70 lt1 leak down results

[Dennis D.]

Leak down with a cheap tester on a cold engine
. Posted compression test last week and consistant with 1 at 180. Most at 190, and a couple at 195. This seems consistant as well, although crazy high leakage. All hissing coming from oil filler.Opinions?
20191009_154408.jpg20191009_142902.jpg20191009_154507.jpg20191009_154257.jpg20191009_154323.jpg20191009_154343.jpg20191009_143439.jpg20191009_144417.jpg
Compression results
20191006_142731.jpg

[Rich G.]

[Dennis D.]

Re: 70 lt1 leak down results

Thanks Rich. If I'm understanding you, I put 90# in , then zero out the percent gauge before connecting to cylinder.

[Rich G.]

[Dennis D.]

Re: 70 lt1 leak down results

Dennis

on my gauge we set 80# on the input side and with the output side blocked with the the shut off in the off position the other gauge should read 80#. That would be 100%. Then connect to the cylinder while your friend holds the propeller at TDC for that cylinder. Then turn the valve on and the second gauge reads what’s being held. Numbers in the mid 70’s are good. 64 is minimum. Sometimes we touch up the input to keep it at 80#. Also we have the advantage of being able “rock” the prop a bit to get exactly TDC which is difficult in a car.

matbe that’s a different unit which I’m not familiar with, so let’s wait and see what somebody more experienced says.

Rich

So someone suggested I modify the tester I have and get rid of the % gauge. I moved the pressure gauge to the vacated spot and plugged the first port. I now have a gauge I can pressure with 100#, then plug into a cylinder and read the pressure difference. I think this is the setup you were explaining.

I retested cylinder 5,(since that was where the balancer was last set. The new setup showed 9% on the same cold engine instead of the 50% I had before. Ill probably retest the rest, but Im feeling good they will be similar.
Here's a pic of the original #5....

[Dennis D.]

Re: 70 lt1 leak down results

New results with modified gauge set at 100# inlet. Compression is great. These numbers seem quite good as well. Up until now I haven't really disturbed anything. Wondering if I should remove valve covers to check seal. Not sure I can check guides with just removing valve covers. Also wondering if I should adjust the valves since I still have the balancer taped in 90 degree increments. All part of the while i'm at it senario.

[Patrick B.]

[Rich G.]

Re: 70 lt1 leak down results

Dennis

Thats more like it!

Rich.

[Bob I.]

[Dennis D.]

Re: 70 lt1 leak down results

Thanks Patrick. I don't know when the valves were done. But judging from other things I've found, I'm not that confident the previous owner did it correctly. Will just be another item off my list.

Rich. I thought you'd relate to my second testing. Makes more sense.

[Dennis D.]

Re: 70 lt1 leak down results

Hey Bob How are you. All the air is coming from the valve covers. Very faint. Not leaking anywhere else. Assuming its normal air passing the rings, being the compression and leakdown are looking good.

[Richard G.]

Re: 70 lt1 leak down results

How did you hold the motor at TDC?
That has always been the issue when I preform this test.

[Dennis D.]

Re: 70 lt1 leak down results

How did you hold the motor at TDC?
That has always been the issue when I preform this test.

I got lucky with taping the balancer. I did it in 4 segments and each cylinder seemed dead on tdc. That's why I'm thinking to leave it on and check the valves.

[Bob I.]

Re: 70 lt1 leak down results

How did you hold the motor at TDC?
That has always been the issue when I preform this test.

Sometimes the piston will moved during the test. Were wondering if you experienced that during your testing. If you do, leaving the other plugs in helps.

[Richard G.]

Re: 70 lt1 leak down results

Next time I will do both, index the balancer and do one plug at a time.
In my experience if I was off only a skosh the air pressure would rotate the motor.
Thanks for the tips. I really enjoy this site.
Rick