VP DP-SM failing vacuum test

[KevinBN7]

I have been lurking here for a while and cant seem to find info on my questions. I have replaced the seals on the lower gear cases of both drives. Both drive pass the presure tests with no issues and only one of the drives passes the vacuum test. Now that one drive loses vaccum I need to diagnose here it is leaking. The manual states to pour "heavy oil" on the seal to see if if it still looses vaccum. I am using a mity-vac pump attached to an adapter I made. I am using the dip stik hole. Since one drive passes the test I feel confident in the equpiment.

now for the questions.
What oil should I use on the seal? Motor oil, assembly lube or something in between
What order should I test the seals? Does it matter?
since the prop shaft seals are new should I conetrate on the gear shift and yoke?
should I lay the drive so the oil stays around the seal?

The drives are 2000 DP-sm 1.95 4112096574 they are driven by 7.4 GSI Volvo penta.
If we need more info I will be home during the day tomorrow and can get what is needed

Thanks
Kevin

 

[Don S]

Re: VP DP-SM failing vacuum test

The drive takes GL-5 Synthetic gear lube. That is a spec, not a specific manufacturer.

Most drives fail the vacuum test because the input shaft seal is not designed to hold vacuum. If you tip the drive back and fill the area around the seal with very heavy gear lube, you can usually test the rest of the drive.

 

[KevinBN7]

Re: VP DP-SM failing vacuum test

Don Thanks for the reply. I did the additional tests with the drive tipped and the area around the input shaft filled with GL5 mobil 1 synth gear lube. (this is what I planned to fill the drives with) The drive still lost vacumm at the same rate as the pre test. I flipped the drive and did the same for the shift seal. No change the drive still looses vacuum. Proceeded to the prop shaft seals with no change. It only take 5-8 minutes to go from 5 inches of vacuum to zero. I view this as a pretty severe leak.
The fact that it passes the pressure test (10 PSI overnight with no loss) leads me to believe it is still loosing vacuun due to the outer seals. so I question my results.It is reasonable to me that the input seal should not hold a vacuum since it operates in a dry evnivronment (in the bellows) and doesnt need to stop water from coming in. I am a little unclear of how oil around the seal is supposed to stop a leak.

not sure where to go next so any help on the next step is appreciated
Kevin

 

[Don S]

Re: VP DP-SM failing vacuum test

I am a little unclear of how oil around the seal is supposed to stop a leak.

It doesn't stop the leak permanently, it just masks that seal from leaking while you check the other ones.

Make sure your pump and fittings aren't the problem.

 

[KevinBN7]

Re: VP DP-SM failing vacuum test



It looks like I found my leak. I am glad I have two drives to compare so based on Dons advice of checking my tools to be sure they are giving me a false reading. One of the threaded holes for the dip stick was repaired with an insert and was loose and leaking. I think I have attached photos. Thanks
Kevin

 

[Don S]

Re: VP DP-SM failing vacuum test

You need a new top cap, and reshim it when you install it.