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MG MGA - Rear block plug fitting

Help!! The rear block plug failed last week, typically at midnight on the motorway going home after a hard day. I had no torch so thought the head gasket had gone and had to get the car towed home. Under investigation today I see the rear block plug has blown out.
My question is, can it be replaced without removing the engine?

Any suggestions appreciated.

Thanks
Neil
Neil Purves

You Need the Betson Plug. Call Chris Betson or google it

dominic clancy

There are repair plugs made out of rubber. They have a bolt in the center that expands the rubber plug much like a thermos cork. I put one in a ford one time as a temporary fix and it was still in it when I sold the car several years later. Didn't leak a drop.
Ed Bell

I found a photo of a rubber core plug. When you tighten the nut the plug expands inside the block until it is a tight fit.


Ed Bell

Hi Dominic, I found reference to the Betson plug on the MGAGuru site but it says for 5 bearing engines only. I also do not see how it works.
Am wondering if I can get any access if I remove the tunnel cover then use an air punch with a ball and to seat the plug.

The rubber plug looks too big but I have seen other plugs that expand and look up to the task. Just need to find how to get hold of one.

Neil
Neil Purves

Later model MGB engines have a taller rear plate the obstructs access to the rear core plug. The Betson Bolt is a way to install and hold the rear core plug in place without removing the 5-main bearing engine to R&R the rear plate. The Betson Bolt is not needed for the 3-main bearing engine.

Due to restricted access between the firewall and engine block it is near impossible to install a standard rear core plug without pulling the engine forward. Solution is a bolt-in cor plug. The rubber "thermos bottle cork" style may work if the water jacket is deep enough at that point. I happen to like the all metal Dorman plug better. It is secure and permanent and will work in very shallow space. See here: http://mgaguru.com/mgtech/cooling/cool_105a.htm
Barney Gaylord

Niel, In the Tech Sessions MGA BOOK written by Mike Ash he descibes how to replace the core plug with the engine still in place. Best of luck..Clive
c allen

Neil,

About ten years ago I lost the rear core plug and also had to get towed home.

I managed to fit a new one without removing the engine. I did it by making up a sort of screw jack from an internally threaded bar and a bolt. With the new core plug seated by hand I put a piece of wood along the bulkhead as a spreader and screwed up the "jack" to push in the plug centre and make the seal.

At the risk of provoking the gods, it has given no trouble since.


Malcolm
Malcolm Asquith

Neil

By the time this discussion finishes you could have had the engine out, fitted the standard plug, and put it all back in again! Barely an afternoon job for the likes of Dominic; a day and a half for me with plenty of back resting breaks.

Steve
Steve Gyles

I did have to replace a corroded rear core plug once, and imagined t would be faster NOT to take the engine out. By the time I had fiddled with the removable toeboard plate and found a way of getting enough force on the plug to install it without incurring other damage, I would (as Steve says) have been FAR quicker taking the engine out. As there is no need to set the timing and carbs and valves, or even to lift the engine completely out of the car, I reckon this could be done in morning of you have an engine crane.
dominic clancy

This thread was discussed between 02/03/2013 and 03/03/2013

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