XJ XJ8 / XJR ( X308 ) 1997 - 2003

AJ27 Cylinder Head Gaskets

Old 02-02-2019, 05:11 PM
StagByTriumph's Avatar
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Default AJ27 Cylinder Head Gaskets

I've been doing a bit of checking in the Electronic Parts Catalog and find there is a range of Head Gaskets, a few are superseded, and the superseded are no longer manufactured with no direct replacement.
My North American VIN is ... 1LF23776
My engine number is 0008300515 which, for example, is supposed to use the first two numbers for the LH gasketAJ83707 superseded by
AJ88193 - No Longer Supplied (NLS)
Later engine numbers use ...
NCA2541AC Superseded
NCA2541AD superseded
NCC2541BC Current Stock - SNG Barratt shows this gasket as composite and is not Multi Layer Steel

Multi Layer Steel came off my engine, but the Gasket set JLM20750 from Eurospare and also SNG Barratt use composite gaskets.

So as gaskets are not all created equal, are there any notable issues using the composite gaskets on an AJ27 NON supercharged engine?
It is not like my wife is going to be driving this engine at 168mph for hours on end ... The composite gaskets I have are steel core with composite on either side, and neoprene sealant around the critical coolant /oil passages. Are there really any issues or significant differences?

As an issue, I read the XK8-XKR-x100 thread and "test point" says you can use Lincoln gaskets on an AJ27- which conflicts our gurus that say you CANNOT use Lincoln gaskets because they don't fit ...

That link says XKRacer uses MLS from a 4.2 on his tweaked engine which I can completely understand as it is probably running higher octane racing fuels or is SC'ed, or both.
I recall the x308 gurus also recommend using the 4.2 gaskets - are those MLS on the AJ27.

Good news is my new local Jaguar dealer is actually my old relocated Land Rover dealer where I have a shop discount and they transferred my shop discount over to the new JLR dealer when they took over the previous local Jaguar Dealership.

Actual experience replies on cylinder head gasket issues greatly appreciated!

Old 02-02-2019, 09:44 PM
M. Stojanovic's Avatar
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The MLS gaskets have some advantages but require almost perfectly flat block deck and head surfaces and the surface finish of some 8-15 RA (glass has 3-4 RA). If you are not going to machine the block and head surfaces as required for MLS, just put in the composite gaskets because they, especially their flame rings, comply much better to any small "out of flat" or irregularities on the block and head surfaces. I used NCC2541BC, genuine, not the much cheaper aftermarket replacement.

I did try Cometic MLS gasket on my race car (BMW E30 M3) and it leaked from the start, not much (not to overheating) but I always had a small amount of coolant being pushed out due to tiny gasket leaks. A friend of mine, also racing an M3, tried MLS gasket and re-did it a few times (making sure that the block-head surfaces were perfect) and it still leaked. Both of us, after the MLS experiments, went back to the original composite gaskets and have no issues at all (and this is on race engines, most of the time at 7-8,000 rpm during races).
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