leak down test

[smithers584]

can someone give me a link or tell me how to do one, cuz i am dumb and have never seen one done. thanks, s13 sr by the way.

[slider2828]

It is a tool that does a leak down test. Do a search on google.... You will find it there.

[NIK90s13]

chech this out.


hey everyone, im sure i am not the only person who has done this, but i just made my own tool for checking vacumm lines for leaks and it worked flawlessly. cost was around ten bucks, everything purchased at lowes. just hook it up instead of your intake and pressurize your system with about 20psi from an air compressor. this will pressurize your IC piping if you are turbo, and if you open the throttle body it pressurizes the lines and mani, just dont use to much pressure because valves and shit are still open. hope it helps some of you chasing vacumm leaks.

Parts needed:

PVC adapter with one threaded end
PVC threaded insert of the same size to seal the one end
1 schrader valve, like off a tire
rubber coupling
sealent

i dont know much about uploading pics, but try this
go here http://s79.photobucket.com/albums/j1...rrent=tool.jpg
hope the link works

[smithers584]

i know i made that thread! This is something completely different though. It somehow pressurizes the cylinders and stuff and measures how fast everything is leaking out or something like that. the thread i made was simply for checking IC piping and vacumm lines.

[NIK90s13]

The only thing like that I know of, Snapon sells a valvespring remover that can be used with the head on. There is a hose that pressurizes the chamber (with the cams off)so the valves do'nt drop with the keepers and springs off.

[slider2828]

That is true, basically it is like a compression test, but for your coolant system. Basically it is a cap thing that hooks onto your radiator in place of your radiator cap. Then you pressurize the system and up to some PSI(I forget). Then basically you let it sit for X amount of time and see how much PSI you are leaking and where it is leaking. You can tell where it is leaking by using a mechanics stethescope(SP?) and you can tell what is wrong with your car. Either coolant system, cylinders, and things like that....

[NIK90s13]

That will test the head gasket, plus the compressin test is about all I know to do. What are you after ''Smithers''? I'm not understanding what your trying to do. Forgive the ignorance, I'm on medication!! LOL

[smithers584]

i am not sure what i am after, some reassuring confidence i guess! i just am not sure what the test is for, thats what i want to find out. just bored and want to test everything i can since i just got my car running again and have checked almost everything else.

[aznpoopy]

try the first link on google, you lazy monkeys! ;)

http://www.geocities.com/dsmgrrrl/FAQs/leakdown.htm

for dsms, but you get the point.

a leakdown test is like a compression test, except it lets you diagnose what is bad a little more accurately then a basic comp test.

bring the cylinder to TDC so the valves are closed, and then pressurize the cylinder using an air compressor. leave it on and check for noise in the following locations.

whooshing at exhaust = bad exhaust valves.
whoosing around the intake = bad intake valves.
wooshing from your oil cap = bad piston rings.
bubbles in your coolant = bad headgasket
air going into an adjacent cylinder = bad headgasket

this is usually done AFTER you have done a compression teset and have found bad comp on a cylinder.

edit: clarification on TDC... its TDC for whichever cylinder you are testing, not just tdc for cylinder #1. should be obvious, but you never know who will read this in the future...

[NIK90s13]

got it!! I'v been there!! I just put in My ka24de , we put in the 91 exaust cam on the intake side.
I was unsure of it. Run your compression test and the leak down. you should be fine. It'll run great and all will be great in the world!!!!!

[NIK90s13]

If you pressurize the sylindar at T.D.C. it will spin the crank and open the valves, right?

[aznpoopy]

i think you might be using too much pressure if you are cranking over the engine. you want the valves to stay closed so you can hear where the air is leaking out from.

[NIK90s13]

Got ya, Low air pressure shouldnt spin the motor.

[smithers584]

you got me aznpoopy, i was a little lazy on this one. haha!

[ledzeppelin240]

I would do a leak down test before a compression test because it is way more accurate, can be done on an engine out of the vehicle, does not matter what camshaft you have. Try doing a compression test with a aggressive cam...

It is best to do a leak down test with a warm engine so everything is sealed, piston at TDC on compression stroke, pinch the PCV valve off because a piston ring leak may enter the PCV valve causing a intake air leak. You can also check for cylinder taper, and may determine if the cylinder has a carbon build up.

[MELLO*SOS]

If during a leak down test, you hear air coming from the exhaust ports, what exactly does that indicate? Does it mean worn springs? Time for a valve job? Carbon stopping the valve from closing 100%? Something else?

I have two cylinders with similar symptoms, they both leak a good deal of the air out of the exhaust port. One says "40%" leak and the other a "65%" leak on this tester:

http://i1.ebayimg.com/01/i/07/5c/6f/7e_1.JPG

test conditions & procedure... Tested motor on engine stand ("cold"), using 100psi, each cylinder was set to TDC & pressurized. Buddy held crank in place with ratchet on crank pulley nut. Heard leaking from exhaust port, inspected cam lobes (not opening valves) & rocked crank slightly to ensure piston was at TDC. Went back and tested cylinders twice to make sure.

Just curious what the results mean?

[aznpoopy]

the only thing that can tell is that there is a problem with your exhaust valves. it's up to you to dig into the head and figure out what the specific problem is.