Just rebuilt the trim cylinders, now the outdrive won't stay up under load

[KetchiMan]

Volvo 300 with a DPSM outdrive.

Had a leaky trim cylinder so I bought a new seal kit and I believe I followed this Youtube video (

) exactly with the same seal kit he uses in the video.

The trim system was working perfectly BEFORE the rebuild, but it was leaking fluid, the fluid in the reservoir was milky, and the reservour ended up being full of really nasty sludge.

The rebuild included all of the seals, and seemed to go without a hitch. It sat on the trailer in the shop for a couple of weeks after the rebuild and didn't leak a single drop of fluid.

Took it out last week and the motor won't stay trimmed up under load. She creeps back down to it's lowest position due to the force after a few seconds. The pump will actually push the outdrive up while under load, but the prop force pushes it back down within a few seconds. Doesn't seem to be leaking any fluid, but I didn't investigate that very thoroughly yet.

Seems obvious that something went wrong with the seal kit rebuild, but I'm not familiar enough with how the system works to know which seals to check or if it might be something in the pump, or elsewhere.

Thanks!

 

[HiWard]

My guess: Could be the piston seals in the cylinders or the return valve in the pump, probably the former since everything worked prior to the rebuild. That is assuming you have no leaks externally. There's a guy called Michael Romer on youtube who has some videos on how to test for leaky internal piston seals.

 

[Scott Danforth]

My guess is you sheared off a piston seal when re-installing the rod and piston

 

[Bondo]

Ayuh,...... If yer confident the cylinder seals were installed properly, if could be the check-valve in the pump,.....

 

[Scott Danforth]

easy enough to check. raise outdrive all the way, then pull the rod end lines. if oil comes out the cylinders, the piston seals are bypassing.

 

[Lou C]

There is a trick to installing those to protect the seals, in the instructions for the kit I used on my Cobra it showed how to use an alu can to make a guard to protect the seals….I’ll see if I can find a pic

 

[Lou C]

Delete wrong pic

 

[Lou C]

Tin can with green tape on it
I’ll see if I can photo those instructions to make it more clear

 

[Lou C]

 

[Lou C]

Look at the tin can at the end of the cylinder

 

[Lou C]

Ok watched the vid out of curiosity, the kit used has a different seal than what was used on the OEM and is different than the BRP kit I used on the Cobra (OEM), there is one big red seal taking the place of 1 oring and 2 plastic spacers. Not sure if that makes a difference here or not. But, you might be able to re-do the job using the BRP kit....
The other difference when I did it was that I did not remove the cyls from the transom mount, one of the hydraulic fittings did not want to move, (36 year old boat used in salt water) so I left it be and used the internals from a spare set of Cobra rams I bought (the old rods were pitted) and just rebuilt it on the boat. As long as the cylinder is in good shape, (no scoring or pitting inside) no need to take the cylinder off.
After bleeding it worked perfect, still on the original trim pump.

 

[KetchiMan]

easy enough to check. raise outdrive all the way, then pull the rod end lines. if oil comes out the cylinders, the piston seals are bypassing.

Hey Scott,
That sounds like a good plan, but what do you mean by "rod end lines". Is that the upper of the 2 lines going into the cylinder? Or is that both lines on both sides?

 

[KetchiMan]

Ayuh,...... If yer confident the cylinder seals were installed properly, if could be the check-valve in the pump,.....

Had that same thought... then one of the smart guys here (in Ketchikan... I think you were here, weren't you Bondo?) said that if it was just one of the cylider seals, the cylinder on the other side would still be able hold the outdrive trimmed up under power.
Does that seem accurate???

 

[Lou C]

https://www.marineengine.com/newparts/part_details.php?pnum=OMC0985060

this is the kit I used, it is for all the Cobra trim cylinders, in the early years of the Volvo SX they used the same exact trim cyl and then they changed the body of the cyl so that the rear fitting doesn't have the trim line running on the outside of the cylinder but is built into the cylinder, and also they changed the loop end that connects to the drive via the rod, but not sure if the internals are the same, or not.
I don't think Volvo themselves ever offered a kit because they would much rather sell you a new cylinder for a grand lol. Same nonsense with the power steering actuators that they say can't be rebuilt but can be depending on what's wrong with them.

 

[Bondo]

Had that same thought... then one of the smart guys here (in Ketchikan... I think you were here, weren't you Bondo?) said that if it was just one of the cylider seals, the cylinder on the other side would still be able hold the outdrive trimmed up under power.
Does that seem accurate???

Nope, never been there, but my best friend, 'n mentor used to live there, Don S, who unfortunately passed away some years ago,...

I donno whether one cylinder would hold it up, under power,....
Test it like Scott said, on the trailer, run it up, then remove one of the down lines, 'n see if it holds,....
You'll loose the bit of oil in the line, but it should hold/ stay up,....

 

[KetchiMan]

Nope, never been there, but my best friend, 'n mentor used to live there, Don S, who unfortunately passed away some years ago,...

I donno whether one cylinder would hold it up, under power,....
Test it like Scott said, on the trailer, run it up, then remove one of the down lines, 'n see if it holds,....
You'll loose the bit of oil in the line, but it should hold/ stay up,....

That's right... It was Don S! Always used the "Ayuh...". Good dude.

Do you happen to know which are the down lines? My guess is that it's the upper one and that the lower on goes into the front of the cylinder... but I want to be sure.

 

[Lou C]

Replaces OEM 0778202.
0985060 - Cobra Tilt & Trim Seal Kit for one cylinder. There are internal variations in the cylinders so the kit includes parts for all possible options. Please see the Tech Info Download on this page for instructions.
Trim /Tilt Cylinder Seal Kit - Stern Drive
1987-1996 all Cobra® / King Cobra®
This kit services all OMC Cobra models.
Evinrude Johnson OMC 0985060 - Tilt & Trim Seal Kit Cobra is equivalent to parts:

• 3854247 Volvo Penta
• 985060 Evinrude Johnson OMC BRP
• 778202 Evinrude Johnson OMC BRP

UPC: 745419018580

this is a cut n past from the description of the kit I used, notice it is also listed for Volvo Penta....

 

[Scott Danforth]

There are two ports on the cylinders. The rod end, and the blind end

Raise the drive, pull the rod end hose (down hose) and press up. If oil comes out the cylinder port, your seal or seals are bypassing

I have a background in hydraulics and I still cut the seal when I did mine. It happens

 

[KetchiMan]

There are two ports on the cylinders. The rod end, and the blind end

Raise the drive, pull the rod end hose (down hose) and press up. If oil comes out the cylinder port, your seal or seals are bypassing

I have a background in hydraulics and I still cut the seal when I did mine. It happens

This sounds pretty smart... How can I tell which is the "rod end" or "down hose".

THanks

 

[Horigan]

Actuators have two ends, rod end where the chrome piston rod comes out aft end of the actuator, and the head end (or blind end) on the front side.