Outdrive pressure test help

[tony dz]

I have a 78 Mercruiser 165. Changed the outdrive lube to discover it was milky although it did not appear to be low. Still got a little more the an quart out of it. Anyhow, trying to pressure test the outdrive just to be sure. I don't have a manual so I've been piecing together a procedure from what I can find online. Here's what I've done so far..

1) drained the out drive and left it on the boat
2) hooked up the pressure tester to the bottom drain hole and filled to 5psi for 10min - no pressure change
3) increased to 10psi for 10 minutes - no change
4) increased to 13 psi for 3hrs. the first 2.5hrs had no change at the end I saw a 1/2 psi drop, but only after I handled the guage/pump, so I'm suspicious if it leaked from the gague/pump itself.
5) increased to 14 psi for 10 minutes - no change

So now I'm seeking advice.. does this sound like an ok procedure? Did it pass? If it passed, why did I have milky oil?

Thanks for the help!

 

[tony dz]

Re: Outdrive pressure test help

It's been holding 14PSI for over 1.5hrs now. Any thoughts?

 

[ziggy]

Re: Outdrive pressure test help

sounds like the seals are holdin to me......


how are the bellows?

 

[Gary H NC]

Re: Outdrive pressure test help

Between the draining and the pressure test did you put new washers on the drain plugs? The correct way is to pressurize and turn the driveshaft in gear at 45 degree increments.wait a few minutes in between turns.If that passes then a vacuum test is needed,same procedure turning the shafts.This is best done with the drive off the boat. I test mine overnight. If it holds 15psi overnite and passes vacuum test it should be fine.But water did get in so there is a problem.

 

[tony dz]

Re: Outdrive pressure test help

Thanks! Gary, couple rookie questions. Is the driveshaft what links the outdrive to the motor or where you mount the prop(or both)? Is it possible to turn these while still mounted? I did shift into gear and rotate the prop, I felt a clicking, but it didn't feel like it was engaged.

 

[tony dz]

Re: Outdrive pressure test help

Oops, No I didn't replace the o-rings.. Is it possible/likely they just weren't tight enough?

 

[Gary H NC]

Re: Outdrive pressure test help

The hard plastic drain plug washers need replaced every couple times the plugs are removed.They leak easy. The prop shaft is on the prop,the drive shaft you need to pull the drive to see.You can just put it in gear,turn the prop until it engages,then turn the motor by hand.Don't start the engine with no lube in the drive. If you find it is leaking on the guage put some dish soap and water in a spray bottle and start checking around drainplugs,propshaft with the prop removed.If you find nothing there then pull the drive and inspect the seals around the shaft behind the ujoints..

 

[Gary H NC]

Re: Outdrive pressure test help

Thanks! Gary, couple rookie questions. Is the driveshaft what links the outdrive to the motor or where you mount the prop(or both)? Is it possible to turn these while still mounted? I did shift into gear and rotate the prop, I felt a clicking, but it didn't feel like it was engaged.

The clicking means it was not in gear..

 

[tony dz]

Re: Outdrive pressure test help

Gary,

Took your advice and pulled the drive off the boat... first time, easier than I expected, hope it goes back on that easy... anyhow did the 45degree and waited at 15psi.. seems to be holding still but may have dipped 1/2 psi... hard to tell on the gauge.. I'll let it sit overnight and check in the morn..

Other observations:
- When I pulled the drive about 1cup of water drained. Is this OK? I was guessing it was from the raw water lines.
- The approx 5" rubber gasket that goes around the drive shaft is a bit chewed up. Not falling apart, but definately needs to be replaced.
- Inside the bell housing (think that what it's called) the grease is green/blue in the middle and brown/sludge on the outside. (see pic)

Here are some pics. I'm not really sure what I'm looking for here, but maybe somebody with a trained eye can see something suspious.

 

[tony dz]

Re: Outdrive pressure test help

I checked the pressure this morning and it's still holding at 15PSI. I guess it passed the pressure test. I'll try to do a vacuum test tonight. What vacuum level do I test at?

Also, anybody notice anything suspect on the pics in my previous post?

 

[Gary H NC]

Re: Outdrive pressure test help

The u-joint bellows must be replaced.There should be no water in there period.You may have caught the problem in time.The water will seep in around the drive shaft seal when the bellows is bad.If i remember right i vacuum mine down to about 12hg or something like that. Make sure you clean all that brown grease out and pump the ujoints full of clean grease.Clean the gimbal bearing up and reach in and make sure it feels smooth while turning. Grease it good and put the new bellows on.
Hopefully you caught it in time..

 

[Gary H NC]

Re: Outdrive pressure test help

Also there should be an online service manual for that. Some of the guys here have links to it.
Post a new thread with year and drive info that you need a manual.
Sorry i don't have the link.You will need it for bellows replacement and putting the drive back on..

 

[tony dz]

Re: Outdrive pressure test help

Thanks for the help Gary! Couple more questions so I know what to look for next time.

- How could you tell it was the ujoint bellows as opposed to another seal or exhaust belows? Was the brown sludge a sign?
- The water did appear to come from the water hose area like it possibly came out of the water hose. Should this area be dry too?
- Lastly if my outdrive passes the vacuum test now does that mean the drive is still good and the bellows was probably my only problem?

 

[tony dz]

Re: Outdrive pressure test help

Hey Gary, any feedback on my last post? I appreciate the help.