Compression leak into oil pan?

[Nosroxs]

Alright guys this is a new one on me but here we go.. I just bought a 6bolt 4g63t engine for 500$ and getting ready to do the 7bolt to 6bolt swap but anyways i pulled the oil pan off to check the bearings, and when i had the pan off i slowly rotated the crank while all plugs were in and i hear compression hissing down in the crank area closest to the oil pump like cylinder 4 but not sure exactly were its coming from.. Is this normal?

 

[3kgt2nv]

since the engine is cold the rings will leak some. before you go thru the work i would do a leak down test to check how healthy the motor is

 

[Nosroxs]

since the engine is cold the rings will leak some. before you go thru the work i would do a leak down test to check how healthy the motor is

Would it be normal to hear that hiss out only in one spot? There is no exhaust manifold or injectors installed. It does have the intake manifold bolted on but no throttle body. No timing belt either that is why i turned it slowly so if i did come into contact with a valve i wouldn't hurt it, but anyways it felt like it had decent compression, i know i wouldn't get full compression because of a couple valves being open and no injectors being in but the compression i did have sounding like it was hissing down into the oil pan real close to the oil pick up tube or that side of the engine but no where else..

 

[curt-s]

It will leak slightly where it can. Minute differences between oil saturation on the rings/cylinder walls, ring rotation positions.. all that has an effect on where a slight amount of air will escape. You will have to do a full compression or leakdown test to ensure if your numbers are falling where they need to on a per-cylinder basis. That entails different levels of assembly being required.

Can you see any damage to the cylinder wall in #4 from below?

(btw you couldn't really "feel" like it had decent compression because 150 in 1,2,3 and 120 in 4 would be difficult to tell physically )

 

[northernawd]

cylinder leakdown test at tdc, try spraying some oil in there to seal up the rings a bit.