Removing man oil gallery plug from block


I am back working to stripping my engine. Nearly there now but I want to remove the large plug on the rear face of the engine block that plugs the main oil gallery. It has a 5/8” female hex form in it to enable an Allen hex drive to fit. my concern is, how much torque is needed to remove it? I only have a 5/8” hex drive with a 3/8” drive and am concerned it will not be beefy enough and I ‘ll end up shearing the drive?
Has anyone here got experience in removing it?
Also, has anyone removed and refitted the various core/freeze plugs from the block and heads?
Any advise would be good.


Good question ? I am trying to do the same thing on my 4.2 liter motor.
Either way, if I can’t do it I will leave it to the machine shop to remove it. I also am having the same experience as you

Regarding removing the freeze plugs. I used a blunt 1/2" cold chisel and strikes just one side of the plug. ( not the lip) This strike would push or collapse one edge of the freeze plug into the block while the other edge would swivel or pivot out. You then just use pliers to pull it out like a bad tooth. There are many examples on You tube showing this method. Worked like a charm.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #3

You need to find a coupling nut, which is a nut used to connect two lengths of threaded rod. They’re just like any other nut except twice as tall. You need to find one with a 5/8" hex, which I’d guess is about a 3/8" thread size. Insert the nut into the hex hole in the plug and put a 5/8" box end on it.

(Mark Eaton) #4

Pretty sure I used an “impact driver” hex driver. Blackened. 1/2" drive. Big breaker bar. Like the following photo (which doesn’t look to scale!)image Not sure it would have come out with a 3/8" drive.


That looks like a better bet! Off to search eBay for one now. Thanks

(Aristides Balanos) #6

There is a similar plug on the oil filter assembly.
Even though it was leaking badly it was impossible to get it loose.
It had some sort of very hard thread locker/sealer.
Heating it with a propane torch did the trick.



I took the plunge today and fitted my 5/8 Allen hex socket into the oil gallery plug and clipped my 3/8 drive ratchet on, slid an 18” long length of pipe over it’s handle and used the pipe to add leverage to the ratchet. Gave it a hefty tug and the plug loosen with almost no effort! And I actually used my hand to run it out of the threaded hole with no effort at all…couldn’t believe it. The only seal was the copper washer. There did not appear to be sealant applied to the thread.
All good👍

(Mark Eaton) #8

For the record, I checked the socket I used and it was a 16mm hex head (into 1/2" breaker bar). It was slightly loose at 16mm in the plug, so I suspect 5/8" (15.875mm) might be quite a loose fit if the plug were really tight.