Skunk.Werks

iTrader: (2)

So i just ran a leak down test on a junk yard d16z6 that I picked up for a swap and I was concerned by the amount of sludge in the cylinder head so I decided to leakdown test it before I wasted time putting it in my car.

I use an OTC brand gauge that cost around $80 and isn't the type you find at Harbor frieight. Instead of a gauge that reads in green/yellow/red its simply two psi gauges and you calculate the difference by a chart in the instructions. Here are my results with observations about pressure escaping and from where.

Each cylinder is pressurized to 90psi on the left gauge and the right gauge should read 89psi for 1% leakdown 88psi for 2% leakdown and so on.

Cylinder #1 @ 90psi = 33psi (air escaping intake)
Cylinder #2 @ 90psi = 16psi (air escaping exhaust)
Cylinder #3 @ 90psi = 38psi (air escaping int. @ exh.)
Cylinder #4 @ 90psi = 13psi (air escaping exhaust)

I performed each cylinder twice for consistency and made sure that each cyl was done on the compression stroke at TDC with valves closed. Both times numbers were within the same general results.

Something tells me i'm doing something wrong if I get these kind of numbers because that would mean I have over 70% leakage on each cylinder. And why does the numbers alternate between every other cylinder. This motor is sitting on the floor of my shop and test was done at room temp of about 60* degrees. I peaked into the exhaust ports and all the valve stems look white. I pulled the plugs and they seemed normal color.

Tomorrow i'm going to do the same tests on my daily driver with known low compression in 3 cylinders to see if my results mimic the junkyard motor to confirm or deny that I am doing the test right.

Any help would be appreciated.

Skunk.Werks

iTrader: (2)

This is my gauge, it has good reviews on the web by people who have used it so it cant be junk.

fcm

Before doing anything else, adjust the valve lash on the junk yard motor, to elliminate tight valves as the problem, it sounds like valves are not closing completely.

It may also be burnt valve seats. 94