How long should I expect my 4.0 L6 in 1994 xjs last? I now have 120k miles and I drive it everyday. I plan on rebuilding the heads soon. My main concern is the lower end. Will this go to 300k like some other cars? Toyota, BMW, VW, etc.

I have been looking at the engine swaps from jagspecialties to prepare myself for the day it goes. I guess I do not want to put money into rebuilding the top end, etc through the years as I need to replace the bottom end at 150k.

So who has a high mileage jag? How many miles?

 

also, will an xj6 4.0 head fit on an xjs 4.0LS?

 

The inline 6 engine is pretty indestructible and serviced properly and regularly you would be very unlucky not to get 250,000 miles out of it with no major work of any sort required.
There were two iterations of the 4 litre engine, the AJ6 and the AJ16 (I think). The head of an AJ16 will swap with an AJ16 and the AJ6 with an AJ6. So you would need to identify which 4 litre version each car has.
Whether an AJ6 will swap with an AJ16 I do not know, but I suspect the bare head itself is the same.


Greg

 

hoodun,

I'm not quite sure what you mean by "L6" or "4.0LS". I'm guessing those are Americanisms for the various 4.0 six-cylinder engines?

Do you have an AJ6 or an AJ16 in your 1994 car? Both engines are very reliable, the AJ16 somewhat more so. AJ6 engines can be slightly more prone to blowing head gaskets, usually on the back 2 cylinders, but they can still rack up big mileages. The AJ16 engines are less prone to head gasket problems but more prone to exhaust manifold cracks. I know of owners with 250,000+ miles on untouched AJ16 engines.

The AJ16 head can be made to fit the AJ6 block but there are differences in exhaust manifolds etc. I have read of a few owners who have done the swap.

The whole AJ16 setup can be fitted in an AJ6 car but requires quite a bit of work as the ecu, ignition systems etc are all very different.

The bottom end of both engines are very, very strong. We very, very rarely hear of any owner having to work on the bottom end of an engine. I don't know any owner who's done a bottom end rebuild.

Frequent oil and coolant changes and you're in for 200k+, I'd say. I consider my 1994 AJ16 to be in its infancy at 85,000!

Good luck

Paul

 

Not sure if it's still true but 4-5 years ago it was impossible to buy crankshaft and connecting rod bearings for the 4.0 six cylinder. They were NLA from Jaguar and no aftermarket suppliers picked up production. There was simply no demand.

I also remember one of the 'usual Jag suppliers' trying to sell a slew used 4.0 engines they has collected from wrecked cars. They were down to something like $300 each and still sat unsold and unwanted.

That should tell you something about the Jaguar 4.0 L6

As a minor point, though, I'll mention that what we're really talking about in this thread is durability, not reliability....although the two certainly can overlap

Cheers
DD

 

I was wondering about the "LS" thing myself.

"L6", though, would be any inline 6 or straight 6. L8 would a straight 8. Etc.

Not sure how the "L" identifier came to be used, but it's been around for decades in the USA


Cheers
DD

 

I have almost 200,00 miles on my 1995 coupe. I believe the AJ16 has a 250K mile service life. I would not be so worried about the engine as I would about finding another EMU when iit gives out.. There are other electronic parts that are no longer available also... That is this car's Achilles Heal.

 

I asked the same question not long ago. My 1994 4.0 has 204k and its no different than when it had 130k. I just keep driving it so that it doesnt breakdown in the driveway doing nothing. Im trying to get at least 350k out of it

 

I checked the valve clearances on my AJ16 at 154,00 miles and they are all in tolerance!! Amazing engineering and quality - still pulls like a train and does not use much oil.

 

Agree with mileage probability. 225K on mine. No noise, smoke and drop in performance. Straight 6cyl engines are inherently bulletproof. Change the oil, watch your fluids and use only premium gas.

Dave in AZ

 

The rest of the car will collapse into dust before that engine goes. 200k on mine and it survived two major overheating incidents… a failed thermostat and a separate failed octopus hose that emptied radiator. I only parked the car because clearcoat and interior were shot.