Hello,

is it necessary to adjust the valves in a 4.2 l XJ8 from february 2004?
I didn' find this point in the service manual.

With Kind Regards

Tom

 

Nope. No adjustment is typically required. These are solid lifter, shim spacer valve train designs. They seem to maintain the factory spec clearances through valve seat/breakin and well through extended high mileage.

I've checked clearances on several engines when I've exposed the cam assemblies and only found clearances to be off on one engine (two valves out of 24), a V6 Duratech in an X-Type with only 15K miles which I attributed to a foulup during assembly. They're so consistent that I've quit checking now unless there is some sign the clearances are off - clattering or compression loss.

 

Interesting. I know the XK and V12 engines used solid lifters with adjustment shims, but I didn't realise they were still in use. Surely everybody uses hydraulic lifters now to avoid having to shim-up on engine assembly ?

I well remember doing the lifters (tappets) on my XK engines years ago. You would check it all out, and then still find one wrong when you bolted down the cam bearings !!

 

As Stevetech said, there is no need to adjust valves. These engines are designed so that the valve seat wear is roughly equal to the tappet wear, so that the clearances stay in staus quo. If the car has delayed oil changes or other problems, this equilibrium can be upset and require repair, but it would be unusual. This is an area where Jag design has always been good.

 

I'll drink to that one !!