koolaid_kid

iTrader: (21)

Well, I did a search and paged through several of the 293 pages, but none mentioned leak down testing. So:
I am going to do a leak down test on my car. I will be ordering a quality kit, but I have a couple of questions on the procedure. I found some articles on the web, and they differ in the following:
Some recommend removing the rocker arms, some do not. Is this required?
Some recommend locking the engine, most do not. Is this required? If so, how would I do it on my automatic car?
Some claim that this test can pinpoint the leak to the valves, rings, cylinder walls. How is this done, the writeups do not say.

Thanks in advance.

bczee

iTrader: (12)

Neither is required, I didn't remove any rockers or use a lock on the fly wheel... but it might make it easier if you did use one of those recommendation.
What I did was to use a socket and breaker bar to hold the balancer (by rotating it till TDC). It was a bit hard in that the compressed air tried to push the piston back down. For that reason, those to recommendations (rocker and flywheel lock) would make it easier to keep the engine piston at TDC.

To lock the flywheel. there are tools designed to handle that. For your Auto Trans, remove the inspectin plan to get access, there is also a tool to take the place of the starter (I think), and another one that is inserted into one of those plastic covers (to the flywheel).

Once you have the leak down test going. You will read the percentage of leakage from the gauge. (I had 5% or less on each cylinder) By listening to where you hear the air escaping from will pinpoint the leak (rings, valves, etc..)

hope this help understand the process.

1BADAIR

iTrader: (1)

When at TDC the engine won't really want to turn over. if your off alittle it will.
pull the dipstick out a little and have it as quiet as possible in the area. then listen at the throttle body, dipstick and exhuast. The exhaust will be the hardest to hear.
If the rings are bad the you will hear the air from the dipstick, intake valve the TB, exhaust valve-exhaust. If you have a head gasket issue you may see bubbles in the radiator

koolaid_kid

iTrader: (21)

Thanks for the replies. I understand now. Just hope I can nail TDC for each cylinder.

Country Boy

iTrader: (24)

If you take the rockers off, why do you need TDC? TDC is just so the rockers are closed, right?

2000TransAmWS6

iTrader: (12)

you need it at TDC so that the compressed air won't force the piston down, and also so that you can get an accurate reading... with the rockers off it just really wouldn't matter if you were at TDC on the compression or exhaust stroke (so you could do companion cylinders at the same time).

Country Boy

iTrader: (24)

I didnt have a problem with it forcing the piston down, but I was a six speed and the wheels were on the ground.