Confusing Outdrive Pressure / Vacuum Test Results

[shackmaninc]

Hello all, I'm looking for some help regarding some confusing pressure and vacuum results. Today i did a pressure and vacuum test on my 290DP-A volvo outdrive exactly how the manual says to do it. Everything checked out perfectly no drop what so ever in the pressure test at 120kPa and no drop at all in the vacuum test at 54kPa. (BTW i am doing both tests from the drain hole) Then as i am walking back to do something i notice that, like a dummy :facepalm:, i left the fill plug out. And so i am very confused how i can be getting these results with that plug out. I don't have a full understanding of how the oil system in that outdrive is set up but i would assume that it is all connected? So i don't know if everything is how it's supposed to be or if i have to test from both holes or if i have a major clog or something please any help would be great.
Thanks

 

[shackmaninc]

Re: Confusing Outdrive Pressure / Vacuum Test Results

Does anyone have any ideas what it could be or what to check. Do you think i have to take the unit apart? Anybody heard of this happening before?

 

[Don S]

Re: Confusing Outdrive Pressure / Vacuum Test Results

Did you drain all the oil out of the drive first?

 

[shackmaninc]

Re: Confusing Outdrive Pressure / Vacuum Test Results

yes i did.

 

[Don S]

Re: Confusing Outdrive Pressure / Vacuum Test Results

It's an impossibility. There are a couple of passages open to oil, and no way that I am aware of for them both to get plugged up by accident.

 

[shackmaninc]

Re: Confusing Outdrive Pressure / Vacuum Test Results

ok that helps, i will keep thinking about it. It is probably something i just missed or something. So if the fill plug was out the air would flow freely?

 

[Don S]

Re: Confusing Outdrive Pressure / Vacuum Test Results

So if the fill plug was out the air would flow freely?

Yes!

 

[shackmaninc]

Re: Confusing Outdrive Pressure / Vacuum Test Results

Alright I was a nummy and found a block in my pressure testing/vacuum set up. :facepalm: After fixing everything and spending a bit more time to make my testing set up nice and leak proof, the system checks out great for the pressure test but the vacuum was no good. It held up to 20kpa and after that leaked fairly quickly about 2-3 kpa/min. I took smeared oil the best i could, vacuumed and then removed the upper gear housing. I couldn't really see anything concusively. I checked all o-rings and found that the o-ring around the oil passage tube was pretty flat. i replaced that with a comparable o-ring. all other o-rings looked pretty good. I then took the shift mechanism apart and saw that the seal around the excentric piston looking and feeling kinda loose. I then smeared a good amount of grease around all o-rings and reassembled. I got the same results. I am thinking about just not worrying about it, buying new o-rings and seal for the uppers housing, lubing everything up and putting it back together. I;m thinking it will be fine being that everything in the upper housing looked immaculate like the day it was made, and it holds about half the max vacuum. Just change the oil after a few trips out and see if there are any signs of water. What do you all think?

 

[captmello]

Re: Confusing Outdrive Pressure / Vacuum Test Results

I would have replaced all those orings and not reused any of them.

Good luck! Let us know how it turns out.