[xj] Overheating when stationary

XJ
21

Spent some time today doing the Gardner, a/c compressor cutoff and
aux-fan-on-with-compressor mods. (Jag-lovers is great!) While in the
process of wiring in the diode for the aux fan mod, I noticed what looks
sort of like an in-line fuse holder for modern flat fuses, only bigger.
It has a green/brown wire and the green compressor wire as inputs, and has
plastic clips to retain the item which is plugged into it.

The part is still plugged into mine, but the plastic cover over it is 60%
missing, leaving the fuse(?) exposed to the elements. The holder itself
is fine, it’s just the item being held which is broken.

Is this in fact the (50A?) a/c compressor fuse? And (either way), can I
replace it with an OTC part, or must this item be prescribed by the Lords
of Lucas?

(The a/c works great, but…)–

  • bill
    '84 XJ6 (Julia)

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22

sort of like an in-line fuse holder for modern flat fuses, only bigger.
It has a green/brown wire and the green compressor wire as inputs, and has
plastic clips to retain the item which is plugged into it.

snip

Is this in fact the (50A?) a/c compressor fuse? And (either way), can I
replace it with an OTC part, or must this item be prescribed by the Lords
of Lucas?

Bill, if this item is indeed hanging near the compressor itself, it sounds
like the thermal fuse that’s used in conjuction with the superheat switch
compressors.===================================================
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23

Bill,

This is the thermal limit fuse switch used on the early XJ6 A/C

systems with a Superheat switch.

I purchased two of these recently at MOTORCARS LTD for about $4.

Their part number is IN100137, the Jaguar part number is DAC-3374. I
have no affiliation with MOTORCARS LTD other than being a satisfied
customer.

You didn't mention the third wire. It's a black wire with a

white connector that attaches to the Superheat switch on the back of the
A/C compressor.

Regards,

Paul M. Novak
1969 E-Type FHC, 1984 XJ6 Vanden Plas
San Diego, CA
@Paul_M_Novak-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf
Of William Watson
Sent: Thursday, October 16, 2003 6:40 PM
To: Jag Lovers
Subject: [xj] A/C Compressor - Inline Fuse?

Spent some time today doing the Gardner, a/c compressor cutoff and
aux-fan-on-with-compressor mods. (Jag-lovers is great!) While in the
process of wiring in the diode for the aux fan mod, I noticed what looks
sort of like an in-line fuse holder for modern flat fuses, only bigger.
It has a green/brown wire and the green compressor wire as inputs, and
has
plastic clips to retain the item which is plugged into it.

The part is still plugged into mine, but the plastic cover over it is
60%
missing, leaving the fuse(?) exposed to the elements. The holder itself
is fine, it’s just the item being held which is broken.

Is this in fact the (50A?) a/c compressor fuse? And (either way), can I
replace it with an OTC part, or must this item be prescribed by the
Lords
of Lucas?

(The a/c works great, but…)

–

  • bill
    '84 XJ6 (Julia)

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24

Chuck Renner wrote:

What are “INFRARED THERMOMETERS”? Never even knew they
existed!! Can they measure temps INSIDE the, say,
THERMOSTAT HOUSING without the need to probe inside it
or open it up? Please give me known brand names if
possible -unless you happen to know a specialized
store here in Madrid!!!

Yago, they don’t let you see inside something, but rather allow you to
remotely read the surface temperature of an object. You simply aim the
thermometer at what you want to read, and it tells you the temperature.

It’s a bolometer, Chuck - and “from the distance of yards you can
measure the temperature of a polar bears a…” Which is sometimes
useful…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)===================================================
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25

Not a bad suggestion Alex, but I checked this too. The thermostat is a
clone of the Waxstat brand. The unit is the correct type, purchased from
my local Jag parts house.

Thanks for the welcome Yago, but I have had the car for about two years
now, and this is the first time it has started to overheat while there
is actually sufficient coolant in the engine. Refer to my previous post
for the saga. :slight_smile:

Oh and Maynard, the belt is at the correct tension, it is most
definitely not an issue with slippages.

I am in the process of playing the ‘waiting game’ for when I have some
free time to get the car flow tested, but as soon as I figure out what
is the problem, I will reveal it here.

Cheers!

Grant Watson

1984 XJ6 Series III
- In Western Sydney, Oz.===================================================
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26

This is the thermal limit fuse switch used on the early XJ6 A/C
systems with a Superheat switch.

Thanks, gentlemen! I’ve already got some parts on order at CW; I’ll see
if I can replace this when I’m down picking them up. (Greg?)

You didn’t mention the third wire. It’s a black wire with a
white connector that attaches to the Superheat switch on the back of the
A/C compressor.

I didn’t realize there was a black wire there. Went back out and
looked, and sure enough, almost completely hidden by the harness is the
third wire.

I think what I really need is three-dimensional parts and service manuals,
similar to what they’ve developed for e.g. aircraft building and
maintenance, with a heads-up display via goggles. :-)–

  • bill
    '84 XJ6 (Julia)

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27

So, we may then be looking at a small head gasket leak on the exhaust side of
things. Has there been any loss of coolant out the pressure cap? Can you
have a test done to see if the coolant has exhaust products in it? HAve you
tried torquing the head nuts down a bit more?–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

Grant Watson wrote:

Not a bad suggestion Alex, but I checked this too. The thermostat is a
clone of the Waxstat brand. The unit is the correct type, purchased from
my local Jag parts house.

Thanks for the welcome Yago, but I have had the car for about two years
now, and this is the first time it has started to overheat while there
is actually sufficient coolant in the engine. Refer to my previous post
for the saga. :slight_smile:

Oh and Maynard, the belt is at the correct tension, it is most
definitely not an issue with slippages.

I am in the process of playing the ‘waiting game’ for when I have some
free time to get the car flow tested, but as soon as I figure out what
is the problem, I will reveal it here.

===================================================
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28

Thanks a lot, Will “et alii,” for the info on INRARED
THERMOMETERS… great toys they are, but -after
reading your explanations on them- I don’t hink this
is what I was looking for, really.

Cheers to all,

YC -Madrid, SPAIN
1975 4.2L SII XJ6
Regency red/beige— William Watson cars@thekid.com wrote:

Yago, you should be able to find infrared
thermometers on your favorite
search engine - they’ve become quite common in the
past few years. They
use a laser beam for an aim point, and give the
average surface temp for
the surface at which they are aimed. (They are
affected by the type of
service - i.e. its heat reflectivity - and the
distance between the
surface and the thermometer - a greater distance
gives a larger spot
size.)

=====
“Alive at every moment… why not?”

Do you Yahoo!?
The New Yahoo! Shopping - with improved product search

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29

"from the distance of yards you can

measure the temperature of a polar bears a…" Which is sometimes
useful…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

G’day Frank,
Much safer than trying to insert a thermometer I reckon. :slight_smile:
Regards,
John Hudson
Brisbane Australia
71 XJ6 SI
85 XJ6 SIIIOn Fri, 17 Oct 2003 21:56:50 +1300, you wrote:

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30

John Hudson wrote:>On Fri, 17 Oct 2003 21:56:50 +1300, you wrote:

"from the distance of yards you can

measure the temperature of a polar bears a…" Which is sometimes
useful…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

G’day Frank,
Much safer than trying to insert a thermometer I reckon. :slight_smile:

I like your concern for the safety and comfort of polar bears, John…:slight_smile:

Frank
xj6 85 Sov Europ (UK/NZ)

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31

So, we may then be looking at a small head gasket leak on the exhaust

side of things. Has there been any loss of
coolant out the pressure cap?

I highly doubt that it is a gasket leak, as the head gasket was replaced
in early '02. There is no coolant disappearing at all, anywhere in the
system - that problem was rectified some time ago. This recent
overheating problem appeared suddenly, and about the same time I picked
the car up from having the transmission overhauled, though I don’t see
any obvious link between these two events.

Cheers!

Grant Watson
1984 XJ6 Series III
- In Western Sydney, Oz.===================================================
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32

In reply to a message from Grant Watson sent Sat 18 Oct 2003:

Does your transmission cooler run through the radiator? Have they
drained the rad or removed it to service the trans? I guess not,
although they will have disturbed those hoses I’m sure for the
trans cooler. Maybe an air lock issue. There is quite a section on
how to fill/drain cooling systems on the X300 at any rate on the CD
ROM and running with heaters/on off at the time of emptying/filling
etc. Could be an airlock.

On the other hand I was convinced that since your engine temp
responds quickly above idle and is OK out on the road, all the
major components are OK and it may just be a sender or gauge
malfunction, since one would expect higher heat at stationary
conditions. And since it is designed to run pressurised, 105 is
high but not impossibly so. Does it fill the overflow tank? I.e.
blow out coolant (albeit taking it back later) at these ‘high’
temps? If it doesn’t blow into the header tank or past the rad cap
then maybe it’s not really high after all? If the rad cap spring is
weak it may blow off too low, or maybe they switched caps at the
trans place?

Thing is, you said the engine misbehaves so it does sound as if the
temp is genuinely going high and it’s not just a sudden gauge or
sender issue.

Hope you get it sorted!–
Peter Crespin 94 X300 Daimler / 66 2+2 ‘E’
Buxton, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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33

Did you ever solve your overheating problem?

My vote is the water pump has worn allowing some ‘‘cavitation’’ or
bubbling and foaming that sorts itself out with higer revs…

No I didn’t solve the problem yet. It hasn’t been that much of an issue
lately since I haven’t been driving into Sydney city each day (80km’s
each way) and as such haven’t been caught in traffic much. I have,
however, been far too busy to get into it and pull off the water pump.
Maybe after Christmas I will be able to find the time.

My thoughts do lie with the water pump. By the corrosion in the water
rail and thermostat housing, I would say that the car has been run
without corrosion inhibiting coolant for some significant time, so I
thought that the water pump may have been blocked up with corrosion or
something similar.

I guess ill find out sooner or later.===================================================
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34

In reply to a message from Grant Watson sent Mon 15 Dec 2003:

Guys, although I’m eager and open minded to pick up findings about
causes for various tehcnical (Jag) problems, this one sounds like a
long shot.

My experience is that a non-leaking and freely rotating waterpump
can only have degraded funktion if one or more impeller segments
are broken off. A waterpump worn or corroded to the point that
funktion is affected would be a new one for me, anyone have 1’st
hand proof?? (I’m not talking about high revving race engines) If
so I will gladly store it mentally for future trouble-shootning,
but until then…I’m doubtful :slight_smile:

Goran…–
The original message included these comments:

My vote is the water pump has worn allowing some ‘‘cavitation’’ or
bubbling and foaming that sorts itself out with higer revs…

–
XJ6 S1 1970 2.8 (4.2) MOD , Triumph TR 6 PI 1971,
Jarfalla, Sweden
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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35

A waterpump worn or corroded to the point that
funktion is affected would be a new one for me, anyone have 1’st
hand proof?? (I’m not talking about high revving race engines) If
so I will gladly store it mentally for future trouble-shootning,
but until then…I’m doubtful :slight_smile:

Never say never Goran… I could have the first example. :slight_smile: Only time
will tell, but the water pump is the only component in the cooling
system which hasn’t been replaced or overhauled, so I am led to believe
there is a fault with it somehow.

I guess all will be revealed when I take the pump off after Christmas.

Cheers!

Grant Watson

1984 XJ6 Series III
- In Western Sydney, Oz.===================================================
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36

Grant, bite the bullet and put in an electric water pump. That (plus, maybe,
electric fans) will definitely do the trick.

Fazal
MEL/Oz
82 XJ6
www.jonat.org----- Original Message -----
From: “Grant Watson” dopefish@boztek.com.au

No I didn’t solve the problem yet. It hasn’t been that much of an issue
lately since I haven’t been driving into Sydney city each day (80km’s
each way) and as such haven’t been caught in traffic much. I have,
however, been far too busy to get into it and pull off the water pump.
Maybe after Christmas I will be able to find the time.

My thoughts do lie with the water pump.

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37

Grant, bite the bullet and put in an electric water pump. That (plus,
maybe,
electric fans) will definitely do the trick.

Maybe for some Fazal, but not for this little black duck. It used to
work just fine in the hottest of hot weather, so I want to get it
sorted. Besides, I think the electric fans make too much noise when
engaged.

Cheers!

Grant Watson

1984 XJ6 Series III
- In Western Sydney, Oz.===================================================
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38

In reply to a message from Grant Watson sent Mon 15 Dec 2003:

Grant, HaHa, you’re spot on, I’ve been ‘‘absolutly certain’’ far too
many times in the past, that’s why I tried to express myself as
vague as possible. Humble-Pie never tastes good.

Now to your overheating. If your pump looks OK, maybe you have to
approach this ‘‘from the other side’’ iow. The cooling system is fine
but the engine is generating too much heat?? Any things replaced,
repaired, tuned or other things happening to the engine prior to
heating problem surfaced?

Goran…–
The original message included these comments:

Never say never Goran… I could have the first example. :slight_smile: Only time
will tell, but the water pump is the only component in the cooling
system which hasn’t been replaced or overhauled, so I am led to believe
there is a fault with it somehow.
I guess all will be revealed when I take the pump off after Christmas.

–
XJ6 S1 1970 2.8 (4.2) MOD , Triumph TR 6 PI 1971,
Jarfalla, Sweden
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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39

Grant, while not trying to get you to go electric, efans do make much less
noise than the OE mechanical one. Sometimes people put in far too big a fan
or fans and that contributes to unnecessary noise as well. And, if the fans
are controlled to be able to go on after the car is parked, which is the right
way to do it, then fan speed can and should be reduced to match the lower rate
of coolant flow from the stopped engine – this makes the fan(s) almost
inaudible. I agree that hearing an efan running full tilt at the front grille
of a parked Mercedes or Jetta can be annoying! Both our XJs are electric and
you’ll never notice that.–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

Grant Watson wrote:

Grant, bite the bullet and put in an electric water pump. That (plus,
maybe,
electric fans) will definitely do the trick.

Maybe for some Fazal, but not for this little black duck. It used to
work just fine in the hottest of hot weather, so I want to get it
sorted. Besides, I think the electric fans make too much noise when
engaged.

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40

Grant, given what you say about the corrosion evidence, why not think that the
radiator needs a good rodding out?–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

Grant Watson wrote:

Did you ever solve your overheating problem?

My vote is the water pump has worn allowing some ‘‘cavitation’’ or
bubbling and foaming that sorts itself out with higer revs…

No I didn’t solve the problem yet. It hasn’t been that much of an issue
lately since I haven’t been driving into Sydney city each day (80km’s
each way) and as such haven’t been caught in traffic much. I have,
however, been far too busy to get into it and pull off the water pump.
Maybe after Christmas I will be able to find the time.

My thoughts do lie with the water pump. By the corrosion in the water
rail and thermostat housing, I would say that the car has been run
without corrosion inhibiting coolant for some significant time, so I
thought that the water pump may have been blocked up with corrosion or
something similar.

===================================================
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