Coolant pressure test -- acceptable bleed off?

[mattbta]

Is there such a thing?

Trying to determine if I have a problem with my second set of refurb heads. Got a pressure tester and put it on after sitting overnight in the garage. Left it on @ 15 psi for 24 hours and it was down ~3/4 pound. After 48 hours, it was almost 2 pounds down, but weather got cooler so maybe some change attributed to temperature.

Is this indicative of a problem? All I can really find on my GM SI is that a couple pounds rather quickly is bad. Should it hold 15 indefinitely? There are no external leaks now.

Just trying to get a feel before I tear into it....again. The only reason I got the tester again is because my oil pressure slowly dropped to 20 at hot idle. I drained the oil which was fresh after the second set of heads went on and had ~500 miles on it and the filter had some milkshake in it. I'm just hoping that's residual from before when it was leaking. I have planned to due really short OCI's to get anything left behind out of the system.

Thanks,
-Matt
2004 L59

 

[Scottydoggs]

cold air could be a factor for sure, as well as the bleeder/pump set up having a small leak.

id run it to temp res cap off and top it of as it takes coolant, and run it. keep a daily eye on the coolant level when its ice cold every time as well as the oil for a few days. if that checks out id think your good to go.

i say to check it cold because the tanks level will change as it gets hot and back to cold. why they have a hot and cold line on the tank.