new oil tank check valve - slight leak OK?

[motuman]

I ordered a new check valve, for the remote oil tank pressure feed, and per Don's advice in this thread

https://www.bbcboards.net/showthread.php?t=1238211

did a quick back flow test by blowing into the valve.

There is a very slight leak, and I can hear a whistling sound, which goes away if plug the inlet side with my finger.

Question - Is a very slight leak normal or expected? Or should this seal 100% when blowing into the outlet side?

[bass.man65]

Normal it needs to bleed off after shutdown.

[JOE54]

^^^^^^^ +1

[EuropeanAM]

+2

[motuman]

Thanks guys!