gen II drive fails pressure test, no leaks found

Shift shaft seal ?

You did that .

Did ya spray , where your pressure tester is screwed into lower unit?

Did you spray pressure tester?

yes, yes, yes

Look for lower case crack at lower torpedo housing in front, where lower unit could have hit something

na, i soaked the hole thing down, found nothing, and no damage evident

What PSI?
Have you done a vacuum test? Maybe that will reveal the issue.

14psi, i even tried 5 psi . i didnt do a vacuum test because how am i going to find a vacuum leak if i can't find a pressure leak

Although merc has no pressure spec, OMC had one of 17-18 psi. I typically use 15 psi for normal checking. And it is only to hold pressure for 2-3 minutes not all day. If a leak is not seen in the first minute or two it is usually good to go. The pressure should stabilize after about 30 seconds and stay at set point for 2-3 minutes. I am sure it can stay for longer but I dont remember ever waiting that long. A leak is a leak and it would show itself quickly. With the exception of the shift shaft seal and seal under water pump, ALL other seals are under a rotating load so as long as the seal surface is clean and no deep groves all should be good.

An outdrive typically produces ~ 7-10 psi under normal conditions.

I would say increase pressure and move things while under pressure. shift shaft, prop shaft, vertical shaft in lower if cases are separated, u-joint assembly while in gear etc.

Vacuum may not show a pressure leak per say but may find a weak seal none the less. If I remember it should hold ~ 6-8 in/hg.

I would also recommend the next time you see the snap on truck they sell a kit of rubber stoppers of various sizes/shapes. One works perfectly to plug the oil passage in the lower/upper so you DONT have to use your thumb.

Agreed. Go boating!

Jeff

ok, ok ok, i am not too big a man to admit when im wrong, after reading and replying to my post yesterday, i went back to the pressure tester and sprayed it up more, i was sprayingthe hose and gauge area but then i sprayed under the bottom of the pump and within seconds, got a bubble.
i pumped up the pressure to 15psi and pinched the line with visegrips, went back 2 hrs later and released the VG and sure as ****, the pressure had held. i did the same thing overnight and it was still over 12psi. i filled the drive with lube, and installed it on the boat and called it a day
so, bottom line is, keep looking, you'll find it

any system like these over time air will escape and there is nothing you can do about it. permeation through the seal and orings is normal. Even on high vacuum industrial machines where we would pull vacuum down to 10 to the minus 6 (.000001) torr for semiconductor process equipment and check for leaks with helium leak checkers there almost always was some very small leaks with butyl rubber and silicone orings and seals.

I would suggest to only check pressure for a couple of minutes. Every leak I have seen is visible in a short time,