Leak down test? and getting pistons to TDC?
#1
Leak down test? and getting pistons to TDC?
Alright guys I have a few questions on performing a leak down test and would like to get them cleared up before I attempt to perform one.
1.) What is the easiest way of getting each piston to TDC when I am doing a leak down test?
I was thinking once the spark plugs are out put a screw driver through spark hole, then crank over motor until screw driver is farthest out. If you know a better way please explain to me.
2.) What is a good amount of psi to pump into the cylinder?
3.) For a leak down test do I need to have the motor warm?
4.) Are these the correct steps: Make sure piston is at TDC. Pump air into cylinder. Listen for air leakage through oil cap, dipstick, throttle body, exhaust?
Exahust= Exhaust valves
Throttle body= Intake valves
Dipstick= Rings
Oil cap=?
Are these assumptions correct? (Oil cap= rings???)
Also anything else I am missing please let me know, thanks.
-Nick
1.) What is the easiest way of getting each piston to TDC when I am doing a leak down test?
I was thinking once the spark plugs are out put a screw driver through spark hole, then crank over motor until screw driver is farthest out. If you know a better way please explain to me.
2.) What is a good amount of psi to pump into the cylinder?
3.) For a leak down test do I need to have the motor warm?
4.) Are these the correct steps: Make sure piston is at TDC. Pump air into cylinder. Listen for air leakage through oil cap, dipstick, throttle body, exhaust?
Exahust= Exhaust valves
Throttle body= Intake valves
Dipstick= Rings
Oil cap=?
Are these assumptions correct? (Oil cap= rings???)
Also anything else I am missing please let me know, thanks.
-Nick
#4
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not sure about the operating temp stuff
a leak down test just tests the PSI, and if the PSI is constant and doesnt change quickly then there are no leaks..
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1.) What is the easiest way of getting each piston to TDC when I am doing a leak down test?
I was thinking once the spark plugs are out put a screw driver through spark hole, then crank over motor until screw driver is farthest out. If you know a better way please explain to me.
I was thinking once the spark plugs are out put a screw driver through spark hole, then crank over motor until screw driver is farthest out. If you know a better way please explain to me.
You need to make sure that it's at the end of the compression stroke/beginning of the power stroke; just TDC isn't good enough. You'll be close when the dizzy's pointing to the cylinder in question.
4.) Are these the correct steps: Make sure piston is at TDC. Pump air into cylinder. Listen for air leakage through oil cap, dipstick, throttle body, exhaust?
Exahust= Exhaust valves
Throttle body= Intake valves
Dipstick= Rings
Oil cap=?
Are these assumptions correct? (Oil cap= rings???)
Exahust= Exhaust valves
Throttle body= Intake valves
Dipstick= Rings
Oil cap=?
Are these assumptions correct? (Oil cap= rings???)
Some other brainy fella here pointed out that you can open up the radiator and check there too if you suspect your head gasket.
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Yeah, I don't know about the other questions, just experiment. Don't think it needs to be hot, don't think it's sensitive to pressure.
Doubt 100 PSI are enough to turn the engine when the piston's at TDC.
Doubt 100 PSI are enough to turn the engine when the piston's at TDC.
#7
"You'll be close when the dizzy's pointing to the cylinder in question."
^Can you explain this better I am a little confused? And yes when I say "crank", I mean with a hand socket.
^Can you explain this better I am a little confused? And yes when I say "crank", I mean with a hand socket.
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4 cycle engines, the crank turns 2x for every 1x camshaft revolution, so in a complete cycle you hit TDC twice, right? The "right" TDC is at the beginning of the power stroke, which is when the spark plug fires. Therefore the dizzy is an indicator of where you're at.
Pop the cap off the dizzy and see which cylinder the rotor's pointing at. Go to that cylinder and get it to TDC with your wrench & driver, do your leakdown. Turn the crank 1/3 revolution, lather, rinse, repeat. For hi-sheen hair with strength of hold, use LayRite Pomade.
Pop the cap off the dizzy and see which cylinder the rotor's pointing at. Go to that cylinder and get it to TDC with your wrench & driver, do your leakdown. Turn the crank 1/3 revolution, lather, rinse, repeat. For hi-sheen hair with strength of hold, use LayRite Pomade.
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Mr. Chumchal, methinks you need to do a little reading up on Internal Combustion Engines 101. Principles apply to all 4 cycle engines, no matter whether 6 cylinders (the one I described, hence 1/3 turn on crankshaft) or 4 cylinders. Good luck
#11
Ya know if a feller can't figure out how to find TDC with number one cylinder firing, then he ought NOT be dick'n with the engine!!... and go get some ed-ma-cation on the basics of backyard auto mechanic'n, get a buddy to help, find a could auto shop, or get a FSM and do some read'n!! Thank the Lord for this here internet!!!
'course I mighta been lucky, grow'n up with my ol' man be'n an auto mechanic, and a good one at that. Hell, he taught me how to make a gasket out of a Kellog's cereal box and ball 'n penis hammer when I was about 8 years old! I knew what the firing order is of a flat head 6 when I was about 7 years old. By the time I was 6 I could name every car manufacturer by sight. By 12 years old I could drive a stick shift. And that's no bull.
'course I mighta been lucky, grow'n up with my ol' man be'n an auto mechanic, and a good one at that. Hell, he taught me how to make a gasket out of a Kellog's cereal box and ball 'n penis hammer when I was about 8 years old! I knew what the firing order is of a flat head 6 when I was about 7 years old. By the time I was 6 I could name every car manufacturer by sight. By 12 years old I could drive a stick shift. And that's no bull.
#12
a proper leakage tester will have two gauges on it and will hook up to a air compressor, you will need to regulate the air so you zero/max out the other gauge so you can tell how much air is leaking.
once the crank and piston are at tdc the air pressure shouldn't move the piston, but if the piston isn't standing on end or the rod it will sping over quick as . lol at least a 1/4 or 1/2 turn atleast .
once the crank and piston are at tdc the air pressure shouldn't move the piston, but if the piston isn't standing on end or the rod it will sping over quick as . lol at least a 1/4 or 1/2 turn atleast .
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You funny, Gnarly4X
This reminds me of when I was about 17 doing the wheel bearings on the Datsun in my sig, pulled the rotor and couldn't get the outer race out.
Well, I didn't have a hydraulic press, so I took it to a machine shop and gave it to the old guy working there. He said, "my 3 year old grandson could do this!" He grabbed a big socket and the 3 lb sledge, and bam! bam! bam! it was out. I slunk outta there humbled like my mama had just scolded me.
Anyway, what's the best test for a pee-pee tuneup?
Well, I didn't have a hydraulic press, so I took it to a machine shop and gave it to the old guy working there. He said, "my 3 year old grandson could do this!" He grabbed a big socket and the 3 lb sledge, and bam! bam! bam! it was out. I slunk outta there humbled like my mama had just scolded me.
Anyway, what's the best test for a pee-pee tuneup?
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