In reply to a message from Kirbert sent Sun 17 Jul 2005:
Thought I’d weigh in on this one-
During the process of putting my '90 back on the road (DPO had
bypassed a leaky heater core…plus more fun and games, too long to
go into here), I went through the cooling system, at least at a
rudimentary level: drained, flushed and refilled, adding Water
Wetter. Purged all the air. Checked this a couple of times.
Pretty confident of no air.
However, I noted the following behaviors: during cooler weather
(e.g., 70 F or less), car stayed absolutely cool. Two needle
widths below N, solid. As ambient temperature moved up, car would
move to N; then, needle would wander- up, above the N (just
touching, with me getting quite nervous), and then, suddenly, drop
to just below N (touching). It would do this randomly. Couldn’t
figure it out. I was speculating that perhaps scale was getting
into the thermostats, etc., etc.
I thought about the fan clutch, and determined to change this. I
used a non-OEM model that one of the Jag parts suppliers use for
this car (well known supplier). Was a bit of a bugger to install,
but, the car runs consistently on or below N, regardless the
weather (it’s been hot, too, here in Cleveland- a couple of dozen
days in the 90’s so far). First clue that original clutch may have
been bad: new clutch resulted in MUCH more fan noise. Noticeably
sucked up HP. Car stays cool, even in stopped traffic at 95F. I
don’t run air (car is a convertible, used only in good weather), so
I can’t say about the total cooling capacity.
I don’t know how to test the clutches, but, I’m not convinced that
a single bench test will necessarily reveal whether the clutch is
good or not. It appeared, on my car, to reveal a propensity for
intermittent behavior.
I have a pair of Spal fans I have to put on, but, I wanted the car
running (cool) this summer, and I figure to do the fans after the
weather changes.
FWIW,–
The original message included these comments:
Years ago Arizona residents had a sure cure for those $&^%#
Hydraulic clutches. They would drill a 1/4 hole through them and
insert a bolt!!!
–
Mike, 1990 5.3 XJS Convertible, ‘Caterwaul’
Lakewood, OH, United States
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