I am replacing the the thermostat in my 1995 4.0l. The one I took off is rather large and used a regular gasket. I bought a new one large size as well [180] and it came with an o-ring not a gasket. The part suppliers and shop manual shows an o-ring not a gasket but the o-ring will not work and the gasket is metal not fiber. I am really quite confused. Ideas? Thanks, Steve
I believe it’s Part #NBB2217AC
JDHT is flat out wrong here. I believe you’ll find it when you look up the x300 model with the 4.0 AJ16 engine.
I can confirm the o-ring is not needed with your car.
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What is the part number for?
The 'O’ring is for the AJ6 engine ONLY!!!
DO NOT USE THE 'O’ring for the AJ16 engines!!!
Use the gasket.
The gasket you need for your thermostat.
Thanks. I am going to the dealer today with all the parts I have to get the right stuff.
Interesting they went that direction. Nowadays you typically see newer designs using O-rings where older designs used gaskets. I guess there must have been some issues with the O-rings on the AJ6.
For clarity: Is the thermostat the same for the AJ6 and the AJ16?
I just went to the Dealership with all my parts and talked to the shop foreman who has been with jaguar for well over 30 years. Here are his comments:
- the 12 cyl.thermostat is smaller and looks completely different from the 6 cyl one. The 12 cyl. looks like a typical small block Chevy t-stat
- The stock rating for the is 190 but here in the south with hot summers they use 180 degrees. You must run a thermostat so that the efi system goes into closed loop which on Bosch is about 180 degrees.
- The v-12 has always used a gasket as far as he could remember. The 6 cyl went fro a gasket early on. then to an o-ring which changed to a gasket with a raised ridge embossed in it which was somewhere around 1994 and these use no o-ring.
remember this is from memory,so there might be some date differences.
Hopes this helps. This was a complicated search. Steve
Kirbert Author of the Book, former owner of an '83 XJ-S H.E.
February 21
motorcarman:
The 'O’ring is for the AJ6 engine ONLY!!!
DO NOT USE THE 'O’ring for the AJ16 engines!!!
Interesting they went that direction. Nowadays you typically see newer designs using O-rings where older designs used gaskets. I guess there must have been some issues with the O-rings on the AJ6.
I’m new to this stuff, so I don’t know what these a’s mean.
The thermostat HOUSINGS are different from the AJ6 to the AJ16.
There is no groove for the 'O’ring in the AJ16 housing so the EARS will break if you try to tighten the cover with the 'O’ring in place.
(I have several broken covers in a box from customers that tried it!)
The thermostats themselves are the same part number for the AJ6 and AJ16.
The ‘after-market’ parts manufacturers seem to include the 'O’ring for the thermostat regardless of the application and people remove the gasket and try to install the 'o’ring in the AJ16 engine only to discover that the gap is too large with it and snap one (or both) ear(s) off the aluminum cover when the bolts are tightened.
The parts catalogue lists the housings as (AJ6) ‘O’ ring sealing or (AJ16) Gasket sealing.
If you buy the thermostat from the dealer, you will get JUST the thermostat and then you must buy the 'O’ring OR gasket and the parts guy will ask you for the MY or VIN so you will get EITHER the gasket OR the 'O’ring.
I have successfully welded the broken ear back onto a cover for a customer but I have a TIG welder and I do NOT recommend using the repaired cover for long term use. It will get you by until a good-used or new replacement can be located.
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From afar am a bit of a guess. If the mating surface does not have a groove, the O ring is not intended /
Gasket: if paper, just cut one. from gasket material
If all else not feasible, just use RTV. Did that on My IHC 304 Scout II. Stacked iron parts a mess to get aligned with gasket. RTV to the rescue, worked just great.
Carl
Gee, I would hope the OEM gasket is a gortex sandwich.
I believe all of the XJS engines are specified with an o-ring.
It’s the x300s that specify the gasket…which I believe IS a gortex sandwich.
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The JEPC lists BOTH Housings for the 4.0 XJS.
Assembly - gasket sealing To Engine (142215) NBB2251AA (superseded)
Assembly - O ring sealing EAC6140 (superseded)
@SteveRinaldo,
The AJ6 refers to a 4.0 L 6 cyl engine that jaguar used. It was a newer engine is tends to be very reliable.
The AJ16 is the designation for an improved version (or at least updated version) of the AJ6 engine. It is also a 4.0L 6 cycl engine, and was used in (at least) the '94, '95 and '96 XJS engines.
If it is a change between an O-ring and a gasket, then I would expect there to be a change in both sides of the interface. It is OK to say that partA has been superseded by partB during the production run, but you do need to know if that relies on partC that it connects to being compatible with both versions. It seems like this is the missing information?
I have a 2009 version of JEPC and when there is a supersession there is a pair of curved arrows in a circle to denote that the part has a new number.
Check the housing for an 'O’ring groove.
If the housing is FLAT, use the gasket!!
I think we need owners to post photos of the O-ring and gasket thermostat housings.
That would be helpful . I would like to see a timeline of the changes, photos of all the parts involved. Being new to this myself assuming that EVERYONE knows this makes things hard, like using the terms a-6, a16. I would like to thank everyone who helped me solve this seemingly easy problem.