Motor is a b18c block, 9 to 1 pistons, fully built b16 head.
I bought a shitty Leak Down tester from Harbor Freight.

Using the leak down gauge it comes with, numbers were all over the place. It's near impossible to ZERO that gauge out.
I replaced the leak down gauge with a standard gauge and measured the percentages myself.

Leak down: Around 8-9% loss in 1, 2, and 3. 4 had about 10%.

Did a warm compression test.
Compression: 170 in 1 and 2, 165 in 3, and 162 in 4.

I can hear a little bit of air from each piston if you take the oil filler cap off.
Is that normal, or wtf??
No way all 4 pistons rings are bad?

No noise in intake, no bubbles in coolant.

I am confused. Compression is great.

Any thoughts? What should I do next?

 

Those numbers are not bad. Generally 5-8% is normal loss on a used motor, 10% or less isnt bad. You dont have to do anything else you passed the test. Congrats you got a B.

Compression is not horrible if you have Low compression pistons... That looks like 8.5:1 tho. But you are showing close compression from cylinder to cylinder so not as much to worry. Now if you have CTR pistons then you have something too worry about lol

 

I was mostly just worried about the air noise coming from the oil filler cap. Shouldn't it be silent if the rings and everything is good?

 

No youre probably just hearing the air escaping past the rings... Its normal. If it was coming out of youre intake or exhaust manifold then you may have a valve seat issue. With the numbers that low i doubt that is the issue...its just normal blowby

 

Man, that makes me feel 100 times better. I am about to start boosting this motor. I am pulling it to put it in another car, and wanted to make sure it is healthy.

I did dyno 184whp with it last month n/a. Would have made more, but I ran out of fuel on stock injectors and pump.

 

Those numbers are nice

 

Healthy motor. You will always have some leakage on a leak down 2-10% is pretty common and as stated 170-160psi on a low compression motor is good. Boost the thing and have fun.

 

Appreciate the feedback.