Good evening gentlemen,



I apologies if this is a long read for you. I greatly appreciate if you manage to make it all the way through.




I recently had a couple of friends over to help me do the timing chain job on my 2002 XJR-100.

I followed the infamous 'tmingi chain¨and tensioner replacement' guide. (Someone please tell me why that typo was never corrected?)

There are quite a few missed points for XJR owners (especially late models). I planned to re-write this guide, or at least add some notes to it after I finished. I feel the process can be improved, but currently I am not in position to talk.

We took our time and there were a few tool shop runs as usual. We followed the guides anally and I invested in the correct tools. The locking tools were on both banks and in the CPS hole throughout the process.

When I first removed the covers I found my XJR-100 already had the 3rd gen metal body tensioners. I had issues with British Parts during this which I'll go deeper in to in a separate thread. The new primary guides they gave me did not fit so I ended up using the nylon slippers from the new ones on the old bodies. The slipper were identical (everything checked with Verniers). My tensioners and guides seemed fine. No cracks on the slippers, no heat blisters etc. We decided to undertake the job anyway as I had bought the new bits. Oh how I love hindsight.



Back story out of the way, the car was re-assembled and all torque values checked. All looked good. I started the car and it sounded very rough. I felt sick. It sounded like a heavy misfire. We restarted and checked for codes. Missfire detected on cylinder 1, 2, 3 and 4. The entire right bank.

Fed up, I packed away everything and the car has sat for a month or two.



Finally working up the inspiration to investigate, I removed the RHS cam cover last weekend to see if a cam was out. Both flats were parallel. Confused I pulled the LHS cam cover. The right bank is out compared to the left bank. Oh, there's that sick feeling again.

I have two choices at this point. Re-do the entire job again, this time by myself and not with 2 extra pairs of hands. Just the thought of getting the bonnet off and wresting my impact gun in front the the AC rad again was enough to persuade me into option 2:

Rotate the engine until the CPS and LHS bank are correct, put in the CPS lock and cam lock tool, leaving the RHS free. Rotate the RHS cams until the flats line up again.

My theory was to loosen the primary sprocket and moved the RHS cams back one notch. I made a tool by cutting down a long T60 to get to the primary sprocket. I got the bolt loose. There was not enough slack on the secondary chain as the primary sprocket is one piece. I reinserted the tensioner holding pin and tried to remove the tensioner. Not enough room. Even with the chain completely slack, there’s not slack enough to skip around the teeth. *****.

My next thought is to take of the cam caps from the exhaust cam to remove that completely. I will then need some wrench on the intake cam to move him into position. (It should slip in the primary sprocket as the bolt is loose). I will then reseat the exhaust cam with the flats pointing up, install the cam lock tool in this bank and bolt everything back down.


Does anyone else have any suggestions?


Any advice at this stage will be gratefully received. Thanks for making it this far.



Cheers,
- Richard

 

I am not sure I understand your "issue".
I believe the procedure you need is as follows:
1) Lock the crank with the LHS in position.
2) Loosen both the intake and exhaust sprocket bolts on the RHS
3) Using the cam lock tool and a pair of channel lock pliers with a rag in the jaw, turn the cams as you tighten the cam lock so no no extra force is applied to the cam flats.
4) Tighten the sprockets down.

It has been a while since I actually did one, but I am fairly sure that is the correct procedure. I am sure others will comment with other plans of action or to correct what I may be missing!

Now, for interest sake, I have a question for you. Was the primary chain in your XJR a roller style chain (like the secondary chains) or a Morse style silent chain? On my MY02 XJ8, the factory tensioners were Gen III like yours, and the primary chain was a Morse style.

 

Hello,

Thanks for the reply. My issue is simple, my engine is out of time.

Should the cams be hard to turn with the valve spring pressure on the lobes? I don't want to force anything as the cams are about £500 each.


Yes, my late model engine has the Morse chains, but British Parts sent the standard chains even thought they knew my chassis number and I bought the kit for the late model cars. I therefore re-used the old chains as the condition and length were still good.



- Richard

 

I meant the issue with what to do. The valves will have some resistance to turning, but it is much safer to turn them with pliers than to remove bearing caps, especially since you cannot control the angular location as you remove the caps and there would likely be lobes engaging valve followers, giving side load to the cam.

 

Oh I see. Apologies. Yes, I was just confirming that my theory was correct. I was half expecting the usual forum replies of "take it to Jaguar", "Buy a new car", "you've ruined it" etc etc.



I have now rotated the cams. There was not really enough room for channel lock pliers without denting the internal edge of the head. I managed to use a small bar with a rag in the slot for the cam position sensor lobe. I did this slowly bit by bit and now the cam lock tool is on. I don't know how much tolerance is on these timing tools, I guess one side of the flat can be 1mm or so higher than the other?

I need to purchase some crows feet open spanners so I can get my torque wrench onto the cut down T60 bit.


I will then turn the engine over a few times manually and see what's what. Any other safety checks before re-assemblying and firing up? Or should I already start looking for spare engines?



Cheers,
- Richard

 

First, I would not sweat it at this point. If it just a little off on smooth idle it is likely just the timing and you have not bent anything! As soon as you get it timed, you should probably do a leak down test.

As to getting to the cam bolts for tightening... As I recall, I put a piece of scrap brass on the edge of the head valve cover lip to keep from buggering the edge while I tightened the bolts.

It sounds like you may not be using the cam lock tool. It is essentially a flat bar that lays on top of the two flats and is tightened down against them, using holes in the head. Someone has posted dimensioned drawings on here, but I am not sure exactly where. I would suggest trying to do a little better than a straight edge across the flats" while tightening the bolts in order to keep everything in line while snugging the bolts. That said, you can probably do OK with a flat bar with some holes in it if you are careful to get it all parallel.

You seem to understand that the cams are fragile- they are supposedly hollow cast for weight reduction, and you do not want to apply much radial force to the lobes nor bending moment along the length?

 

Fingers crossed you haven't upset the cam sensor setting by using a bar on it, if it's out it'll still run like a bag of crap even if the timing is 100%. The reluctor is just pressed in so they can be adjusted...

The cams are tubes but are designed for radial force (axial twist - or they'd be no use), this is why Jaguar put the hump in the middle so they can be turned into position, it's bending moments they don't like. I've found the secondary chains on this version of engine have a very very small chain stretch that doesn't effect timing.

A little research would on your car's engine (AJ27S) would have avoided the work

 

I only used a bar on the exhaust side as there's a notch as there's no reluctor installed. I used the flat in the middle for most of the turning until I hit a dead stop against the block itself. There is only one flat with not much room to work with either side.


I'm not sure however how a little research would have avoided the work. The only difference being I'd have a new primary chain on now. I'd have hoped that when you give a 'specialist' parts supplier one's VIN, model and year for a late engine chain kit, they'd supply the correct chains. Even with the new chains I guess I'd have still jumped a tooth for whatever reason it did. But thanks for the advice anyway.



Sparkenzap: Yes I do have the proper timing tools (I have been using the bolt down cam lock bars on both sides). It was this I was referring to when asking how much tolerance there is from the lower face of the bar to the top of the flats. If there is some gap, then the flats can still be at a slight angle, as just one edge of the flat will be touching the bar. I hope this makes sense.





- Richard

 

Yep, Richard. I understand now.
Anyway, with luck you have not crashed the valves and all will be well once you get 'er back in time. After rereading everything, it seems like your cam timing might have been far from right. Hope not!
You have proof of the old adage, I suppose; "Too many cooks spoil the soup."