engine core plug

[stuart]

hi
just found the source of my oil leak, the core plug next to the oil drain rubber tube is missing!
I have 2 spare heads one has a core plug and the other none. I got a new one from QED the question is how do I fit it and can I fit it without removing the head?

[rgh0]

Very hard to fit properly without removing the head. I have tried a couple of times without success. The seating area is normally in fairly poor condition also if the plug has dropped out at some stage which makes fitting a new one even harder.

I have tapped the hole and put in a threaded plug when this occurs to seal it without removing the head. The threads are not formed perfectly as the hole size is only roughly right and a little to big but you get enough thread to seal a threaded plug in OK given that it sees no real pressure.

cheers
Rohan

[billwill]

I think the one you are talking of goes into the oil condensing chamber which is built onto the side of the head. Most core-plugs of course go into the water chamber, so you would very quickly know if one was missing.

So this one is on the underside of the head next to the block?

That chamber connects through the side oil vapour ventilation hole to either the air box or to a drain pipe (on older models) so is not at any significant pressure.

So if you do not want to take the head off at present you could consider rigging somethink like a kettle repair washer on the outside held in place with the kind of spring-loaded wings fitting used to hang pictures on a plasterboard wall.

Then you can fit a proper core plug the next time that you take the head off.


You can't fit it in-situ. It is (usually) a disk of steel that has been domed; if fits (just) in the recess, then you hit it with the domed back-end of a metal-working hammer to flatten it. This expands it into the recess so that it won't come out.

[stuart]

thanks for your replies
today took out the starter and carbs. the new core plug is a tight fit in the recess needing a magnrt to pull it back out. i am going to try and fit it, what sealant should i use? i have some vw/audi silicon for sealing oil sumps will this do? got a long bar to try to expand the plug by hitting from below i can just see it. any other thoughts?

thanks
stuart

[MickG]

Hi Stuart,
Use Wellseal around the plug before fitting

Mick G

[Quart Meg Miles]

Hi Stuart,
Use Wellseal around the plug before fitting

Mick G

That would do as there's no pressure. Loctite 5926 Instant Gasket is an alternative and I've sealed leaking water core plugs with it, lasting for years, or your VW Silicone. Clean oil off the surfaces in all cases.

You can always jack-up the bar and use the car's weight to flatten the plug. Decades ago I fitted a new core plug in the back of the head using a lever and it's not fallen out yet.