Loose-fitting core plug.

WarrenL

WarrenL

Active Member
I am replacing the core plugs in the inlet manifold on the mounting for the carburettors. There was always a bit of seepage from the top one. The new ones arrived from JR Wadhams and the top one went in firmly using a nice big socket and a few firm taps. However the one at the rear is a little loose.

I think somebody told me that you can slightly expand the diameter of a core plug by tapping its bottom with a ball peen hammer, but I wanted to check the experts around here. I thought that that might work if the plug had a slightly domed bottom, but this one is quite flat. Does the theory hold?
 
Hello Warren,

I would be inclined to think that with a flat core plug, tapping with a ball peen hammer would have the opposite to the required outcome.

Are you using some form of sealant around the edges prior to fitment, ie....Hylomar, Permatex #3 etc?

If it were me, I would be unhappy with a loose fitting core plug, and I would obtain another. See if your local Land Rover spare parts centre has one.

Ron.
 
If these are cup shaped core plugs, then I managed to expand some recently by hammering a slightly oversize socket into the cup side of the plug, obviously the socket ends up stuck inside the plug so you need to tap it off the socket. This worked well for me.
 
SydneyRoverP6B said:
I would be inclined to think that with a flat core plug, tapping with a ball peen hammer would have the opposite to the required outcome.
Click to expand...

That's what I thought too, Ron. However I have nothing to lose at this point so I'll give Richard's method a go. We're probably talking about a fraction of a millimetre - the plug almost fits tight, but giving it a tap moves it slightly. Enough to make me lose confidence in it!

Should Hylomar (or similar) be used as a matter of course around core plugs?
 
WarrenL wrote,...
Should Hylomar (or similar) be used as a matter of course around core plugs?
Click to expand...

Hello Warren,

I know at the Range Rover centre that I frequent, they certainly apply a sealant around the core plugs when being fitted into the Rover V8 block.

Given that the plugs are there only to prevent the manifold or block from splitting should the coolant freeze by popping out, I don't really think that sealant is going to prevent this from happening. Rather I see it as insurance against the possibilty of leaks... :evil: The mating surfaces would need to be perfect, if not you can guarantee you will have a leak.

Ron.
 
Well Ron, the story ended differently. I went down to the local auto spares store and spent a bit of time comparing 1 1/2 inch core plugs and confirmed my suspicion: not all 1 1/2 inch core plugs are created equal. I found one that was a little bigger than my one, took it home, and presto! A bit of Hylomar and a very nice firm fit, thank you.

All's well that ended well.
 
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