So I've got both sides' valve covers off my '99 XJ8 and see that when the cams come in line-the flats parallel with the plane of the heads--the left (passenger) side intake cam (the one closest to the middle of the engine) is off. The car's timing is off, no doubt. It made a very nasty rattle and then stalled out on me on the road, but when it was going, it ran very roughly, and I haven't run it since to avoid smacking a valve.

I'm to believe that both sides should match with the flats of the cams, that is the cams on the left and rights sides look the same, and that's what I have with exception of the intake cam. So now the question, how do I adjust that intake cam?




Left side (driver's side in North America) flats are lined up, checked with a straight edge.



Upper cam, the intake cam is obviously out of whack

 

Download my student guide 'ENGINE REPAIR COURSE 168' and follow the timing procedure.
It's in the large file area. I also gave it to GUS and he should have it on his website.

bob

 

Thanks. I'm a bit perplexed in how can the one side intake cam be the one out of whack. Is it possible something broke within the VVT unit to allow that cam to move?

 

My guess would be the tensioner is failing. Those look like the old ones. I hope you update to the new ones. Hopefully the rattle you heard wasn't the valves hitting the pistons. I would do a compression test after new tensioners and the timing is set and before you put everything else on. If they did hit the piston you may need a valve job.

Good luck and keep us posted.

 

Here's a PDF for ENGINE REPAIR COURSE 168.

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

 

You have the old plastic secondary tensioners and the chain 'jumped' a few teeth so the EXHAUST camshaft is now 'out-of-time'.

The engine IS NOT timed at TDC!!!!!!!

Read all you can before trying to repair so you don't have to do it twice.

bob

 

Thanks, Bob. I realize it's out of time. I was in the process of taking it apart to do the secondary tensioners. I have the parts - the new tensioners, gaskets, etc., when I saw the position of the cams. Since the cams on the driver's side are "flat" together in the same plane as the heads (I rotated the crank shaft to bring them around), and the exhaust cam on the passenger's side matches the flat side with what the driver's side has, only the intake cam is out of synch with the rest, so that's why I think it's the one that's amiss. What makes you say it's the exhaust cam that's out of synch?

 

The intake cam is driven by the crank and the exhaust cam usually jumps when the secondary chain and/or tensioner fails. I got confused with your description of the Left Cam and Left Head in the first post. (too many lefts)

Maybe the VVT unit has failed internally and the intake cam is fully advanced????

You might try to grab the intake cam with some locking pliers to see if the cam rotates against the spring pressure of the VVT unit.

The oil pressure should advance the cam when commanded by the ECM but you can move it manually with some force.

As long as the engine crank is locked in timing position, there will be no piston at TDC, #1 is 45 degrees AFTER TDC. The valves will not hit a piston if you rotate cams to wherever you want.

bob

 

As long as the engine crank is locked in timing position, there will be no piston at TDC, #1 is 45 degrees AFTER TDC. The valves will not hit a piston if you rotate cams to wherever you want.


Thanks for this info Bob. Now it makes sense why the crank is locked at 45° ATDC for cylinder #1.