Core plugs

[jagnut66]

Hi,
Is it possible to change the core plugs in the block without removing the engine. I have a slight weep from the back one (above / behind the distributor) but I don't want to take the car off the road to sort this, if possible.....
Many thanks,
Mike.

[philthehill]

It is perfectly possible to replace the core plug above and to the rear of the distributer without having to take out the engine.
Only the core plug at the rear of the engine block requires the engine to be removed for access.
Remove the distributer to give better access - put a plug of cloth down the distributer hole to stop any crud getting into the engine.
I would suggest that whilst doing the one it would be prudent to do the others on that side of the engine.

[edd_barker]

I was advised to dab loctite around rim beneath core plug, and then paint a little over the top to aid sealing, as it is not a machined surface, but rough from casting. I imagine there are all manner of sealants you could use, clear nail varnish is another option!

[jagnut66]

Thanks for the above info.
Any tips as to the best means of extracting the old ones?
Also I assume I should drain the coolant first.
Best wishes,
Mike.

[philthehill]

Drain coolant.
Drill a 5/16" hole in the core plug, insert a long punch into the hole and lever out the core plug.
If the core plug is rotten it may be possible to punch a hole in the core plug instead of drilling.
The surface that the core plug seals against is machined so a good fit can be obtained.
Fit the core plug into the hole convex side out and with the ball of a hammer or similar give the convex centre of the core a good whack(s). This ensures that when the core plug is flattened it increases is diameter and grips the sides of the core plug hole.
There is no need to go overboard with the whack(s).
Some form of sealant may be used around the edge of the core plug.
The core plug in some quarters is referred to as a welch plug.

[jagnut66]

Thanks Phil,
It crossed my mind to punch a hole and lever it out but I thought 'that's too obvious', so decided to ask to be sure.
Sometimes things aren't as complicated as we have a tendency to make them...........................
Thanks also for tip on refitting.
I will probably go with 'loctite' as a sealant (I have some on the shelf and being a tight git...... ), as I imagine I will have to lightly clean the plug hole with sandpaper to remove surface rust once the plug is out.
Best wishes,
Mike.

[palacebear]

To add my twopence-worth. Many years ago, my City & Guilds training included removing core plugs using a small(ish!) cold chisel, and sealing new ones with red Hermatite. As I've never had to remove a core plug since I completed the training, I can't even be confident that red Hermatite is still available....

[philthehill]

http://www.ebay.co.uk/itm/Hermitite-Red ... SwYlRZIK80

or

http://www.ebay.co.uk/itm/Hylomar-Hylot ... SwdzVXjlvh

[palacebear]

Cheers Phil! Answers that question

[jagnut66]

sealing new ones with red Hermatite

Thanks for the info, since it was recommended on a City & Guilds course and is still available at only £14.99 I may well get some.
Best wishes,
Mike.