Replace core plugs. engine 3.4 jaguar 1967

I’m thinking of changing the core plugs. of my jaguar mk2 3.4 (1967) … but first I want to prepare myself with some parts that I may need more than anything some seal … Will you give me some tips for this project? … really getting the engine out just for the core plugs is a thoug… …I’m new to this … I like the world of mechanics and here I am…:grinning:

I’m will like to do it…but
I’m really thinking about it

Mena (usa)

someone who can give me some information


You would need to remove the exhaust manifolds, and carburettors, possibly the starter motor, access is the main issue, actually replacing the core plugs is not a problem so long as you have good enough access to bash them straight in, if they are the cup type I bash one side in and they usually turn and stick out, you can then either pull them out with mole grips or lever them out but to get them started when fitting new ones you need a good straight bang, the disc type are usually removed by bashing a screwdriver through and then levering them out, they are a bit easier to fit as the hole has a step and they go in easily, they expand when you bash the raised centre, you will find that it is far easier using a large club hammer rather than a smaller lighter hammer, you may need to use a socket as a drift to refit, The engine pictured is a later XK engine with cup type core plugs, yours may be different, the very rear small core plug is into an oilway so will not rust! take a look on youtube,

This is from the E-Book on the old site,
“3.3 - Dorman Freeze Plug Replacement ( Paul Saltwick, May 6, 2004 )
The part number is DC-11, 1.75” expanding copper core plug.

Yes, Dorman has a website that lists distributors.

NAPA is one that sells over the Internet.

The plug should be a snug fit in the block and not driven in.
They can be turned down with a driven socket against Emory paper.
If you need to do this for a blown out plug, make another the same
dimension as a spare.

I use epoxy sealant on the edge.

You only turn the nut 2 turns. Directions are on the bag, however
they are often sold in bulk.

You may need to grind down the acorn nut crown on the rear plug
to clear the throttle linkage.

Installed correctly they will hold a 7 psi radiator cap.

Joel adds on Jan. 25th, 2005:

NAPA has them, part #600-4029. Cost is around $4. You can also
buy them off NAPA’s website:"
I’ve used Dorman freeze plugs [ not on a Jag] and a lot easier to get into a tight place with the engine in place.

Thanks …for your help…im planning everything

For this job

Did you fire the engine up yet? How did it run?

No yet… david… because I will like to flush cool sistem first …and change the core plugs…

You could try starting it and maybe it makes sense to remove the engine… maybe it runs great and you know you don’t need to replace anything else!

I am in doubt if the cooling system has residues and if I turn on the engine I can damage the water pump … day ago ijust changed the hoses … but don’t wash the system…:grin: … then I looked at the core plug have little leak signals … when I changed the hoses they didn’t have any residue … but I don’t know how the pump will really be?

If the pump turns it shouldn’t get damaged or you probably need a new one; and if the hoses weren’t completely full with residue (even if) the engine should have no problem idling for a while so you know if the carbs need to be rebuilt or if the oil pressure is dramatically low or if there’s some noises or leaks… in which case you should remove the engine, and in the process it would be easier to attend to the core plugs. You can loosen the belt of the water pump slightly so if anything goes wrong it will slip. But it should turn freely by hand, does it?
What I would do is see if it turns, check the fluids, add fuel and them have a look at how it runs - then flush it with the core plugs removed.

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Should be change the core plug

You obviously have to but I don’t think it would hurt to run it for a minute. Provided it turns and all the valves open and close!

having time I’ll do it … and I’ll write how it went😀
Thanks for you help…and your time… cheers

This is what you could find behind those old core plugs, and then a ton of rusty debris blocking water passages. Dont forget the ones in the cylinder head ! Click on the IMG for the Cyl head core plug. This one was almost rusted through.

Yeccch! That musta taken a miniature jack hammer to clean up!

Don’t scare me please… enough :grin::grinning::grinning:

Can someone tell me how many core plugs in total the 3.4 engine of the jaguar mk2 (67) has …? In some drawings of moss and limora it says that it has 7 of 1 3/4 and one of 1 "that goes in front of the crankshaft … total there are 8 … distributed 3 on the left side and three on the head of the cylinder …! ! and the one who goes in the crankshaft … but on Martin’s page he says that he has two 1 "in the crankshaft … !!! how is that … ??

There are two in the cyl head , visible after the inlet manifold is removed.
There is one at the very rear of the block, just below the cyl.head
There are three on the exhaust side of the block.
There are four on the carburetor side of the block
7 large @ 1 3/4 on block.
1 small @ 1 inch on block
2 small @ 1 inch in head

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in the manual it says it’s 1 3/4 … I don’t know

in the manual it says it’s 1 3/4 … I don’t know…let me see