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Cylinder block core plugs

Posted: Mon Dec 03, 2018 7:58 pm
by Alpine Daimler
Hello
Another winter project beckons namely cylinder heads removal and overhaul.

Once removed I believe (and hope!) that I will have good access to the cylinder block core plugs which I intend to remove to enable removal of accumalated debris from manufacture (!) and deposits which could be causing slight warming up in traffic etc.

Anyway, anybody here know the number and sizes of the plugs? In the Manners site its not stated and they offer 4 different ones.

Thanks

Rob c.

Re: Cylinder block core plugs

Posted: Mon Dec 03, 2018 10:55 pm
by Vortex O'Plinth
It may be easiest to buy an engine core plug set - here for example. This contains six plugs for the sides of the block, two for the front, two for the rear and one at the end of the camshaft. It also includes four plugs for the heads.

Re: Cylinder block core plugs

Posted: Tue Dec 04, 2018 3:34 pm
by migray
David Manners is advertising a set of core plugs on the back of this month's Driving Member for £12.72 inc VAT

Re: Cylinder block core plugs

Posted: Wed Dec 05, 2018 3:05 am
by tjt77
Ive used the core plug set sold by david manners on several engines.. all good in quality and fit....

Re: Cylinder block core plugs

Posted: Thu Dec 06, 2018 8:30 pm
by Alpine Daimler
Thank you for the excellent tips.

A couple of last questions, the best methods of removal (hammer and screwdriver, tip over and extract?) and fitting (tap in squarely with piece of soft wood or mallet?) and sealant? "Core plug sealant" or can another product be reccomended?

Regards
Rob c.

Re: Cylinder block core plugs

Posted: Thu Dec 06, 2018 9:07 pm
by classiclife
Hello Rob,

Dealing with other engines I have usually removed the core plugs by punching a hole in them and levering out; there are not a lot of (if any) alternatives due to their tight fit - ideally you do not want to lever them out from the rim edge as this may cause damage to the block.

Reinstalling the plugs is, as you say, a case of ensuring they are square to the hole and tap them in gently ensuring they go in flush.

A smear of Instant Gasket (or similar) around the core plug edges will ensure a water tight seal.

As with any of these jobs, preparation is everything therefore it is important to ensure the holes the core plugs are going to fill are cleared of any muck, rust and high spots - all of which will do their best to thwart your job !!

Good luck.

Richard.

Re: Cylinder block core plugs

Posted: Thu Dec 06, 2018 10:34 pm
by Vortex O'Plinth
I wouldn't bother with the 'tap in squarely with piece of soft wood or mallet' option. They need a good heavy thump with something hard. A piece of steel or aluminium stock bar just smaller than the plug as a drift and a large hammer are ideal. In the absence of the correctly sized drift an appropriately sized inverted socket can sometimes be pressed into service. Try to spread the plug with a single heavy blow from the hammer. Repeated blows are more likely to lead to leakage in the future. I usually seat mine in Loctite 620.

Re: Cylinder block core plugs

Posted: Fri Dec 07, 2018 8:08 am
by classiclife
Thanks Nick, you are correct.

I think I was being a bit too gentle in my description !!

The inverted socket is an excellent alternative and one I overlooked to mention.

Best wishes.

Richard.

Re: Cylinder block core plugs

Posted: Fri Dec 07, 2018 12:35 pm
by simonp
These engines/blocks are well know for holding large quantities of silt/crud including the original casting material. Most effective way is to thoroughly clean out the block with engine stripped. See how you go. I know Christian Demler leaves the block in a tank for several days and ends up with a bucket or two of crud. Once this is removed I think it is unlikely the car will ever overheat again!

Recently I had a problem with the radiator silting up and that was solved by just having a relatively cheap recore.

SimonP

Re: Cylinder block core plugs

Posted: Fri Dec 07, 2018 4:19 pm
by tjt77
core plug removal;- drill a hole on the middle ...screw in a sheet metal (aka 'self tapping') screw and either use a slide hammer or suitable lever(such as a carpenters nail removing pry bar) to break the plug loose then pull it out..
the critical issue is same as any other engine rebuild practice..cleanliness.. make sure the hole the car plug sits in a clean and free of corrosion ..a suitable sized rotary wire brush will get most of the crud out..you can use sharp tool to get into the edge where core plug seats .. as for sealant ..I personally uses 'permatex ultra grey' which is a silicone base gasket sealer..and I use it sparingly, to give an even coat just inside the step whee the replacemet plug sits and seals against.. to expand and set the plug ..I use 2 hammers..or you can use hammer and suitably sized brass drift..one about 1/2 to 3/4 size of the plug.. place against the plug..and hit with another hammer to flatten the convex part sufficiently to expand the outer sealing edge ,then wipe away any excess sealant.. job done.