I have a 98 XJ8 with 68K miles and the classic cam chain tensioner failure. This is where I begin to feel real dumb!!! Somewhere in my investigation prior to buying this vehicle I had thought I read that a 99 XJ8 motor would work???

So dumby me buys the 98 in beautiful condition, and I buy a 99 that was wrecked in the rearend but had the engine replaced and transmission rebuilt 30k miles ago. I pulled the 99 engine and tranny first and then pulled the 98, that was when I started to notice subtle differences Cam sensors, coils, intake difference, TBI difference, two sensor on the back of the engine versus 1 on the 98 and few others???

Still thinking that they are interchageable??? I thought then that I could switch intake manifolds, swap wiring harnesses and then swap the necessary connectors to to finish up connection problems.

So girls are sick today and home from school. I decide to check out a few things,I get on the computer and keep seeing more information that the 98 engine and transmission is specific to 98 and will not accept a 99 and newer engine.

So this is what I have:
- beautiful bergundy 98 XJ8 with the motor and transmission pulled and I have separated the intake, and wiring harness. Transmission is separated, I was going to install on 99 motor

-a wrecked 99, XJ8 with the motor and transmission pulled and I have separated the intake, and wiring harness. Transmission still connected

-a stripped down 98 motor, I pulled the head on the side with broken chain, two valves printed on one piston, and those valves are bent. Does not look like piston cracked??? once the head was removed the engine turns over smoothly by hand. There is two small nicks at the top of the cyllinder where the valves hit the piston and then slid into the top cyllinder as they were bent.

I need some help understanding what my options maybe at this point?

Thanks

 

The 98 is probably then an AJ26 engine, where the 99 is certainly an AJ27 and there are some differences as you already noted. You can use the block itself from the 99, and transfer everything from the 98 one. Here is a link with some generic info on swapping engines:
https://www.jaguarforums.com/forum/showthread.php?p=177881
Don’t forget the fly-wheel, this is also changed on the AJ27.

 

Avos,
Thank you for the information. My spirits started to lift, but then as I was reading the other post I started to get this sinking feel that I may have to pull the cams? Since the 99 has the VVT, I was hopping to just swap the harness plugs? both harneses have just two wires going to them. a red and then each has a different color wire?

I switched the sensor at the back of the engine, the AJ27 had two sensors at the rear with different plugs. I figured I could leave the passenger side unplugged?

If I have to change cams I am not prepared for that, none of the proper tools plus would need to have at least one head reworked, unless I just throw two new valves in it. And if thats the case, should I not just rebuild the AJ26? There appears to be many people looking for low mileage, updated AJ27 motors

Since I have the whole car, is it possible/feasable to pull all the electronics and harnesses and replace the 98 internals? There is some much electronic controls in engines these days I am worried about not getting something right and then have a car that won't pass emmisions inspection.

Thanks,
Roger

 

Also, how can I identify the two engine types? I feel sure since the 99 motor was replaced by Jag in 08 that it is a 27, it has a tag on it about being a genuine jag replacement motor.

Thanks,
Again

 

Leave the electronics that is not the road you want to take. In principle 98 XJ8 should also have the AJ27 engine, but as you say there are differences I assume it was an AJ26. How many vanes are on the rear of the cam from the 98 engine?

 

Avos,
Pardon my ignorance but I am not sure what you mean by vanes? I have taken the cams off the passenger side, I pulled that head to see the damage. But since have, put that head and the covers back on too keep for storage. But I did leave the cams out to prevent them from getting damaged. The were held in with 5 braces(?) My ignorance is really showing.

I did right down the numbers off the timing chain cover? The 99 is stamped with XW9 6059 and the 98 is stamped with 9JV 6059. Not sure if this tells us anything?

Roger

 

Am not so familar with non SC engines, so I want to be sure what engine it is you have. A proof for me is the number of vanes, here is a picture that will tell what I mean:

No 1 has just 1 vane, and that is then a AJ26 engine. Obviously No 2 is then the AJ27 (and AJ33/34), which has 4 vanes.

The engine type will determine what you need to swap.

 

I apologize, when I mentiontioned pulling cams, I really meant pulling the heads, even more difficult! That is because the sensors on the front of the heads are different between the two engines.

Also, the 98 has a stamp on the water inlet 980305 0735, no stamp on the 99 motor.

Since the piston did hit the valves, how would I know if the 98 motor is wrecked? the valves imprinted on the pistons and put a slight nick in the very top of the cyllinder. After removing that head, the engine turned over smoothly.

If I have to change heads, why not just rebuild the 98 motor?

Thanks,
Roger

 

So just to be sure, how many vanes on the 98 block?

If you say the senors on the front are already different, then I assume the 98 one is a AJ26 engine, but your answer to the vnumber of vanes wil make it for me 100% sure.

If so, you can easily swap the block with the 99 one, only use the bare block & heads, than reuse all the rest form the 98, so cams, oilpump timing gear, rear drive plate etc.

 

Avos,
The end of the cams look like the end of the cam in your diagram, 2 slots 180 degrees opposed. I can no longer see the part that connects to the end of the cam.

I assume that the cam would have four slots if it was the AJ27? I can pull the valve cover tomorrow, it is starting to get dark and that motor is outside.

 

Its either no1 with 1 vane or no2 with 4 on the intake cam. The exhaust cam doesn't have any vanes, only the 2 slots you mention. If the intake cam looks the same as the exhaust one, then look at the other head, at least 1 intake cam has vanes.
Its already dark here, so am off soon now ;-)

 

I pulled the cover on the drivers side, thank goodness for the little Makita impact driver-with light! It is definetly figure 1.

So we have a AJ26, please tell me we don't have to swap heads?

Thanks ,
Roger

 

So no need to swap heads, take the full bare 99 block (with heads!), but swap the parts mentioned.

 

Avos,
Sorry to be dense, but will I need to change cam shafts? I don't fully follow the info on the link (https://www.jaguarforums.com/forum/showthread.php?p=177881) It reads to me like a AJ26/AJ27--->4.2 litre.

I had planned to swap harness, Intake, Throttle body, A/C lines are different, sensor on drivers side-rear of engine, flywheel, and replace plugs(cut and splice) on front sensor ???

If I have to change cam shafts, I am again at the point of saying why not just fix the AJ26, I would still have to have the speciality tools for setting timing and buy a good many gaskets/seals. Much more worrisome is the idea messing up the timing and trash a perfectly good low mileage AJ27.

I have found a 98 motor with low miles and is supposedly updated for a thousand dollars including shipping, I also found a 99 XJ8 with 58,000 miles that the motor has jumped time, I can buy that for $2500, then the AJ27 will drop write in???

I am so confused?

 

Can't make the choice for you, you'll find lots of articles on how to change timing gear and set the timing right, very easy job, just do it with care and take your time.

If you go for the swap (so to a AJ27) bare engine with heads, then reuse all from your AJ26, so oil pump, timing gear, camshafts/sensors, flywheel/drive plate, and of course all the rest (cable loom, electronics etc etc).

 

Avos, I will try to send a couple of pictures, the cam sensors on the AJ26, appear to be mounted in the front end of the heads. The end of the head has a round stamp in the casting, it is machined out and sensors mounted.

The AJ27 heads do not have that and, the wiring comes out of the valve cover. You can see the raised round stamp on the AJ27 heads, but it is not machined and only one of the two mountining screws is drilled and tapped.

Is there anything that can be done to insure that there is no damage to the AJ26 block, piston, crank, or bearings should I decide to rebuild?

 

I would attach the pics of the 99 and 98 heads depicting the cam sensor positioner? have not figured out how to post pics.

 

Avos, I tried saving the 98 picture as my profile

 

I usually use www.tinypic.com.