I was going about changing the secondary chain tensioners on my 99 XJ8 and when I got the "A Bank" I noticed the "flats" on the cams (to which the locking tool engages on") were not "flat" with each other.

The intake cam was advanced about 15 degrees relative to the exhaust cam.

To "fix" the problem I took a pair of channel lock pliers, grabed ahold of an unimportant part of the intake cam (i.e. not the lobes) and turned it to be flat to the exhaust cam. Basically the cam rotated "inside" of the VVT assembly.

Before I started this the computer was complaining about the VVT malfunctioning on bank A - now I know why.

It appears that it is sticking but maybe there is something else going on? Is there some solvent I should spray into the VVT oil galley that could de-goo the unit?

Thoughts?



Thanks...

 

When the A bank exhaust camshaft is at its proper timing position, one pair of cam lobes is holding valve spring pressure. Sitting here at my computer, I'm thinking it's A3. Since the engine is not running, the primary timing chain for the A bank is not under tension. The exhaust cam will rarely stay put at its timing position, as the pair of tappets pushes the cam lobe and rotates the cam out of correct orientation. That's why you need the lockdown bar to hold the cams correctly, and why the exhaust cam moves when the tool is unbolted. The exhaust cam will be correctly oriented when the engine is running, since oil pressure is now operating the primary tensioner and eliminating the slack in the primary chain. This also explains the need for the chain wedge tool when resetting the intake camshaft timing in cases where the VVT unit has been loosened or removed, as when replacing either primary or secondary timing chain.