I’m planning to perform a compression test. I’ll probably go rent
the kit from Autozone or similar place. However, I’ve never done
or seen a compression test carried out, so I don’t know much. My
guess is that I need to disconnect the distributor cable that goes
to the coil. Next, find the relay or fuse for the fuel pump.
Remove each of the spark plug, hook the compression test up, and
crank the engine a few times. Record the reading on paper. Repeat
the proces for other cylinders. I suppose cylinders are
independent of each other so I don’t have to put back spark plug #1
once I move one to #2.
Am I accurate? Please provide me any tips you might have.
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In reply to a message from QuangXJ40 sent Fri 24 Mar 2006:
You’ve got the basics. What I do is to remove all of the spark
plugs for the test (engine spins freely and faster that way). I
haven’t bothered with coil wires or fuel relay.
With all of the spark plugs out, you can easily tell from the sound
when the cylinder being tested is on its compression stroke. I
stop cranking after 6 compressions and write down the pressure,
then move to the next cylinder.
While you’re under the hood (bonnet), check the intake manifold
bolts for tightness (10 and 13 mm wrenches) and thoroughly inspect
any hose that connects to the intake manifold for cracks. Also
inspect the injectors for leaking fuel.
If you have one cylinder with significantly lower pressure than the
others, it’s most likely a burned exhaust valve.
You can also do a ‘wet’ compression test to assess the performance
of the piston rings after you do the ‘dry’ test. Squirt some motor
oil into the spark plug holes then run a compression test again.
Squirt the oil in just before you attach the gauge. Crank the
engine for the same number of compressions as you did for the ‘dry’
test. The oil will temporarily seal any imperfections in the rings
during the ‘wet’ test. Comparing the ‘wet’ and ‘dry’ numbers will
give an indication of how ‘bad’ the rings are.–
The original message included these comments:
Remove each of the spark plug, hook the compression test up, and
crank the engine a few times. Record the reading on paper. Repeat
the proces for other cylinders. I suppose cylinders are
independent of each other so I don’t have to put back spark plug #1
once I move one to #2.
Am I accurate? Please provide me any tips you might have.
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In reply to a message from Jaguarpete sent Fri 24 Mar 2006:
you should pull the high tent lead from the dist, to ground and 3
comp stroke is enough . other then that you got it. pajtas–
jaguarjoe 54 XK 120 rdstr 1961 MKIX 94 XJ6
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In reply to a message from Jaguarpete sent Fri 24 Mar 2006:
Thanks for your reply. It’s quite informative.
I remmeber tightening the intake manifold a few years back. I was
surprised to find that the intake manifold was so loose. I will
try to tighten the bolts again. I’m not sure how to inspect the
injectors for leaking fuel. I suppose if they leak I can smell the
fuel odor.
Thanks.–
The original message included these comments:
While you’re under the hood (bonnet), check the intake manifold
bolts for tightness (10 and 13 mm wrenches) and thoroughly inspect
any hose that connects to the intake manifold for cracks. Also
inspect the injectors for leaking fuel.
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You need to remove the fuse to the pump and let the engine run until the
fuel is used up
Hook the battery up to a power booster used to jump start to insure you
have good steady power for all plugs
Remove all the plugs
Insert the tester in one hole
Crank engine at 300 rpm continuously until you get a good steady reading
Repeat
Good Luck
Jay 90 VDP Majestic
QuangXJ40 wrote:
I’m planning to perform a compression test. I’ll probably go rent
the kit from Autozone or similar place. However, I’ve never done
or seen a compression test carried out, so I don’t know much. My
guess is that I need to disconnect the distributor cable that goes
to the coil. Next, find the relay or fuse for the fuel pump.
Remove each of the spark plug, hook the compression test up, and
crank the engine a few times. Record the reading on paper. Repeat
the proces for other cylinders. I suppose cylinders are
independent of each other so I don’t have to put back spark plug #1
once I move one to #2.
Am I accurate? Please provide me any tips you might have.
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 !