip.


I hope that makes sense - I can't say i have done it myself - but it should be possible witht he right bits.


Just drilling and tapping the plug probably won't give enough bite to pull it out - but that would obviously be a lot easier to try...
John Barber

This thread was discussed between 10/05/2012 and 11/05/2012

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