1990 Jaguar XJ6 valve readings

DOOMY

MEMBER
1990 JAGUAR XJ6
6 CYL
2WD
AUTOMATIC
94,000 MILES

On measuring the valve clearances due to noisy
lifter sound, I obtained readings of 0.012 to 0.014
on the intake side.
On the exhaust side the readings ranged from 0.012
to 0.026. I can see that these readings(0.026)
are excessive. My question is What caused the
clearance to grow from original settings (0.012-0.014). I would estimate that it could be cam bearings since the engine runs smooth but slightly noisy after a small amount of time. Startup has
more noise in area of larger readings which dissipates a small amount after oil reaches that area.
Can you elaborate on what might have caused the problem.? Shim deteriation? Bearing wear?Cam change. I plan on romoving the lifters in that area to check for damage etc.
Any info would be greatly appreciated
Thanks, Ron rdumaresq@cablenet. Ca

1 Reply

JAMES W.

MECHANIC
2,395 POSTS

Cam bearings usually wear very little over time on a reasonably well maintained motor. The most common measureable wear is dishing of the cam followers and rounding of the cam lobes. As a rule the cam followers will wear more than the cams. When you pull the cam followers, be sure to keep them in order and check foe scoreing on the follower and the head. Hope this helps.