DPS pressure and vac testing

[Toddavid]

Drained the oil on my 2014 DPS-B drive at end of last season and was bummed to see oil the color of Bailey’s. Approx 400hrs on it.

With oil drained, I hooked up my pressure tester, and it held 15psi for 10 minutes. I didn’t have a vac tester, so I plan to do that test this month.

Soapy water would reveal a pressure leak, but how do you find a vac leak?

 

[muc]

Use motor oil at the possible leak points. It will either get sucked in or you will stop loosing vacuum.
Have you pulled the drive to check for water in the bellows? The seal behind the u-joints will sometimes allow water in but still hold pressure.
Also, when you’re pressure testing did you twist twist, push pull and wiggle wiggle the shafts and shifter like the manual instructs?

 

[Toddavid]

Boat is in my marina high and dry, plan on doing a full re-check this weekend.

There is a chance I may have gotten water in my bellows through the bilge, as I had a weeping water pump that I wasn’t aware of and a blocked bilge pump discharge port (lake inspector put rubber plug in that port instead of the galley sink, I didn’t catch it until water was almost up over the bilge pump). But I thought VP had an input seal that holds both pressure and vac, unlike a Merc, so water in the bellows shouldn’t cause drive intrusion?

Guess I’ll see this weekend…

 

[BRICH1260]

Boat is in my marina high and dry, plan on doing a full re-check this weekend.

There is a chance I may have gotten water in my bellows through the bilge, as I had a weeping water pump that I wasn’t aware of and a blocked bilge pump discharge port (lake inspector put rubber plug in that port instead of the galley sink, I didn’t catch it until water was almost up over the bilge pump). But I thought VP had an input seal that holds both pressure and vac, unlike a Merc, so water in the bellows shouldn’t cause drive intrusion?

Guess I’ll see this weekend…

I wouldn`t think that you would have gotten water into the bellows from the bilge unless the water got up the the drive shaft in depth, that`s pretty deep and would have ruined your starter motor for sure.

 

[muc]

I wouldn`t think that you would have gotten water into the bellows from the bilge unless the water got up the the drive shaft in depth, that`s pretty deep and would have ruined your starter motor for sure.

agree with this.
single lip seal by the u-joints, just like mercruiser.

 

[DRCrowe]

I had water in my lower this year too. I tried a pressure test and and it held pressure with no drop overnight. When I switched the pump to vacuum, it started dropping pretty fast. The shift seal on mine went bad. I tore mine down for inspection which was good. If you do any tear down make sure to replace any o-rings that you pull apart as they are single use. Good luck!

 

[Toddavid]

I had water in my lower this year too. I tried a pressure test and and it held pressure with no drop overnight. When I switched the pump to vacuum, it started dropping pretty fast. The shift seal on mine went bad. I tore mine down for inspection which was good. If you do any tear down make sure to replace any o-rings that you pull apart as they are single use. Good luck!

Thanks for that note.

Here’s a related question for the group: boat is in the marina warehouse (Maryland), so I won’t be able to run it and get the outdrive oil warmed up. Any issue removing the drain plug and pushing out the oil with a few psi of pressure applied to the upper fill hole? It’s been real cold last few days.

 

[BRICH1260]

Thanks for that note.

Here’s a related question for the group: boat is in the marina warehouse (Maryland), so I won’t be able to run it and get the outdrive oil warmed up. Any issue removing the drain plug and pushing out the oil with a few psi of pressure applied to the upper fill hole? It’s been real cold last few days.

I do not see that hurting but I dont think it would be necessary. The oil will drain, might take a little longer being cold. You can remove one of the upper plugs to aleve the vacuum inside to make it flow quicker.

 

[Toddavid]

Well, did the vac and pressure test again today, and couldn’t find any issue.
Drained oil fully, pressurized to 5 psi, twisted prop shaft back and forth, shifted gears forward back, pushed in on the gear selected, and pressure held for 10 minutes.

Did the same at 10 psi, and then at 5 and 8 in of vac. No drops.

Sigh.

The fresh oil I drained had water contamination, too, so I assume even after I find a leak, it will take several oil changes to make sure? Boat has been on covered rack since the last change.

How hard is it to preemptively replace the prop shaft seals with drive on the boat? Duo prop shaft.

 

[Grub54891]

The water this time might have been leftovers from the
last time. Cold weather may affect the tests, stiff rubber on the seals

 

[Toddavid]

The water this time might have been leftovers from the
last time. Cold weather may affect the tests, stiff rubber on the seals

Yes, I assume it is water left over. What’s the best way to fully flush it out?

 

[Grub54891]

Put some oil in from the top, trim the drive up down and leave sit with the drive level. Remove the lower plug and let it sit. Others say to put in mineral spirits and flush after with oil. Never tried that myself. I’d imagine sea foam would do the trick also.

 

[muc]

Have you pulled the drive to check for water in the bellows?
Have you used the Volvo special tool to check for a bent prop shaft?
Are your props out of balance?

 

[Toddavid]

Pulling the drive this week.

No evidence of a bent shaft. For the record, there hasn’t been loss of oil, just water ingestion. Always proper level on dipstick, and no oil sheen ever sheen on water.

Props were refinished a couple season ago, small ding on outer edge of one blade. No impacts since.

 

[DRCrowe]

If you find water in your bellows you will have most likely found your culprit. I don't believe the output shaft has a water seal, only an oil seal. I've read others question the oil plug, filler and drain o-rings. Lots of places to fail but easy to address with a couple of bucks on OEM o rings and seals. I worked in a boat yard years ago and became a believer in Volvo Penta. When they fail it is commonly chinese parts or lack of proper maintenance. The other good news is all the amazing help from guys on this forum (a lot smarter then me) who are happy to help!

 

[Toddavid]

Drive was pulled, no water found in bellows.

I then pulled the top cap off the drive to make repeated filling and draining with new oil easier, to flush out the water.

That‘s when I noticed a few small trails of corrosion that made their way past the top cap seal, which is a double lipped o-ring. Not sure how that happened.

I cleaned up the corrosion trails, smeared a thin layer of RTV on the surface where the seal sits, installed a new seal, and did a sea trial yesterday, about an hour of running around.

New aluminum anodes installed for good measure, too.

Pulled the props and drained off a few ounces of drive lube this morning and all was golden and clean. Will check periodically through the season.

 

[Toddavid]

20hrs later and I’m still battling this issue. It takes three or four outings for the issue to present itself as cloudy drive oil (I pull the props and start to drain).

Still no oil leaking out, just a bit of water being sucked in from somewhere.

Each time I see milky oil, I change it. That’s getting expensive with VP oil running almost $30qt.

Besides replacing all seals on the drive, any other suggestions?

Only 420hrs on the drive, fresh water only.