[xj-s] Fan pulley/idler pulley alignment

Today I was going to reinstall the fan and shroud after the front
crankshaft seal replacement.
Along the way, I noiced that the fan pulley and idler pulley are not
properly aligned. The fan
pulley is about 0.060" forward of the idler pulley. Since I had just
replaced the fan pulley,
I figured it might be the wrong part, so I put the old one back on to
check. It too is misaligned,
meaning that it must have been running this way for some time.

Closer examination shows that the problem is probably with the fan shaft
A brief description of what I see may help you see my problem.

It looks like there is a bearing/shaft assembly that fits into the
aluminum idler/pulley housing.
Onto the end of that shaft is pressed a flange/shaft unit to which the
torquatrol clutch
attaches at the end of the shaft, and with the fan pulley mounted on
the integral flange.

The problem seems to be that the flange/shaft unit is not pressed
tightly against its shoulder.
I was about to rush off to a machine shop to have it pressed properly
against the shoulder
when I noticed that the the gap between the shoulder and the
flange/shaft unit is larger than
the pulley misalignment, measuring 0.095". So, if I press it home there
will be a 0.035"
misalignment the other way!

So the question is, is this just poor quality control at Jaguar that I
have to live with, or is there supposed to be
some other way to get these two pulleys aligned? For example, I notice a
Allen set screw
with lock nut on the idler pulley housing centered under the
bearing/shaft assembly. It must have something to do with locking
the bearing/shaft assembly to the housing. Does this offer an alignment
adjustment opportunity?

As you might be able to see from the above description, on my car the
mounts with a single, center bolt; I believe later models are mounted
with 4 bolts. However,
I think the rest of the assembly is the same.

Ed Sowell
76 XJ-S

Being unable to push the fan pulley back, I decided to shim the idler pulley
with a 0.035" brass washer behind the idler arm fulcrum. This cut the
by half. I would have added one more, but this tends to make the adjuster
bolt and trunion misaligned with the arm, so I compromised.

I then put the unit back on the engine
and with a straight edge on the crankshaft pulley was able to see that the
pulley is still about 0.030" (an eye-ball guess) back from that pulley. I
assume that
it is the idler pulley or arm that is wrong. I have records of it being
replaced in '84,
and there is still grease pencil markings “GOOD” on it, so I assume it came
from another
car. So either there as a small change in the part between '76 and whatever
year it came off of, or I am seeing unavoidable pulley misalignment due to
manufacturing/design tolerance “stack up”. Since the car has been running
misaligned by the 0.060" for 16 years, I guess it’s OK.

Seems like I’m the only one interested in this fascinating issue!

Ed Sowell
76 XJ-S