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Core plugs
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Rick
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Joined: 27 Apr 2005
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PostPosted: Tue Sep 01, 2009 8:40 pm    Post subject: Core plugs Reply with quote

Just knocked out the remains of the Minor's core plugs in the head, their seating ledges should clean up reasonably well, but is it best to use a dab of sealant or install them dry?? It uses the convex plugs, that you tap the centre of once they're in place, rather than the cupped ones that just tap in.

RJ
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Various 1920s-1960s - Austin, Morris, Commer, Dodge etc.
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47p2



Joined: 24 Nov 2007
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PostPosted: Tue Sep 01, 2009 8:45 pm    Post subject: Reply with quote

Paint the inside face of the core plug and smear some Hermatite around the edge before you tap them into place
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Ghost



Joined: 20 Apr 2009
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PostPosted: Wed Sep 02, 2009 12:48 am    Post subject: Reply with quote

I've always assumed core plugs are to 'give' under extreme pressure as a way of minimising frost damage, fact or fancy? If this is correct then a 'srong' fix is wrong?
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47p2



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PostPosted: Wed Sep 02, 2009 7:19 am    Post subject: Reply with quote

Red non setting Hermatite won't give a strong fix, it will however help seal the edges. I would assume the Minor's radiator doesn't work under pressure anyway so the only time it would ever have been under pressure was when it was frosty. A good quality anti-freeze would prevent this
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Rick
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PostPosted: Wed Sep 02, 2009 7:20 am    Post subject: Reply with quote

would blue Hermatite do the job too? from reading the box it also remains slightly pliable

R
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47p2



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PostPosted: Wed Sep 02, 2009 8:06 am    Post subject: Reply with quote

I've never used bule, but it isn't going to set rock hard so I would say it should be ok
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Austin-sixteen-Cornwall



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PostPosted: Wed Sep 02, 2009 4:34 pm    Post subject: Reply with quote

As far as I am aware the only purpose of core plugs is to fill the hole left after the casting process of the block or head the core sand is removed through the holes. If the block was frozen with water in it I am sure the pressure of the ice would push out the core plugs anyway - sealant or not. But of course you are not going to let your Minor get to that state are you?
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SV8Predator



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PostPosted: Wed Sep 02, 2009 7:20 pm    Post subject: Reply with quote

Austin-sixteen-Cornwall wrote:
As far as I am aware the only purpose of core plugs is to fill the hole left after the casting process of the block or head the core sand is removed through the holes. If the block was frozen with water in it I am sure the pressure of the ice would push out the core plugs anyway - sealant or not. But of course you are not going to let your Minor get to that state are you?


That's quite correct, but the frozen coolant prospect led to them being referred to as 'freeze plugs' in some markets, and in Australia they are referred to as 'Welch Plugs', so explain that one!
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Phil - Nottingham



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PostPosted: Wed Sep 02, 2009 8:10 pm    Post subject: Reply with quote

A frozen block may force the core plugs out - I sold my 1961 Mk6 Reliant Regal in 1975 which had a Reliant Austin 7 side valve engine in - the new owner did not put antifreeze in and it froze solid and pushed out 3 core plugs with tubes of ice like tooth paste behind them. No other damage and engine even started although water-pump was frozen so belt slipped

Do not bank on it though as most block walls are very thin cast iron which breakes quite easily
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exbmc



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PostPosted: Thu Sep 03, 2009 2:40 pm    Post subject: Core plugs. Reply with quote

When I were a lad, it was a common habit to use anti-freeze in winter only. Many people drained it out and used water only, in the "summer" months.
Consequently, the cooling circuit was not as clean as they are these days.
Corrosion caused core plugs to leak, so most of the ones I have fitted were due to rust. It was routine to clean up the plug seat area, and use a rotary wire brush if you could get in. Any sealer you had to hand, "Stag" or "Hylomar" was common, just to aid the seal. Tap the convex ones with a ball pein hammer, or round ended drift like an old push rod, if you couldn't get the hammer in. I have seen only two cars with "lollipops" sticking out the engine, due to frost. One was a minor 1000, the other was a Vanguard 6, which I sold, and the new owner drained out the Bluecol! Unfortunately, the Vanguard cracked it's block too, so was scrapped.
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Scotty



Joined: 23 Nov 2007
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PostPosted: Fri Sep 04, 2009 8:12 am    Post subject: Reply with quote

Although its rare to change core plugs, I've only had to change one in thirty-six years of vehicle ownership, it was a total b........r as it was behind the flywheel!

When I was about to buy the replacement an old gent steeped in classic car ownership suggested that its worth finding out if the plug was available in brass, that way it would be a "fit & forget" forever. Apparently marine versions of vehicle engines are often fitted with brass core plugs as sea water rots steel ones in a heart-beat.

Certainly ones for the Chevy engine are as easily avaliable as steel ones, all I need to do is stipulate which metal I want - food for thought perhaps?
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47p2



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PostPosted: Fri Sep 04, 2009 8:25 am    Post subject: Reply with quote

I remember my father using old pennies to make core plugs Shocked
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Jim.Walker



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PostPosted: Wed Sep 09, 2009 11:13 pm    Post subject: Reply with quote

I have not yet successfully used the "Quote" tab, so I must refer you to the reply by exbmc.

As he says, draining the system used to be the norm in winter. Particularly as heaters were a rare luxury and almost all the water could be drained off overnight.

However I believe the problem is that letting air into the system allowed the oxygen content (in the fresh air) to happily corrode away at the internals (particularly core plugs). The water in a cooling system if undrained for long periods becomes stale and contains little air, so those people who relied on some kind of external heating rather than draining rarely suffered core plug problems.

My Dad had a foolproof way of protecting newly fitted core plugs which he absolutely insisted was used in his repair shop. He always tinned the inner surface and edges of the core plug with solder. The inner coating prevented corrosion and the layer on the edge (being soft) made a very good seal even when the machined edge of the hole was slightly damaged.

Believe me IT WORKS.
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Brian M



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PostPosted: Thu Sep 10, 2009 7:53 am    Post subject: Reply with quote

Another core plug story.

My previous classic was a 1957 Rover P4 60 that had stood for 23 years in a garage when I got it. There was no water in the block, and the visible core plugs on the side of the block had corroded so they were replaced. When I first filled it with water there was a leak from an unseen plug on the back of the block with about one inch clearance to the bulkhead, so my first thought was that the engine would have to come out.

I thought I would take out the gearbox cover inside the car to see if the plug could be reached from there, and found that a previous owner had made two vertical cuts in the bulkhead up from the bell housing. The flap in between could be bent to the horizontal giving perfect access to the core plug.

So what appeared to be a major job was done in under one hour!
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Phil - Nottingham



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PostPosted: Thu Sep 10, 2009 7:29 pm    Post subject: Reply with quote

Rover actually advised cutting a hole in the bulkhead to do this job!
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