water is coming from under the filler cap - the one on the cross
pipe - I bought a new cap but to no avail - its coming out even
though the temp indicator needle has not even risen half way to the
N
any ideas guys ?
[bloody britsh cars - I ask you ]
Denc–
88 xjs v12 convertible
Nice, France
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I bought a new cap but to no avail - its coming
out even though the temp indicator needle has not even risen
If it’s a direct replacement cap and still leaking, could the mouth of the
pipe be bent?
Gordon
'88 XJ-SC (Lucas CEI) Bagheera (49,000 miles)
http://www.myjags.net
Alexandria, VA US
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In reply to a message from Gordon Vivace sent Sun 29 May 2005:
I guess - but what could have bent it like that ? - it seems as it
was - I thought that having sorted out the in wing resevoir any
excess pressure in the system would expand into that and not force
its way our through thr cap - having blown no end of cooling pipes
in the car it seems to me the cooling system is excessively
pressurised - I changed the thermostats lat year [88 degree ones
which I do intend to change for the 80 degree ones ] I would be
surprised if one had quit already - they had jiggle pins and I put
them uppermost as advised - I am really confused now
Denc–
88 xjs v12 convertible
Nice, France
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I guess - but what could have bent it like that ?
In my experience? Only a mechanic 
Gordon
'88 XJ-SC (Lucas CEI) Bagheera (49,000 miles)
http://www.myjags.net
Alexandria, VA US
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blown head gasket… better run a pressure test.
sorry Denc
–Harold
it seems to me the cooling system is excessively
pressurised - I changed the thermostats lat year [88 degree ones
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In reply to a message from Harold Robertson sent Sun 29 May 2005:
Listen to the rad after shutting off the car, once up to temp.
Listen for gurgling noises. I agree with Harold. Sounds like there
is compression getting into the cooling system. Fingers crossed
over here.–
Rob Wade
Windsor Ontario, Canada
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In reply to a message from Rob Wade sent Sun 29 May 2005:
Thenks guys - [I think ]
I checked the oil and I can see no sign of water in it - would
there be ?
And if there is presuure like that why does it not blow the coolant
out into the expansion tank ?
Denc–
88 xjs v12 convertible
Nice, France
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Have you got the correct type of cap on it?
The cross pipe shouldn’t blow out coolant. That’s the job of the pressure
cap on the expansion tank. A plain sealed cap is all that’s needed on the
cross pipe, but they can be hard to find. Many people fit a pressure cap
but it must have a rubber sealing washer under the TOP part of the cap, NOT
stainless spring rings as they will not seal. Alternatively, a higher
pressure release cap than the expansion tank cap could be fitted.
Regards,
Paul.
Paul’s Daimler Diary:-
http://www.pclarkson.plus.com/
How you can save money on so many things:-
http://www.payless4-things.com-----Original Message-----
From: owner-xj-s@jag-lovers.org [mailto:owner-xj-s@jag-lovers.org]On
Behalf Of denc
water is coming from under the filler cap - the one on the cross
pipe - I bought a new cap but to no avail - its coming out even
though the temp indicator needle has not even risen half way to the
N
any ideas guys ?
[bloody britsh cars - I ask you ]
Denc
Ahem! maybe it's the people looking after them?
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In my one experience with a blown head gasket (not in a Jag), the oil on the
dipstick appeared a light brown color and frothy, thick with tiny bubbles.
What is the pressure on the cap on the radiator - is it higher pressure than
the stock spec? Sorry I am not near my car to check the pressure rating.
Steve S.
Lexington, MA USA
'91 xj-s v12 coupe----- Original Message -----
From: “denc” den@csy.co.uk
To: xj-s@jag-lovers.org
Sent: Sunday, May 29, 2005 5:55 PM
Subject: Re: [xj-s] After aqll my efforts the overheating has returned
.arrggghhh
In reply to a message from Rob Wade sent Sun 29 May 2005:
Thenks guys - [I think ]
I checked the oil and I can see no sign of water in it - would
there be ?
And if there is presuure like that why does it not blow the coolant
out into the expansion tank ?Denc
–
88 xjs v12 convertible
Nice, France
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A blown head gasket can be:
Oil in the water (you can usually see it in the radiator)
Oil in the combustion chamber (very unlikely, engine smokes, usually
diagnosed as rings and usually is)
Water in the oil (thick foamy sludge on the dipstick – reading very
high)
Water in the combustion chamber (poor running, steam out the tailpipe,
very clean combustion chamber when viewed through a spark plug hole)
Combustion gasses in the water jacket (high radiator pressure – you
may even see bubbles - coolant blows out the path of least resistance)
Combustion gasses in the crankcase (unusual, but can cause a crankcase
fire)
Water leaking to the outside of the engine (confirmed by visual
inspection)
Oil leaking to the outside of the engine (confirmed by visual
inspection)
Combustion gasses leaking to the outside of the engine (very unlikely
due to engine design)
After checking the oil level, I would put a pressure tester on the
cooling system and check that it holds pressure to specs. After
correcting any leaks, I would then start the engine with the pressure
tester still connected and warm the engine up and see how it reacts.
Obviously, pressure that won’t stop rising suggests a problem.
–HaroldOn May 29, 2005, at 6:02 PM, stephen sarmanian wrote:
In my one experience with a blown head gasket (not in a Jag), the oil
on the
dipstick appeared a light brown color and frothy, thick with tiny
bubbles.
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If you suspect combustion gas leaking into the water
jacket, buy or borrow a block checking kit.
The greenish/yellow liquid in the checker turns deep
blue in the presence of those gasses. Takes about
three minutes and I have never seen it mis-diagnose.
Tom Wilson
…where shall I go, now that I’ve gone too far…__________________________________
Do you Yahoo!?
Yahoo! Small Business - Try our new Resources site
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For the benefit of the archives.
Happily Denc’s problem was solved by sorting out the radiator caps on the
cooling system.
A plea to all those who find a cure to their problems, please make a posting
(under the original thread subject) stating how the situation was resolved
for the benefit of those that follow. Thank you 
Regards,
Paul.
Paul’s Daimler Diary:-
http://www.pclarkson.plus.com/
How you can save money on so many things:-
http://www.payless4-things.com
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In reply to a message from Paul Clarkson sent Mon 30 May 2005:
Paul
You are right I should have posted the outcome here
Thnaks for your guidance towards a problem with the cap
It had no rubber ring and I think it was too short to reach down to
the ledge that runs around the filler pipe as it narrows - where
the rubber seal on the bottom of the cap is supposed to fit
Thge exact solution was to put an o ring around the top of the cap
and to place a couple of o rings on the ledge inside and around the
pipe All of these came from French domestic plumbing systems [
which for your interest are still done in inches whereas the UK is
now metric] I was amazed they fitted so well.
So far its perfect.
Denc–
88 xjs v12 convertible
Nice, France
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Denc,
You shouldn’t need the two O rings on the ledge. If excessive pressure
builds up, where’s it going to escape beyond the pressure seal? The answer
is from under the top of the cap (if it isn’t sealed properly).
There is no expansion overflow in the filler neck - see 5th. photo down on
this page: http://www.jag-lovers.org/xj-s/book/CrossoverPipe.html
The expansion overflow is dealt with by the expansion tank cap. That cap
has an excessive pressure overflow pipe either to a catch bottle under the
front wing, or to the environment, depending on which model you have.
So, to sum up. The cap on the cross-pipe doesn’t regulate pressure. The
spring and washer that seals on the ledge inside the filler neck is
superfluous - a plain cap or lid used to be fitted as OEM (chained to the
filler neck), but now difficult to obtain, so just make sure you have a
rubber seal under the very top part of the cap.
As an aside, I had a normal cap with a rubber top seal, but it leaked
slightly where the rivet holding the spring went through the cap. I drilled
it out and chucked the spring. I soldered a piece of brass over the hole
and everything’s fine.
Regards,
Paul.
Paul’s Daimler Diary:-
http://www.pclarkson.plus.com/
How you can save money on so many things:-
http://www.payless4-things.com-----Original Message-----
From: owner-xj-s@jag-lovers.org [mailto:owner-xj-s@jag-lovers.org]On
Behalf Of denc
Paul
Thnaks for your guidance towards a problem with the cap
It had no rubber ring and I think it was too short to reach down to
the ledge that runs around the filler pipe as it narrows - where
the rubber seal on the bottom of the cap is supposed to fit
Thge exact solution was to put an o ring around the top of the cap
and to place a couple of o rings on the ledge inside and around the
pipe All of these came from French domestic plumbing systems [
which for your interest are still done in inches whereas the UK is
now metric] I was amazed they fitted so well.
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In reply to a message from Paul Clarkson sent Tue 31 May 2005:
Paul
Yep - I see that you are right - I just wanted to stop the leak
and if it needed both the belt and the braces well so be it.
btw - I visited your site - very impressive and a lovely lovely car
you have there [ though I think your garage should be modelled on
on Mr Emdens [ did I get thet right ] in Florida
Both of you are brilliant, knowlegable, talented , generous and mad
as march hares - good on yers - we are all grateful
Denc–
88 xjs v12 convertible
Nice, France
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