After 99000 miles, one of the secondary timing chain tensioners in my 2001 XK8 disintegrated last month. No prior warning rattles, but a very loud noise as the tensioner broke, the secondary chain broke, a few teeth stripped off the secondary cam sprocket on the intake camshaft, and two exhaust valves bent. I had it towed home!

Prior to this failure, I had been hoping that the lack of warning rattles indicated that I did not have a tensioner problem, but have now learned the hard way that I should have dealt with this earlier!
Hopefully some readers will take this to heart and change their tensioners before it's too late!

Anyway, I worked through the process of replacing all of the tensioners, and obviously also had to remove the cylinder head to replace the bent valves (and valve seals).

Put it all back together and it started first time, which was encouraging. It drives fine and I expected to run a little rough as the ECM settles down, but it's throwing P0305, P0306, P0307 and P1316 codes. Number 8 cylinder seems good so far.

I tried swapping around plugs and coils, but whatever the combination, I don't get a P0308 and I always get P0306 and P0307.

I've only driven it on a couple of test runs of a few miles, as I don't want to damage the catalytic converters if the misfires are serious.

The valves I replaced were cylinders 6 and 7, so I'm suspicious.

I did a compression check and all 4 cylinders on this bank were about 110 PSI. so looks like the new valves are seated OK. When rebuilding the head, I used a simple fluid check to confirm that the valve grinding was OK.

So the question I have is this:
Should I continue to drive the car for 50 miles or so, and hope that this is an ECM learning issue?
Or
Should I assume that I have some other problem and start looking at the injectors etc.
Or
Might I have a timing issue which is causing the misfires? (I used the crankshaft TDC and camshaft locks to refit the chains, so don't see how it could be wrong)

Help!

 

It could be injectors, but I would also check the valve clearance, and confirm that the cam flats line up. One thing I'm sure of is that it's not ECU learning.

 

+1
You're not getting P1313/14 so it's only reporting excess emissions rather than catalyst damage but I'd be wary of continuing to drive the car:

 

Did you use the correct tool to hold the torque converter drive plate? TDC is not the correct crankshaft position for setting the valve timing.

Refer to the first section on page 70 concerning the position of the crankshaft:

http://www.jagrepair.com/images/Auto...Code%20168.pdf

 

RJ237. Thanks for this. The valve clearances were all good, although one of the new valves in cylinder 6 was a little on tight side. 5 and 7 were both right on, so unlikely that it's a valve clearance issue, at least of those two cylinders.
Noted re ECU - that's very helpful to know. I'll check out the fuel pressure then take a look at the injectors. May have got some dirt in the fuel rails while they were off.

 

NBCat
Thanks for this and for the link, which is very helpful.
Yes, I had all the right tools to clamp the camshafts and lock the crankshaft, so timing should be good.
My bad re TDC...I see from your attachment that it's actually 45degATDC.

While on the subject of tools, one of the most surprising problems was the lack of a proper tool to hold the crankshaft while tightening the pulley bolt. I bought the clamp to hold the crankshaft pulley for removal, but it doesn't work for re-installation. That Jaguar actually recommends jamming a piece of steel into the torque converter plate was surreal. It took several hours for me to devise a system of multiple bottle jacks to jam the steel bar in place. Surely there must be a real tool to do this job?

 

Cut the old serpentine belt and wrap it around the crankshaft damper pulley, then use a chain spanner (wrench) to hold the pulley whilst tightening the centre bolt.



This image is courtesy of motorcarman

 

NBCat.....that's an OK solution once the split collar has grabbed the crankshaft, but until it does you need to lock the crankshaft some other way. I have the special tool to hold the crankshaft pulley anyway, but it doesn't hold the crankshaft, only the pulley.

 

I was not aware of this.
​​​​​​I recently had my crank pulley off for a supercharger drive upgrade and had no problem restraining the damper for both removal and refitting of crank bolt using normal tool bought online.

 

Read the procedure in the training course. The link is in post 4.

Also, under no circumstances is the engine to be rotated in an anti-clock direction when viewed from the front of the vehicle. Excessive wear to the main and rod bearings is the result.

 

Per my earlier post about misfire after replacing tensioners, I'm happy to say that I have now resolved this problem. I had made an elementary mistake.....Here's what I did:

The misfiring was bad enough to make me suspect that my timing was at fault, so I removed the valve cover from the bank which was misfiring. I immediately saw that the camshaft flats on the inlet and exhaust cams were not aligned together. I knew that when I did the timing, I had used the cam locking tools to set up the timing, so something had obviously gone wrong since then. I put in the crankshaft locking peg, and it showed me that it was the inlet cam that was "off" by about 15 degrees or so.

After much pondering and research on this forum I discovered my elementary mistake. I had been following the truly excellent Black Onyx procedure when doing the tensioner replacement. However I found that this procedure does not include a step to reset the CVVT retardation before tightening the camshaft sprocket hex bolt. (my XK8 is 2001 and I think the Black Onyx procedure was for a year or two prior, where there is no such VVT adjustment necessary). I awoke in the middle of the night with the sudden realization of what the unused tool in my timing tool kit was for!!

This meant I had to start all over again and remove the timing covers etc. I'm happy to report that it is MUCH easier second time around! I now have it all back together and back on the road. No misfires, and it runs smoothly, although I do still have a sporadic P0172/P0175 fault which I had before tensioner problem, and which I'm still working on.

So here's a few things I learned while doing this job:

1. If you haven't replaced your tensioners, do it NOW!! It's not so hard if you get the right tools and follow the right process. I thought my tensioners were good, but they failed. Here's a picture of all of the broken bits:





a) Teeth broken on secondary sprocket<br/>b) two bent exhaust valves and seals<br/>c) secondary chain, mangled and broken<br/>d) cracked primary tensioners<br/>e) Cracked secondary tensioner, about to explode<br/>f) fully exploded secondary tensioner!!!


2.. The Black Onyx procedure is extremely good. You can find it at:

Tmingi chain and tensioner replacement

3. If you have the CVVT camshaft, you need to supplement the Black Onyx procedure with the CVVT Retardation process. This is shown at Step 6 in Jaguar 303-32 Technical Bulletin. You can find this at:

JagRepair.com - Jaguar Repair Information Resource

4. I bought the Jaguar timing kit on ebay for about $50. There are plenty of vendor options
I bought this one





5. I bought the crankshaft locking tool on ebay for about $125. Once again there are multiple vendors.
I bought this one:






When I first used this tool, the removal of the crankshaft pulley worked just fine, but I could not get the tool to work for reinstallation. I ended up devising a system of jacks and a steel bar to wedge into the torque converter plate. However you do NOT need to do this.

The problem I encountered first time round was that the new crankshaft pulley bolt was so tight going in to the crankshaft that the crankshaft started to turn before the bolt started to touch the split collar. So I had to wedge the crankshaft just to get the bolt in far enough to meet the surface of the split collar.
Second time around I used a different approach. Firstly I cleaned out all traces of old Loctite from inside the crankshaft thread. I used the old crankshaft bolt as a tap (as in tap and die), cleaned out the crankshaft thread a quarter turn at a time. I tapped the bolt so that it screwed in easily by hand right up to the split collar.
I then took the new bolt, which came precoated with Loctite. and removed the loctite (steel brush works fine) . Once everything was clean and ready, i used new Loctite 270 on the new bolt and tightened it immediately while using the crankshaft lock tool. The Jaguar process says you have 7 minutes to complete this task (presumably because of the Loctite curing time). I was worried that I couldn't do it that quickly but it worked perfectly.

To get the correct torque for the crankshaft pulley bolt was a guessing game first time round, but I found a procedure in Technical Bulletin 303-05

You can find this at

JagRepair.com - Jaguar Repair Information Resource

The important point is that you tighten with a regular torque wrench up to 80Nm (59 ft Lb), then an additional 80 degrees. This results in approx 320 -400 Nm torque. Simple!


5. I bought most of my parts and tools on eBay. I did buy a new crankshaft bolt from Jaguar because I was in a hurry. It cost me $43, but I got it quickly. (Under $10 on eBay!)


Here's a list of what I bought:

Head Gasket $36 (new, eBay)
Thermostat housing $53 (new eBay)
Part load breather hose $38 (new eBay, broke mine removing it)
Timing tools $46 (new, eBay)
Pulley removal kit $125 (new, eBay)
Timing chain/tensioners kit $112 (new eBay)
Camshaft & CVVT sprocket $65 (used, eBay)
Timing cover gasket $29 (new eBay)
2 Exhaust valves and seals $50 (new eBay)
Valve cover gasket kit $60 (new eBay)
Crankshaft pulley bolt $43 (jaguar....<$10 on eBay)
Valve spring compressor $20 (used, eBay)

plus probably $150 on miscellaneous items like valve feeler gauges and consumables like valve grinding paste, gasket sealant, Loctite 270, some generic tools/sockets/ etc

I did not replace the inlet manifold gaskets as they were fairly new.

There's probably a good argument for using more genuine OEM parts than I did, but I'm back on the road for about $750 and can probably on-sell some tools. And you don't need to remove the cylinder head and replace valves if you do the tensioners before they fail!@ That will reduce the cost a bit.


All in all a great learning experience. It took me several weeks as I had to order and wait for many items, but a rewarding result.
Thanks to all who responded to my original post, and to all of those who have previously posted on Jaguar Forums...This project would not have been possible without this resource. And this is why I have taken the time to summarize my experience...I hope it helps someone else in a similar position!

 

Brilliant to see such a full post that's updated by the original poster with the fix.

You sir are a gentleman, and it also shows how a forum should be used well