How do you do a compression test and a leak-down test?
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St. Jude Donor '03-'04
Cruise-In 1-2-3-4-5 Veteran
How do you do a compression test and a leak-down test?
...on the car?
I have a cheap compression gauge, from NAPA over the counter, it's terminated in a bare rubber hose.
So how do you do a compression check and a leak-down check while the engine is still in the car and hooked up? Can you do this?
~Matt W.
I have a cheap compression gauge, from NAPA over the counter, it's terminated in a bare rubber hose.
So how do you do a compression check and a leak-down check while the engine is still in the car and hooked up? Can you do this?
~Matt W.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: How do you do a compression test and a leak-down test? (Matt Black)
wow... that is a cheap compression tester.
you need a tool for the leak down. you can buy one, or, there are plans that were posted real recent.
a compression tester needs a fitting so it can be screwed into the sparkplug hole. start the motor, 4 cranks or so... and read the gauge.
for a leakdown test, the special tool will go in just like a compression tester, but will have a fitting for an air compressor... add pressure, don't remember how much - sorry - and watch the cylinder loose said pressure. the cylinder must be at TDC for it to work...
the leakdown is the better test... it reflects the real problems...
others, I am sure will fill in the huge gaps.
you need a tool for the leak down. you can buy one, or, there are plans that were posted real recent.
a compression tester needs a fitting so it can be screwed into the sparkplug hole. start the motor, 4 cranks or so... and read the gauge.
for a leakdown test, the special tool will go in just like a compression tester, but will have a fitting for an air compressor... add pressure, don't remember how much - sorry - and watch the cylinder loose said pressure. the cylinder must be at TDC for it to work...
the leakdown is the better test... it reflects the real problems...
others, I am sure will fill in the huge gaps.
Drifting
Joined: Feb 2000
Posts: 1,994
Likes: 0
From: Charleston, WV
Re: How do you do a compression test and a leak-down test? (bogus)
You need a compression guage that will screw into the plug hole. remove ALL the spark plugs, Dissable the ignition system.....(unplug the power wire from the dist cap) ,........dissable the fuel pump (pull the fuse) ........ screw the guage into each cylinder and crank the engine 5 times for each cylinder. You will want a reading between 150 and 180 and all readings should be within 25% from thenhighest to the lowest.
Now to do a leakdown ............ first you have to have an aircompressor that will pump at least 100 psi ........more is better. you will need a cylinder leakage tester which is a guage that has a regulator. you can make one but that's another story. pull all the plugs (if they're not already out from the compression test) remove the radiator cap (safety precaution) and each cylinder you want to test will need to be at top dead center on the compression stroke (both valves closed). You will the screw a hose into the plug hole much like the compression test. You will pressurise the cylinder and read the guage. (sorry I didn't tell you how to calibrate the guage) . the reading will give you a percent of leakage. if you hear ait leaking , listen to find out where it is coming from.........intake would be a leaky intake valve, exhaust pipe .......and exhaust valve, crankcase ..... bad rings or a hole in the piston, ......... if it blows water out of the radiator you have a cracked head or blown head gasket......... you took the cap off the radiator because the cooling system isn't made to handle 100+ psi.....
this will be enough info to make you dangerous....... if you need or want more e-mail me.......hope that helps :yesnod:
Now to do a leakdown ............ first you have to have an aircompressor that will pump at least 100 psi ........more is better. you will need a cylinder leakage tester which is a guage that has a regulator. you can make one but that's another story. pull all the plugs (if they're not already out from the compression test) remove the radiator cap (safety precaution) and each cylinder you want to test will need to be at top dead center on the compression stroke (both valves closed). You will the screw a hose into the plug hole much like the compression test. You will pressurise the cylinder and read the guage. (sorry I didn't tell you how to calibrate the guage) . the reading will give you a percent of leakage. if you hear ait leaking , listen to find out where it is coming from.........intake would be a leaky intake valve, exhaust pipe .......and exhaust valve, crankcase ..... bad rings or a hole in the piston, ......... if it blows water out of the radiator you have a cracked head or blown head gasket......... you took the cap off the radiator because the cooling system isn't made to handle 100+ psi.....
this will be enough info to make you dangerous....... if you need or want more e-mail me.......hope that helps :yesnod:
