Vacuum testing a Volvo DPH outdrive

[frocco]

Hello all, I had a little water in my DPH-D1 drive at the end of the season. I pressure tested the drive and it passed according to the Spec in the DPH Shop
manual. I replaced all the upper and lower o-rings, shift seals as well as prop shaft seals. I pressure tested when finished and it holds 14psi for over 3 hours without losing even 1 psi.
( that´s when I ended the test) The DPH shop manual does not list a vacuum test for this drive but I did one anyways. I used the spec's suggested for the DPS-B drive
The vacuum test fails, I lose about 1 inch Hg per min. Has anyone done vacuum tests on a DPH? the only seal I did not replace was the U-joint seal which I believe is a one direction seal which might fail in a vacuum test anyway.
The 0-ring between the drive half´s was not replaced either. The o-ring I would expect to fail under pressure and vacuum if it was the issue.
Since there was water in the drive oil, I don't believe the issue was with the u-joint seal because there was no water in the u-joint bellows. I could replace it to ease my mind I guess,
but if it truly is a one way seal then it might not pas a vacuum test which would mean the drive might not be designed to pass one!
Any comments or experience Here?? Thanks in advance.

 

[Chris_d]

I don't know for sure but I would expect a vacuum test to fail as some of the seals are designed to work with positive pressure on the inside only, sucking from the inside will lift the seal tips up and make them leak.

I could be wrong and it would be interesting to know if that is the case?

 

[frocco]

That's my dilemma! I think think the shift seal and the u-joint shaft seal are only one way. the prop seals are definitely 2 way.
There are multiple of each. each facing the opposite direction. I reread the dph workshop manual again last night. It says to perform
a pressure and vacuum test but only gives the values and instructions for the pressure test. I think I will order the u-joint shaft seal and
replace it. Cross my fingers that it will fix the vacuum leak, but I don't believe that it was the source for the water in the drive.

 

[Ville_V]

I reconditioned my two DPH-A drives last winter. New bearings, shims and new o-rings and seals. Pressure and vacuum tested the drives after the job and both held for hours without even a small drop or rise in pressure.
For the vacuum I got the following instruction which is for the Penta DPE model outdrive.
Put 14-16 inches of mercury (Hg) vacuum. Rotate the universal joint clockwise while shifting into forward and reverse. The drive must hold vacuum. It must not loose more than 1 inch in 3 minutes.

I have done the same pressure and vacuum tests to few DPH drives after my own drives and all has held.

 

[frocco]

Thank you Villi_V. that is what I thought, I was using the specs from the DPS which sound the same as the DPE.
I ordered the u-joint seal and another drain plug seal, if that doesn't fix it I will move on until I figure it out.

 

[frocco]

Just updating my old post. I replaced the u-joint seal and the drive had no problem holding 15psi pressure as well as 15 in Hg overnight.

 

[papparazzi]

Just updating my old post. I replaced the u-joint seal and the drive had no problem holding 15psi pressure as well as 15 in Hg overnight.

@frocco where did you buy the pressure tester? I believe it requires a special adaptor to screw on the oil infill screw ? Thanks

 

[frocco]

Sorry for the delay, I bought the adaptor from Marine parts source I believe. a standard mercruiser outdrive filler adaptor will thread into
the dph adaptor. part number - 885753 Nipple. it was pricy but required if you are doing any of the drive work yourself.