Maybe this is a lead as to why it runs better after warmed
up.
I’ve been in denial, thinking - no way can it be
mechanical. The head gasket has about 70,000 on it,
because of the HP it has at WOT…it can’t be mechanical.
Well this morning I did a compression test and here are the
numbers.
6 - 151
5 - 149
4 - 148
3 - 75 >100
2 - 127
1-123
Not good numbers.
The plugs looked fine and I don’t think I’m using coolant.
Well I did have to put a little less than a quart of
coolant in the tank this summer.
My SIII died in August and now the XJ40 is dying in
August.–
John 90 XJ40
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from John S sent Sun 10 Aug 2008:
John,
No, numbers are not good.
Engine warm? Wide open throttle?
Any improvement when you added a spoon-full of oil to the
bad cylinders and tried again? If not, probably a burned
exhaust valve or three or blow-by between the first three
cylinders.–
The original message included these comments:
Well this morning I did a compression test and here are the
numbers.
6 - 151
5 - 149
4 - 148
3 - 75 >100
2 - 127
1-123
Not good numbers.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Are those numbers from a fully warmed up engine?----- Original Message -----
From: “John S” js4453@att.net
To: xj40@jag-lovers.org
Sent: Sunday, August 10, 2008 9:05 AM
Subject: [xj40] Compression - It was running at about 98% efficiency
Maybe this is a lead as to why it runs better after warmed
up.
I’ve been in denial, thinking - no way can it be
mechanical. The head gasket has about 70,000 on it,
because of the HP it has at WOT…it can’t be mechanical.
Well this morning I did a compression test and here are the
numbers.
6 - 151
5 - 149
4 - 148
3 - 75 >100
2 - 127
1-123
Not good numbers.
The plugs looked fine and I don’t think I’m using coolant.
Well I did have to put a little less than a quart of
coolant in the tank this summer.
My SIII died in August and now the XJ40 is dying in
August.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Dave sent Sun 10 Aug 2008:
Numbers are from a fully cold engine. I don’t like
rrmoving spark plugs from a warmed up engine.–
John 90 XJ40
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from John S sent Sun 10 Aug 2008:
John,
Well, you should do the test again on a warm engine with the
throttle held wide open and a good battery to spin the
engine (sans plugs) at at least 300 RPM both ‘dry’ and ‘wet’
before deciding if the numbers are that bad.
You should see around 160 psi with a max of 10 psi
difference between cylinders.–
The original message included these comments:
Engine was not warm. It was not WOT.
It was a dry test…no oil.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Bryan N sent Sun 10 Aug 2008:
I had all plugs removed when I did the test. I can’t
remember the protocol for compression testing. Should all
plugs be out?
I’ll try again tomorrow. Because of the aluminum threads,
I always worry about removing or installing plugs in a warm
engine.–
John 90 XJ40
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Compression tests don’t tell you much from a cold engine. I’ve seen numbers
like that from a cold engine which are perfect when the engine is at
operating temperature.
If you are worried about removing the plugs on a warm engine remove them
when cold, clean them up perfectly and ensure they have anti seize. Then
tighten just snug. Then warm up the engine. Removal should be no problem.----- Original Message -----
From: “John S” js4453@att.net
To: xj40@jag-lovers.org
Sent: Sunday, August 10, 2008 11:58 AM
Subject: Re: [xj40] Compression - It was running at about 98% efficiency
In reply to a message from Dave sent Sun 10 Aug 2008:
Numbers are from a fully cold engine. I don’t like
rrmoving spark plugs from a warmed up engine.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from John S sent Sun 10 Aug 2008:
John,
Yes, all plugs should be out - otherwise you won’t spin the
engine fast enough to get a proper reading.
Having the throttle wide open will also automatically cut
off the injector pulses so you should not flood the engine.–
The original message included these comments:
I had all plugs removed when I did the test. I can’t
remember the protocol for compression testing. Should all
plugs be out?
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Bryan N sent Sun 10 Aug 2008:
Thanks
Today I will do it WOT on a hot engine. As suggested I
will only snug the plugs probably a hard-hand-tightening.–
The original message included these comments:
Having the throttle wide open will also automatically cut
off the injector pulses so you should not flood the engine.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !