[x300] Calorstat Thermostat - 98 XJ8 4.0 mod required to make it fit

Since completing the transmission rebuild, I’ve busy
catching up on outstanding mtce routines on the Jag…

I recently changed out the Thermostat as part of coolant
replacement, The OE p/n is AJ86484 with the OEM supplier
being Waxstat. This year I had been having the fans run on
occasionally post shutdown regardless of how warm it was
(and it never gets really warm on Vancouver Island) so I was
pretty sure the thermostat was on its way out.

The following is an FYI on the thermostat I ordered, a
Calorstat p/n TH5753.84J - which is shown in the Calorstat
catalogue as a cross reference to the OE p/n. Dimensions
and temp (84 C) all matched OE so I ordered it.

When installing the unit I found that while the dimensions
are correct, the Calorstat has a raised circular central
section while the OE unit is flat. While this shouldn’t have
been an issue, the plastic (OE) thermostat housing I have
has a narrow (@ 2mm wide) flange inside the housing that
butts against the face of the thermostat, presumably to help
keep it in position. This flange hit the raised centre
section preventing the Calorstat from being seated. On the
Waxstat, the flange just butted the surface of the
thermostat.

Rather than return the Calorstat, which had come as part of
a shipment of a winterizing material for the household cars,
a process that would take several days, I was able to make
it fit by shaving about 1mm off the top of the flange. This
was all that was required to clear the raised central
section and still left lots of material to support the
thermostat in position.

However, this is a less than elegant solution and I think
most would prefer stick with a unit that fits right out of
the box (NB I don’t know if the flange found in my housing
is the same on all engines or was changed in later
versions).

FWIW
Scott

ps - I’ve had no fan run-on since changing the T’stat, so am
sure I found the cause of the run-on–
SAR 98VDP
Vancouver Island, Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

In reply to a message from sarvdp sent Wed 10 Oct 2012:

Scott…I hope you remembered to include a new rubber flange seal
when you fitted the stat.
It slips around the outer edge of the stat. and the plastic thermo
housing buts against the rubber seal, not the stat body.
And this must not be overtightened…more peopel have problems
with these by over tightening.

Cheers,
Maximus–
The original message included these comments:

Rather than return the Calorstat, which had come as part of
a shipment of a winterizing material for the household cars,
a process that would take several days, I was able to make
it fit by shaving about 1mm off the top of the flange. This
was all that was required to clear the raised central
section and still left lots of material to support the
thermostat in position.
However, this is a less than elegant solution and I think
most would prefer stick with a unit that fits right out of
the box (NB I don’t know if the flange found in my housing
is the same on all engines or was changed in later


Max Heazlewood '98XJ8http://www.pbase.com/padme002/jj_jag_1
Tasmania, Australia
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In reply to a message from Exjay8 sent Thu 11 Oct 2012:

I didn’t put it in my post, but another complication to the
Calorstat is that you need both the flange seal and an O-
ring for it to seat correctly because of the way the flange
surface is constructed. Both are included with the
thermostat so not a big deal.

Over-torque is a huge no-no and when I have a part with an
O-ring sealing surface I rarely tighten do more than snug it
up plus a half turn on each fastener and then watch for
leaks & only snug up further if a leak appears. There’s
nothing worse for an O-ring than being over compressed (& as
you say, over-tightening is death on old, brittle, plastic
parts).

The only reason I posted was that I never saw a waxstat on
my searches of the online houses I use when placing orders
for multiple cars (my winterizing order also included a Saab
and a Suburban). Outside of no-name parts tht coudln’t be
verified, Calorstat was a constant on most sites and on many
the Beck Arnley was also a Calorstat. Unfortunately, the
local parts shops (Napa and a BC franchise called Lordco)
aren’t the best for many Saab or Jag parts, so online is the
only route & I need to batch orders to avoid huge shipping
costs…–
The original message included these comments:

Scott…I hope you remembered to include a new rubber flange seal


SAR 98VDP
Vancouver Island, Canada
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