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Did i do the cylinder leakdown test right?

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2.1K views 6 replies 5 participants last post by  jmderyke  
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#1 ·
So, i just got done doing a kindof preview cylinder leakdown test(it got dark so i just tested the main suspect cylinder, #4 because I found oil on the inside of the plug accompanied by smoke out the tailpipe), but im not %100 sure i did it correctly because ive never seen one done and only had the internet as my coach...

Here's what i did:
Engine cold(all the plugs were already out and i just wanted to try out the tester)
All plugs out
TDC on #4
Compressor at 100psi
Tester at 15psi

Here's what i saw/heard:
%10 immediate leakdown
More like %20 after a small amount of time(plus the compressor kicked back on so i dont know how accurate the reading was)
I heard air leaking through the oil filler tube(no noise at exhaust and no bubbles in coolant)
20180513_210717-1.jpg
(Blah blah harbor freight tools, didnt wanna spend $150+ for something im hopefully not going to have to use a lot)

If time permits, i aim to do a complete test tomorrow. So if someone could spell out for me exactly how to do this test and/or tell me what im doing wrong or what im not doing at all, thatd be great!
 
#5 ·
Did you set the tester up per the manual? I have that same tester, did you adjust the regulator so the needle was in the yellow set area before the test?

Are you sure #4 was at tdc on the compression stroke? Its also a possibility the piston was pushed down with the air pressure and the engine rotated.
 
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#6 ·
1lowcab said:
Did you set the tester up per the manual? I have that same tester, did you adjust the regulator so the needle was in the yellow set area before the test?

Are you sure #4 was at tdc on the compression stroke? Its also a possibility the piston was pushed down with the air pressure and the engine rotated.
Click to expand...
I do believe i set the tester up properly. I am not sure about the compression stroke, just know it was at tdc, im pretty new to this stuff and i still dont really understand that part, i was by myself and couldnt do the "feeling for air" thing... Ill have to visually check that the engine didnt turn, but i doubt it. That's why i only gave it 15psi, one of the few things i picked up from the youtoobs.
 
#7 ·
Have a friend slowly rotate the engine, hold your finger over the spark plug hole. When you feel compression trying to push your finger, you're on the compression stroke. Then use a light and look into the cylinder or use something (like a screwdriver) to feel when the piston is at the very most top part and either have someone hold it there or lock it there somehow with the crank bolt.
When you hook up your guage you need to set the needle right on zero then open the valve on the guage. Anything over 10% bad news. But looks like your gauge has it's own scale....
Did you do a compression test first? Way easier and if you have good compression not much need for a leakdown test.
 
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