OMC Cobra pressure test fail

[gohawks688]

First my drive specs/info: 1987 OMC Cobra with an OMC 3.0. Purchased boat as a project, it has not been in the water for 8 plus years. approximately 150 hours
So when I removed my drive I drained the oil..... it was fairly milky. Crap. This lead me down the path of a pressure test. I built the rig to attach to the lower oil drain hole. My drive failed the pressure test. I have a factory manual which states "pressurize to 16-18 psi, drive should not lose more than 1 PSI in the first three minutes." Well it does, it loses about 5 in the first three minutes. It is down under 10 PSI withing 7-8 minutes. Crap. Out comes the soapy water in a spray bottle. I can;t find any leaks anywhere. Areas I paid special attention too:
prop shaft- removed prop tipped drive up on end. sprayed soapy water into carrier bearing area. no bubbles. spun prop, no bubbles.
Drain plugs: replaced the top one (had to buy impact driver) no leaks. No leaks around tester fitting. No leaks at dipstick
Top gear housing plate/gasket, no leaks. Removed cleaned and reapplied gasket sealer, no leaks/no change
Water pump housing: no leaks. I did just change it recently. I did read somewhere that running on muffs if you have too much water pressure on your hose can cause a blow buy into your case. Tested this theory with no oil in drive. no water introduced. Can there be a leak in the water pump/adapter plate i'm not seeing?
Ujoint seal: sprayed water all around Ujoint seal. No leaks noted.
tester itself: submerged the tester itself to prove that was not the case of the leak. Pass

So I split the case and pressure tested the lower unit seperately, and it passed with flying colors. Held pressure for hours. No leaks. So i thought it was just the Orings between the upper and lower case. I replaced those and put the drive back together. Same results, failed pressure test.

So my questions for those OMC wizards out there.
How closely do we follow the " do not lose more than 1 PSI in the first 3 minutes" I'm assuming there is some wiggle room. though I think I am outside that range.

How much luck have you had with the soapy water leak detection method? Am i just missing the leak?

If the lower unit tested fine and I have replaced the orings between the upper and lower that points me at the upper. I see nothing from the outside of the case. Are there any common leaks on the upper gear case. where should i look?

Thanks for the help!

 

[Scott Danforth]

did you pull the whole drive to replace the bellows? if you did and found water in the bellows, your input shaft is gone. if the bellows leak the input shaft gets rusty and that chews up the seals

 

[gohawks688]

I did pull the whole drive, to replace my shift cable. The bellows looks great no water inside. My ujoint/shaft have no rust on them. I sprayed soapy water on the input shaft seal and saw no leaks.

The only thing I can think of is my impeller shaft seal. I think I am going to pull the water pump housing and see i can track down the leak underneath it. Hopefully I don't have to pull the adapter plate.

 

[gohawks688]

Well I pulled my water pump housing, impeller was toast. Crap. I did find the leak though! I have a leak around the impeller shaft So i am going to thread the adapter plate holes and push it out. Not sure how to replace the seal once I get there though. any one know how to do this?

As for the shredded impeller I am kind of at a loss. I just installed it, and never run the engine dry. I guess i could have spun the vanes the wrong direction when installing it? Time to flush all the cooling channels in the drive and flush the heat exchanger.

 

[Pedrocasas]

No Title

do you have pictures of how it looks bro? the milky oil and the area where its leaking from???