Hi there to all ! I just register to the forums but to be honest i checked them through the years a few times before.I have a 1998 xj8l 4.0 with the aj26 engine for the last 13/14 years.I had barely covered 100.000 km with it and during the last year i had done all the necessary upgrades like the uprated chains with metal tensioners,aluminium thermostat housing and new thermostat,new water hoses and pipes(including the complex one under the intakes),new water and petrol pump,new serpentine belt etc..A few days ago during the morning when tried to start the car i heard a horrible noise of something breaking for a second or two and then the engine continue to idle while making a low grinding noise...I turned it off and towed the car to a motor shop where i heard the bad news that it was a broken rod/piston....
Since then probably i feel way too horrible for any sane person to feel for a car...yet i really love the car and want to fix it but this time i don't know where to start and i hope i could get some advice from more educated people here. Is it worth rebuilding or better try to find a new engine ? Can it be any engine ,meaning if it is an aj27 will it work and will it need anything replaced to work properly(harness ,ecu etc..) ? Does it matter if it is a different variation of aj26 ? (because whenever i bought parts some parts where different depending vin number even cars that should have aj26 engine have different variations as my is a very early car before VIN (846534) yet there are parts different after that vin but before VIN (853935) so both are aj26 ....
In case i rebuild the engine how i find what pistons,rings, rods and bearings i need ? I checked in sites like sngbarrat and it seems a lot of parts of early engines are out of stock.Can other pistons (with their equivalent rings) ,rods and bearings be used? Or they are different ? And about sleeves ? Where can i find them? Or is it something that the machine shop will make ? Does it matter that my engine is one of the early nikasil ? Sorry if i ask stupid questions but its all new to me...

 

Depending on the overall condition of the vehicle, it would be most cost effective to find a used engine from a breaker.

Did the Jaguar specialist offer a reason for the connecting rod to break? Did they disassemble the engine to make the diagnosis?

 

Hi there thanks for writing back! The engine will be disassembled next week.As far as replacing with a used engine what engines can i use? As my is an early aj26 can i use an aj26 engine from a later vin car ? As far as aj27 can i use it and if yes what else should be replaced? ( engine harness,ecu etc..) Sorry for asking basic things but i am at a loss currently what to do!

 

You can use another engine, but some of the parts such as the sump are different and must be swapped over. Also, if you decide on installing a used engine, have the timing chains and tensioners checked to ensure they're the latest style before going any further.

The Nikasil engines, if not exposed to poor fuel, can last longer than the later engines with steel liners.

 

1. Any AJ26 engine (except supercharged version) will just "plug-in".
2. If going for AJ27, the following should be done (others may add if I have missed anything):
a) Do not plan to go for AJ27 ECU, harness etc. as it will be extremely difficult (if not impossible) to "marry" all the electronics
b) You will have to remove the AJ27 reluctor at the back of the left head intake camshaft and attach the reluctor from AJ26. AJ27 has two camshaft position sensors (one on each cylinder head). Leave the right head sensor in (as a plug for the hole) but it will not be connected.
c) Transfer the flex plate from AJ26 to AJ27.
d) Transfer the Knock Sensors from AJ26 to AJ27.
e) Transfer the Throttle Body and the intake elbow from AJ26 to AJ27.
f) Transfer the Air Flow Sensor from AJ26 to AJ27
g) You may have to also transfer the fuel injectors but the AJ27 ones may work fine.
h) Transfer the AJ26 ignition coils from AJ26 to AJ27

There could be some other things to transfer, others may add. Basically, keep everything on your AJ26 engine until you complete the swap and start the AJ27 engine. Search the forum, there was a thread on AJ26-AJ27 swap.

 

The valve covers (or cam covers) need to be removed from AJ26 engine and added to AJ27 engine.

The engine wiring harness will have to be removed from 26 and installed to the 27 engine.

The timing cover has to be swapped over since you have the early VVT’s.

I would recommend just swapping over both intake camshafts due to the early vs late VVT timing gear is quite different. That “B bank” reluctor on the back of the intake camshaft that M.S. is talking about is pressed on there pretty tight. I saw my boss remove one before and I thought he was going to hurt himself in the process. However... you must have the valve clearances checked swapping over the camshafts. The lifter buckets 26 vs 27 are a little bit different!

I believe there’s 2 oil switches (temperature & pressure) that need to be swapped from 26 to 27. It has to do with the electrical connectors being different.

One last thing. If your engine has an external oil cooler mounted in front of the radiator, you will need to get a replacement engine with the same configuration. Just bring that up to the shops attention and let them deal with it but tell them not to scrap the old engine before your car leaves the shop running without any issues. You can get an engine that doesn’t have a provision for an external engine oil cooler installed in your car but that’s between you and the shop.

 

Awesome knowledge/info for OP!

 

Thanks for the information ! Through as far as replacing with a used engine a similar aj26 sounds like the best bet if i find a aj27 is it more reliable than the older aj27 or it does not matter ?

Also if i got everything right i should leave the existing harness and ecu intact and replace what you told me BUT do i keep the aj27 (if i find a aj27 engine) camshafts and cam covers and just unplug the right sensor and replace the left with the one from the aj26 and lastly replace the reluctor
OR do i replace the camshafts with my current aj26 ones along the cam covers ? And can the aj26 cam covers fit properly over the aj27 engine ?
..Also what is the reluctor ?

Also if i go for a rebuild where do i start ?

 

If I were you, I would have them pull the cam covers off to see if a chain snapped (or something up top) and I would have the lower oil pan pulled to see what kind of shrapnel you got. If there’s a large amount of debris in the pan, then I’d say that motor is not rebuildable. I would check the engine oil level and coolant level first to see if it’s adequate. If so, why did the engine get damaged?? It is possible that whoever did the timing chains, guides and tensioners didn’t do a good job or a new component failed. Something to think about. Get the receipt out for the chain, tensioners and guide repair and notate date of engine failure and see what that warranty may cover (if any).
Even if you’re engine is rebuildable, the cost of doing so is staggering. I would source the lowest mileage preferably a 03’ engine since everything is updated. Have a new water pump, rear main seal (including cap seal just above rear main) and transfer everything over that’s been discussed in this thread.

 

I always wondered how much would custom piston cost from arias ..

 

Again thanks for the information but please clear a few things ! If i go for an engine swap and find a aj27 SHOULD i change the camshafts along the cam covers of my broken aj26 engine along the left cam sensor OR just replace the left sensor,unplug the right one and replace the reluctor on the left head intake ? And about lifter buckets at this point i am completely lost... can the camshafts be swapped or additional things should be replaced so they can be swapped ?

And about the reluctor ... How can it be replaced ? Is it pressed on the rest of the camshaft or can it be removed and HOW ?

Is trying to find a straight swapable aj26 engine a bad idea ?

And about rebuilding....As my engine i an early nikasil engine.... What about sleeves ? Are there available sleeves for the aj26 engine ? What pistons should than be used etc.. ?

 

The simplest way is to just replace the reluctor on the LH intake cam. I think that was what a member here did when swapping AJ26 to AJ27. It is not difficult at all, I have removed a couple of reluctors - use a piece of hardwood on the "fingers" of the AJ27 reluctor to knock it out (alternating between opposite sides) than simply hammer (plastic) the AJ26 reluctor in:

You can keep the AJ27 LH cam sensor if its connector is the same as on AJ26 sensor, otherwise swap them.

You don't need to worry about AJ26-AJ27 different cam followers. They are matched to the head, i.e. the valve lengths. As you will be using complete AJ27 heads with their cam followers, there will be no issue about the follower differences. Even if you put the AJ26 camshafts (not necessary) on AJ27 heads and their cam followers, this will not cause any problem related to different cam followers.

If the Nikasil lining on the affected cylinder is damaged, it is not easy (and would be quite expensive) to repair. There are no liners for these engine blocks so you would have to have steel liners custom made (all 8) and pressed-in and buy 8 new pistons. Some specialists may be able to re-apply the Nikasil coating but, as in the case of custom liners, too expensive - better buy another engine. Otherwise, the blocks with Nikasil liners use three very slightly different piston diameters, matched to the exact diameter of each cylinder after application of Nikasil. The pistons are called "Grade 1", "Grade 2" and "Grade 3". What pistons your engine has is stamped on the left side of the block as a set of 8 numbers like, for example, 22122312 (grades) referring to cylinders B1 B2 B3 B4 A4 A3 A2 A1 respectively. If replacing a piston (in the case the Nikasil is not damaged), you must get a piston of appropriate grade.

 

Please let us know what you decide to do and how it works out. Good luck with this project