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MG MGA - Blown Core Plug

Blown a damn core plug!!
Can I get the engine out and leave gearbox in?

Colin Parkinson

Sure. There is always a debate following such a question as to whether that is better/easier etc. But, yes you can remove the engine with or without the gearbox, no problem.

Try Steve Gyles tip of tying the bonnet back (to the rear bumber if I remember correctly) to save having to remove it.

The next obvious question is which plug and whether or not you can fit the new plug with the engine in the car. I will assume you have already ruled that out!
Neil McGurk

Neil Hi, it is the middle one (on he RH side). New engine build, so I have obvioutsly got it wrong!!

I thought I was confident before, now I am not so sure!

I can get at it, but was thinking along the lines of using cup plugs, as used on the later Gold Seal engines.

Any comments?

Colin Parkinson


If the block was nice and clean then the plugs should fit pretty tight, unless there are some rogue aftermarket parts out there. Where did you get the plugs? Did you make a nice dent in the plug when you fitted them? As usual there is some good information on Barney's site.

Neil McGurk

Neil the plugs came from Moss! I had already seen Barney's tips on fitting them, and I think there was a nice dent.
I do remember when fitting them, I did have a problem with one. I bet it was this one. Took 3 plugs to get it to fit. They kept going 'over centre' if that makes sense, and falling out.

Will have to do some measuring and cleaning.

Incidentally I did use a sealant as well. Cant remember what it is called, but recomemnded by an MG reconditioner. Made in Germany.

Colin Parkinson


Dish type plugs can be a nightmare, try using loctite, also carefully centre pop the area around the core plug, this helps them stay in, they can be strapped in with a metal plate but this look unsightly and the block needs drilling and tapping. I had my race engine block machined to accept cup plug but you will need to strip the block and clean the swarf out afterwards. Is your engine pinking? the shock wave from pinking (detonation) can knock out core plugs.

Terry Drinkwater

Terry, it is actually a race engine, but I had not put straps on this one! Bugger! I have 2 other B engines to do, both of which already have cup plugs in. They will get straps as well.

Pinking? It has only run for 5 mins, not even bedded in the cam yet!!!

Colin Parkinson

Use the exspansion plug mentioned in Barney's site. They work great and you can leave it in untill your next engine pull.
WMR Bill

Are the Dorman expanding plugs mentioned by Barney available in the UK?
Malcolm Asquith

Malcolm - They may be but I sent to USA for some - had to buy 5 even though I only needed one - so I have a couple spare - let me know if you want one - 5 each plus p&p - see club website - For Sale and Toolbox pages - ( Cam
Cam Cunningham

This thread was discussed between 25/03/2009 and 30/03/2009

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