Ducman82

starting at 100 psi "in cylinder" then shutting off the air it drops like a stone to 10, in about 3 seconds.... thats on only 1 cylinder so far.... maybe my craftsman compressor gauge i bought is not sensitive enough, or cheap. ill do the rest and see what the numbers show.

depami

Can you hear/see/feel where it's going?

Ducman82

that one was in to the crank case. in gear works, but only sorta.... to lock it down... URG.

SeanR

Jake, would it help if you ran gear oil instead? :P

Ducman82

20/50 is not gear oil? he he he

using the other comprssion tester hose with the valve in it and a ballon to find TDC. kinda neat. but sticking the car in grear does not seem to "lock it down" as much as i would have liked. kinda fun hitting the air, and watching/hearing the 1/2 ratchet on the dampener bolt spin and smack things....

docmirror

It would be good if you had a crankshaft locking tool. Take the oil fill cap off and do the test again. If you have leakage past the rings, it should be pretty obvious. Also, block the throttle plate open and take off the air cleaner so you can hear any leaks going that way.

Fabio421

Do you have it in 1st gear? It should be in 5th.

depami

It doesn't have to be at TDC as long as the valves are closed. Try BDC on power stroke, valves are likely closed there and the piston can't go any further down.

SeanR

He's got to do that for each piston if he's trying a leak down. Otherwise he'd toss that crank in many different directions.

depami

I think he's doing one cylinder at at time so what's a little turning of the crank between tests.

SeanR

As long as he's got it at the bottom each time, no worries.

depami

Precisely.

I meant turn it to BDC by hand and THEN apply air. DO NOT turn crank shaft by hand while external air pressure is applied to cylinder. Things could get exciting in a hurry turning past TDC by hand with air compressor connected.

SeanR

Oh I dunno, it's Jake, this could be fun to watch if he'd record it. Can we go back and tell him to do this?

Fabio421

I always pull the coil wire when doing a leakdown test. I've never had the engine spin or try to fire but it's just a good practice.

Ducman82

For you kids playing at home, here are the numbers!
from 100psi to 10psi (in seconds)

#1- 6.8
#2-8.6
#3-13.3 (all that oil?)
#4-7.4
#5-8.1
#6-13.0
#7-7.8
#8-5.3

and here are the plugs!

1-4 (left to right


5-8 (left to right)