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How milky can oil get if ujoint bellows pops loose?

T

twinharbor

New member
Just winterizing here and found some pretty milky oil. I have a volvo penta 280 DP. My exhaust bellows came off a few weeks before hauling, and I have reason to suspect that the u-joint bellows had also come loose when I raised the drive up. The hose clamp was gone when I hauled this week, and the boot was slightly off on the bottom. My question is this: is it reasonable to think that the oil would be come quite milky from a few weeks (let's say 5-10 hours runtime total) if the ujoint bellows was leaking a little?

Next thing I'm going to try is pressure test but I'm curious mainly about the bellows factor.

Thanks!
 
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twinharbor said:
Just winterizing here and found some pretty milky oil. I have a volvo penta 280 DP. My exhaust bellows came off a few weeks before hauling, and I have reason to suspect that the u-joint bellows had also come loose when I raised the drive up. The hose clamp was gone when I hauled this week, and the boot was slightly off on the bottom. My question is this: is it reasonable to think that the oil would be come quite milky from a few weeks (let's say 5-10 hours runtime total) if the ujoint bellows was leaking a little?

A small amount of water (when churned up by the gears) can quickly turn oil milky.

The good news is..... if the oil remains hydrogenated, it normally won't cause any immediate damage.
None-the-less, get it out of there ASAP.

Next thing I'm going to try is pressure test but I'm curious mainly about the bellows factor.

FYI... when you perform a Pressure/Vacuum leak down test, the gear oil must be drained for the Pressure Leak-Down test.
The Vacuum Leak-Down test doesn't care.
A Leak-Down test involves a time frame!
In other words, while the drive is pressurized, monitor how long it will hold XX psi.
Do the same with the Vacuum leak down test.
It is necessary to spin the drive shaft, eccentric piston and the prop shaft while doing the tests.


As for the drive shaft bellows coming loose;

......water enters this area and will reach the main drive gear seal.
......water rusts/corrodes the carbon steel seal surface washer.
......the rust becomes abrasive and starts destroying the seal lip.
......as the drive warms up from use, the gear oil expands some creating a mild positive pressure inside.
......this can cause a small loss of gear oil.
......as the drive cools down, negative pressure builds inside.
......the negative pressure can cause water to be pulled into the interior.


Thanks!
Click to expand...



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You are welcome!

I'll add that during your Pressure/Vacuum leak-down test, you will find that it will leak down a certain amount.
The key is to find at which value it will hold, and that it maintains that value for a duration.
In other words, during the pressure test, if you were to apply 14 psi, and if it was to leak down to 10 or 8 psi, yet it holds 10 or 8 psi for hours, you are likely OK.

As for the vacuum test, if you were to apply let's say 4 to 6 in/hg, it may leak off a bit, but it should reach a point at which it maintains that value.



NOTE: the main drive gear seal is intended to hold gear oil IN, and may not fair quite as well against negative pressure.
Since this seal is within the "dry" bellows area, it satisfies the requirement.


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Don't discount the possibility of a leaky prop shaft or shift rocker arm seal... or even a defective seal on the dipstick.
 
sandkicker - that's what I'm worried about. I already changed the shifter seal a few years ago, and last year I noticed a thin dip-stick o-ring, so got that straightened out. This year though, the oil was far whiter than those past years when those other issues popped up. I'm concerned about those other seals as they appear to move out of the DIY realm and into expensive repair-shop territory. If pressure test holds, maybe I can assume it was the bellows and just change oil and launch again next year.

Thanks to all for replies!
 
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twinharbor said:
sandkicker - that's what I'm worried about. I already changed the shifter seal a few years ago,
FYI..... the eccentric piston seal is directional.
If not installed correctly, a portion of the steel housing will be exposed to the water! If in salt water, it will quickly begin to deteriorate.

and last year I noticed a thin dip-stick o-ring, so got that straightened out.
The dip stick and drain plug O-rings are identical, and must be replaced each time removed.

This year though, the oil was far whiter than those past years when those other issues popped up.
I'm concerned about those other seals as they appear to move out of the DIY realm and into expensive repair-shop territory.
There is nothing about re-sealing an AQ series that is out of the experienced DIY realm.

If pressure test holds, maybe I can assume it was the bellows and just change oil and launch again next year.
I would not assume anything..... I would suggest doing a full and complete leak-down test.
Click to expand...
 
I have a 280 DP... is that AQ series? I was under the impression shaft seals and beyond required a lot of specialty tools. Guess some more homework is in order!
 
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twinharbor said:
I have a 280 DP... is that AQ series?
Yes, any Volvo Penta drive that is of main suspension fork/pivot tube geometry would be an AQ series.

I was under the impression shaft seals and beyond required a lot of specialty tools. Guess some more homework is in order!
The only specialty tool would be a prop shaft bearing carrier puller, of which Volvo Penta does not offer.
For this, you would need to build one of my puller tools.

Prop shaft carrier puller tool 4.jpg

Prop shaft carrier puller tool 5 .jpg

The rest is fairly simple if you are reasonably mechanically inclined.
Click to expand...
 
Given the design of the AQ series, sealing of the drive is accomplished by a seal at the point that the drive shaft enters the drive housing, not by the bellows, although running long enough with a leaking bellows will result, as noted above, in failure of this seal.

Drain drive of all oil before running a pressure and a vacuum/leakdown test.
 
Thanks again Rick. I still need to read up (and didn't pressure test yet, just finished shrink wrap) but looks like the seal kits vary in how many they include.

Gearcase kit (this appears to show the ones you included in your pic)
https://www.amazon.com/dp/B004AR1EA4/ref=nav_timeline_asin?_encoding=UTF8&psc=1

Or there's the big kahuna package:
https://bpi.ebasicpower.com/shop/vo...nd-lower-volvo-aq-duo-prop-280dp-290dp-875741

I'm guessing the complete kit is better because I can change them all out. Open to your thoughts and recommendations.

And I found my shop manual, I can read through that as well :)

Thanks!
 
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twinharbor said:
Gearcase kit (this appears to show the ones you included in your pic)
https://www.amazon.com/dp/B004AR1EA4/ref=nav_timeline_asin?_encoding=UTF8&psc=1

There is no eccentric piston seal nor looped gasket in the above kit.

Or there's the big kahuna package:
https://bpi.ebasicpower.com/shop/vo...nd-lower-volvo-aq-duo-prop-280dp-290dp-875741

The above kit includes prop shaft seals for the Duo Prop.

I'm guessing the complete kit is better because I can change them all out. Open to your thoughts and recommendations.
There are parts in the second kit that you will not need for a re-seal.
You may be better off purchasing what you need individually.


And I found my shop manual, I can read through that as well :)
Be sure to have an OEM manual. Use the Seloc or Clymers as a supplemental only.

There will be procedures in the OEM manual that will appear to be more difficult than actual.

And..... they will NOT show the use of a prop shaft bearing carrier puller tool like mine.
I would suggest NOT using a slide hammer.
Click to expand...
 
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