AJ16 Head Gasket

[jeff1954]

HI I'm sorry if this topic has been covered elsewhere but how reliable is the 40 Ltr AJ16 engine as regards head gaskets/timing chains etc. I've seen a 1993 40 Ltr ex Japan car with 43000 mls one owner and I'm interested. Also what is the availability of parts these days for quite an old car.

Jeff

[davidr]

The AJ16 must be just about the most reliable and bomb-proof Jaguar engine ever. I used to have a tatty old X300 with a quarter of a million miles on it. The engine was still sweet as a nut.
43k is nothing - buy with confidence.
Are you sure the 1993 car has an AJ16 or is it an AJ6?

[jeff1954]

Thanks for the reply. I thought the 40 Ltr was the AJ16 and the 30Ltr was theAJ6 If thats not correct how will I be able to tel by looking at the engine.
Jeff.

[cafcpete]

I believe the AJ6 engines when first released were 2.9 and 3.6 then went to 3.2 and 4.0
The AJ16 were 3.2 and 4.0 and only featured from 1995 in the X300 model and later XJS

The XJS always got the biggest version ie 3.6(AJ6) and 4.0(both AJ6 and AJ16)
A 1993 version will be the AJ6.

See https://www.jaguarheritage.com/jaguar-h ... 16-engine/

[ptjs1]

As mentioned, a 93 XJS will have the AJ6 engine. Not as good as an AJ16 but still a strongengine. They can pop head gaskets often between the back 2 cylinders. But at 43k I suspect its had a very easy life.

Paul

[jeff1954]

OK Thank's to you both for that. So what year was the AJ16 fitted, as they stopped producing the car in 1996 Or was the AJ16 never fitted in the XJS

Jeff

[davidr]

Hi Jeff - the AJ16 was fitted for the last 2 years of production (1995 and 1996). It suited the car very well and both Paul and I have one!

[jeff1954]

That's cleared that up then, It's a shame because I really wanted the AJ16 unit as I've read nothing but good reports about them. I've emailed the seller but all I can get from him is that it's an XJ6 engine. Just for the record is the AJ16 unit the one where you can't see the plug leads.

Thanks for the advice.
Jeff

[davidr]

The AJ16 doesn't have plug leads as it has individual coils for each plug so no distributor or leads. It is the one with the smooth cam cover.
I wouldn't write off the AJ6 - its not a bad engine - its just that the AJ16 took it a step further.

[almcl]

As regards the head gasket, I had one go at around a 100k miles. Sometime later I heard a theory that failure to change the in-line fuel filter at regular intervals could lead to a weak mixture and this might precipitate the head gasket failure.

My present AJ6 XJS has got to 105k and has had regular filter changes...

[jeff1954]

Thanks as always for the replies. That's interesting about changing the fuel filter and your mileage almce seems to verify that.

Jeff