Really strange issue with DPSM trim system - hoping for help

[reef55]

2004, DPSM outdrive, with the trim pump inside the boat. I just had the engine pulled and replaced, and while the engine was out, replaced the salty / crusty transom assembly with a low hour fresh water one. Replaced the motor on the original trim pump while at it. Filled the reservoir, left the cap off, and tried to cycle it up and down. The outdrive moves maybe a 1/2 inch in either direction. So here are all the troubleshooting steps I have tried... I am about out of ideas, and would love some guidance. I have checked all over, and I have no leaks inside or out. I have a second entire trim pump, which I tried, and it also wouldn't move the outdrive more than 1/2 inch.

1 - Disconnected the pin from the end of the rams (so they didn't have to move the outdrive). Tried running the pump up and down, and they still only move a 1/2 inch.
2 - Disconnected both hoses from the trim pump. With the cap off the reservoir, when I turn on the pump going up, it sprays a fast stream out one port. When I turn the pump on going down, it sprays a fast stream out of the other port. This seems to indicate there is not a problem with the pump.
3 - With the hoses reconnected at the trim pump, if I disconnect both hoses from one trim cylinder, when I turn on the pump going up, I get a fast stream out of BOTH hoses going to that cylinder. When I turn on the pump going down, I get no spray out of either hose, and the pump sounds like it would when it is unable to move fluid.
4 - With the hoses still connected at the trim pump, I disconnected the hoses from both trim cylinders. When I turn on the pump going up, I get a fast stream out one hose from each cylinder. When I turn on the pump going down, I get no spray out of any hose, and the pump sounds like it would when it is unable to move fluid.
5 - At the trim pump, I swapped the two hoses into the other port, and repeated test 4. When I turn on the pump going DOWN, I get a fast stream out one hose from each cylinder. When I turn on the pump going UP, I get no spray out of any hose, and the pump sounds like it would when it is unable to move fluid.
6 - With the hoses disconnected from the trim cylinders, I am able to push both trim cylinders by hand their full range of motion (and of course, the first time doing this for each, fluid sprayed out of them).

I am no expert on these though, and am really stuck on what to try / test next. I would have thought that test 4 should have had fluid come out the other hoses when I ran the pump down. Since fluid comes out the pump in both directions (test 2), shouldn't fluid have come out both ways in test 4?? Any advice is greatly appreciated!

 

[Scott Danforth]

the two lines going to the cylinders back to a Tee fitting sound like they are crossed somewhere.

from the pump, each line goes to a Tee fitting, then there are two lines, going to the two cylinders.

from the pump, the up-circuit goes to the Tee, then the lines go to the blind end of the cylinders. the down-circuit goes to the Tee, then the lines go the the rod end of the cylinders.

the pump is set for 900 psi going down and about 2900 psi going up (because gravity and prop thrust help move the drive down)

with the cylinders disconnected, does the drive move freely?

 

[reef55]

Thanks for the quick reply. The fluid comes out of both down lines on test 5 above when I press the down button. My initial thought was they might be crossed, but when I traced them against pictures and other setups, they seem correct. And with the test having fluid come out of both down lines, if they were crossed, wouldn't the fluid come out one down line and one up line?

 

[reef55]

the two lines going to the cylinders back to a Tee fitting sound like they are crossed somewhere.

from the pump, each line goes to a Tee fitting, then there are two lines, going to the two cylinders.

from the pump, the up-circuit goes to the Tee, then the lines go to the blind end of the cylinders. the down-circuit goes to the Tee, then the lines go the the rod end of the cylinders.

the pump is set for 900 psi going down and about 2900 psi going up (because gravity and prop thrust help move the drive down)

with the cylinders disconnected, does the drive move freely?

Oh, and yes, with the cylinders disconnected, the drive moves freely

 

[Lou C]

I think that the Volvo SX has a manifold for the trim lines in the gimble housing just like the OMC Cobra, it’s tough to get at with the engine in place, maybe when the lines were connected to that they were crossed..

 

[reef55]

I think that the Volvo SX has a manifold for the trim lines in the gimble housing just like the OMC Cobra, it’s tough to get at with the engine in place, maybe when the lines were connected to that they were crossed..

Hi Lou, yes, it has the same manifold in the gimbal housing as the OMC Cobra did. I followed the lines, and they appear to be connected properly. But if the lines were crossed at the manifold, then when I ran the pump in test 4 and test 5, fluid should have come out something like the port UP and the starboard DOWN lines, or vice-versa, correct? I only get fluid coming out of both DOWN lines, but never get fluid coming out of either UP lines.