[xk] What Level Does Your Coolant Seek? and:Compression Test Result

XK
1

Last summer the coolant level of my XK140, when cold,
seemed to always seek a level about 1/2’’ above the tops of
the cooling tubes, visible in the top radiator tank when the
rad cap is removed

This summer, the coolant, when cold, now all of a sudden
likes to seek a level somewhere below the tops of the tubes.
Not sure exactly how much below the tops of the tubes,
because the coolant level cant then be seen. But probably
not too far below the tops of the tubes, because when
warming up coolant quickly rises and can be seen (with rad
cap off) circulating well above the tubes. Then when cold,
it returns to the level somewhat below the tops of the tubes

At first, because of the now lower level, I thought I was
probably loosing coolant somewhere, but with no visible
external leaks, I then began thinking blown head gasket

A few times I was pretty worried about the head gasket, and
even removed the plugs, after the car had been sitting a few
days, and then cranked the engine over, expecting to see the
disappointing sight of coolant shooting out of one of the
plug holes. Luckily nothing liquid shot out of the plug
holes, and I am now not worrying too much, anymore, about a
rod bending hydraulic lock

It would be fun to know how everyone elses cooling systems
behave, so…what level does anyones coolant tend to seek,
when your XK engine is cold ? Thanks in advance for any info

During one of the episodes of removing plugs and expecting
to see a geyser of water shoot out a plug hole, I finally
got up enough courage to do a compression test on the
faithful old Jag engine

I have deliberatly not done a compression test on this
engine in recent history. The reason being, I just didnt
want to be disappointed by knowing about shot rings etc.
This car had been hibernating, and the engine unstarted, for
28 years (1974 - 2002), before reactivation about three
years ago.
The engine starts almost instantly, runs strongly, good oil
pressure, valve lash ok, doesnt overhest, with no major
problems (except for oil leaks), so I selfishly just didnt
want to learn any bad news about shot rings, until I have
had some fun driving the car around for a while

Well, anyway, here are the compression test results, the
engine being cold, all plugs removed, a short hunk of 2x4
wood placed between the flat face of the pancake filter on
the rear carb and the rear throttle return spring lever to
hold the throttle almost completely open: #1 through #6 (the
#1 being the #1 at the rear of the engine)

165, 175, 155, 170, 172, 181 psi

Somewhat better than I had actually expected, but #3 is a
little low. Possibly a glazed cylinder wall on #3? The
engine is a normal 8:1 XK140 engine, but the cylinder head
had been milled a bunch back in the old days before the car
was laid up, in an effort (popular, at the time) to increase
compression ratio for, what else, more power to run faster!

Anyhow, back to my question: what level does your coolant
like to seek (engine cold) Thanks–
Gary Grant S818919DN
Ottawa, Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

2

Gary,

Sounds like you did a cold dry test here. Try taking readings when the
engine is warm and also do a “wet” test (shoot a few squirts of 30wt. in
each bore before each test. You might even find that your lower cylinder
reading is due to a slight valve problem (too tight). The wetting should
help determine if it is bore to ring sealing.

Regards,

Rick

3

What is the best way to test an engine for head gasket problems during a
pre purchase inspection? I am looking at a low mileage car that sat for a
long time with a the engine
pickled for storage. It has since been resurrected for about 2 years.
Would a leak down test be the best way? And for this check would it be
better to be done hot or cold? Or, is there a much better way?

— Dennis Molnar
— @Dennis_Molnar
— EarthLink: The #1 provider of the Real Internet.

[Original Message]
From: Gary Grant grant3@sympatico.ca
To: xk@jag-lovers.org
Date: 6/17/2006 2:29:40 AM
Subject: [xk] What Level Does Your Coolant Seek? and:Compression Test
Result>
Last summer the coolant level of my XK140, when cold,
seemed to always seek a level about 1/2’’ above the tops of
the cooling tubes, visible in the top radiator tank when the
rad cap is removed

This summer, the coolant, when cold, now all of a sudden
likes to seek a level somewhere below the tops of the tubes.
Not sure exactly how much below the tops of the tubes,
because the coolant level cant then be seen. But probably
not too far below the tops of the tubes, because when
warming up coolant quickly rises and can be seen (with rad
cap off) circulating well above the tubes. Then when cold,
it returns to the level somewhat below the tops of the tubes

At first, because of the now lower level, I thought I was
probably loosing coolant somewhere, but with no visible
external leaks, I then began thinking blown head gasket

A few times I was pretty worried about the head gasket, and
even removed the plugs, after the car had been sitting a few
days, and then cranked the engine over, expecting to see the
disappointing sight of coolant shooting out of one of the
plug holes. Luckily nothing liquid shot out of the plug
holes, and I am now not worrying too much, anymore, about a
rod bending hydraulic lock

It would be fun to know how everyone elses cooling systems
behave, so…what level does anyones coolant tend to seek,
when your XK engine is cold ? Thanks in advance for any info

During one of the episodes of removing plugs and expecting
to see a geyser of water shoot out a plug hole, I finally
got up enough courage to do a compression test on the
faithful old Jag engine

I have deliberatly not done a compression test on this
engine in recent history. The reason being, I just didnt
want to be disappointed by knowing about shot rings etc.
This car had been hibernating, and the engine unstarted, for
28 years (1974 - 2002), before reactivation about three
years ago.
The engine starts almost instantly, runs strongly, good oil
pressure, valve lash ok, doesnt overhest, with no major
problems (except for oil leaks), so I selfishly just didnt
want to learn any bad news about shot rings, until I have
had some fun driving the car around for a while

Well, anyway, here are the compression test results, the
engine being cold, all plugs removed, a short hunk of 2x4
wood placed between the flat face of the pancake filter on
the rear carb and the rear throttle return spring lever to
hold the throttle almost completely open: #1 through #6 (the
#1 being the #1 at the rear of the engine)

165, 175, 155, 170, 172, 181 psi

Somewhat better than I had actually expected, but #3 is a
little low. Possibly a glazed cylinder wall on #3? The
engine is a normal 8:1 XK140 engine, but the cylinder head
had been milled a bunch back in the old days before the car
was laid up, in an effort (popular, at the time) to increase
compression ratio for, what else, more power to run faster!

Anyhow, back to my question: what level does your coolant
like to seek (engine cold) Thanks

Gary Grant S818919DN
Ottawa, Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–