Volvo Penta Trim Cylinder issue

N

Nievo

Cadet
Joined
Jul 9, 2025
Messages
8
Tried to take the boat out yesterday for the first time and realized I could not get it to trim all the way up or down. Checked the fluid and it was low so I added some and did the 5x up and down to bleed it. Unit would still not go all the way down, was acting like it was hung up on something. Decided to check and see if it was the unit or the cylinders/pump. Unhooked one side and a time and ran it through a cycle. Left side went all the way up and down no problem. Right side will not go all the way down, gets to within the last couple inches and the cylinder acts like it is plugged/jammed.

Both the cylinder and pump are stupid expensive units. Any way to tell for sure if the pump for that cylinder is bad or if there is something wrong with the cylinder? Any other things I might be missing that it could be?
 
N

Nievo

Cadet
Joined
Jul 9, 2025
Messages
8
Just disconnected both cylinders. Left one is firm and doesn't have much play when I try and push it in or out. Right one has about 2-3 inches of "quishy" play in it. Right one does not want to move in or out when I run the trim.
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,774
Pull the cylinder cap and look to see if there is any damage

A rebuild kit for the cylinders is reasonably cheap
 
N

Nievo

Cadet
Joined
Jul 9, 2025
Messages
8
Just disconnected the hoses from the right cylinder and no fluid came out, even when I run the trim. Disconnected the hoses from the left side and was blasted with fluid.
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,774
I don't know what you are talking about. I don't watch videos. Not much to a hydraulic cylinder. The gland is threaded in and needs a pin spanner
 
N

Nievo

Cadet
Joined
Jul 9, 2025
Messages
8
Scott Danforth said:
I don't know what you are talking about. I don't watch videos. Not much to a hydraulic cylinder. The gland is threaded in and needs a pin spanner
Click to expand...
I think maybe we are thinking of different cylinders. These are on a Penta SX-A and don't seem to have a normal cap to pull.

I did remove both cylinder and run the trim. Fluid squirts out of the left side no problem when I run up or down but nothing comes out of the right side. Am I correct in thinking that each side has a different pump that runs that side and the pump is bad?
 
N

Nievo

Cadet
Joined
Jul 9, 2025
Messages
8
Mine is the sx-a, not the sx. Not sure if that would make a difference with the pump or not but the rebuild kit is different.

Why would fluid come out one side and not the other with the cylinder disconnected though if it's not the pump?

EDIT: I just looked them up and the SX-A and SX do have completely different pumps.
 
Horigan

Horigan

Senior Chief Petty Officer
Joined
Jun 12, 2016
Messages
697
Yep. Blow air into the left cylinder lines and it should come out the right cylinder lines.
 
N

Nievo

Cadet
Joined
Jul 9, 2025
Messages
8
I will try clearing the lines. Just weird that it would be both lines on that side. I couldn't get fluid to come out of either one going up or down.
 
ESGWheel

ESGWheel

Senior Chief Petty Officer
Joined
Aug 29, 2015
Messages
727
Nievo said:
I will try clearing the lines. Just weird that it would be both lines on that side. I couldn't get fluid to come out of either one going up or down.
Click to expand...
I am going to suggest you have a failed right side cylinder and it spewed debris (like a chewed-up O-ring) and that in turn has clogged the lines. Another alternative is that the hyd lines themselves are the issue > by delaminating its possible they collapsed internally. I think this is less likely as 2 internally collapsed lines at same time is not likely. That said I am bothered by hyd pressure not spitting out that debris when they were disconnected, and you ran the trim pump up and down.

My suggestions:
  • Tackle the trim cylinder first, ie do a rebuild on it. Suggest making sure you know what kit is needed and its lead time and take apart the cylinder first > you may find it is not rebuildable.
  • For the lines, get new ones. If they are clogged so badly as to resist clearing under the hyp pump pressure they probably have internal damage and while you may get them clear, they may burst on you later.
Also, when getting the new lines make sure you get some extra O-rings > those little suckers are easy to lose or damage. And do not overtighten the fittings. Its something like only 7 to 9 foot pounds if I recall correctly. That is not much at all and if you are not familiar with how much force that is, suggest this: get an inch-pound wrench like this (link). Set up an arrangement where you tighten a 7/16 head bolt to 96 in-lbs (which is 8 ft-lbs). Now take that 7/16 flare nut wrench you will use on the fittings and tighten that bolt just a little more. Do this a few times and you will get the feel of what it takes. Its not much!

Good luck and keep posting question / updates.
 
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,206
The people trying to help are getting confused, You have a different system then they are familiar with. Your trim pump is outside the boat on the transom shield.

Your pump only has up and down outlets. It doesn't care or even know about the port or starboard rams. Fluid comes from the same manifold.

Yes you push the cylinder end cap down and dig out the round wire circle clip then pull the ram out.

You have a symptom I've not seen before, no idea what the cause is. My guess is that one of the o-rings behind the pump cover has failed and is allowing the fluid to bypass.

Your going to have to start disassembling things looking for the problem.

Years ago I had to replace many cover kits and complete pumps. I'm one of the techs the figured out that you could just unplug the wires to the electric motor instead of replacing that harness in the boat. Wow did Volvo get mad about that! Later pump kits came with the wires soldered to the motor so you had to replace the harness.

You should determine what version your boat has. There were many, maybe talk to a good Volvo parts person. The latest cover kit is real good and we don't see many problems anymore.

I'll attach the instructions that come with the kit. Note that this is pretty old, there maybe newer versions.
 

Attachments

  • 47702429 trim pump install.pdf
    705.7 KB · Views: 2
M

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
2,206
I missed that you are already looking at the cost between the kit and complete pump. At $300 I would recommend the complete pump.
 
ESGWheel

ESGWheel

Senior Chief Petty Officer
Joined
Aug 29, 2015
Messages
727
muc said:
Years ago I had to replace many cover kits and complete pumps. I'm one of the techs the figured out that you could just unplug the wires to the electric motor instead of replacing that harness in the boat. Wow did Volvo get mad about that! Later pump kits came with the wires soldered to the motor so you had to replace the harness.
Click to expand...

I had a similar experience when I worked at a British Leyland / Fiat dealership back in the 70s. The TR7’s with their pop-up headlights were notorious for failing to pop up (or down). Warranty was short lived back then and these cars would come in by the dozens over the year with failed pop-ups. We would change out the motor with attached circuit board for $$$. We were required to turn in the busted units and a lot of the replacement units we used were reconditioned. Being curious, we figured out it was a diode that was blown, a 5-cent part at Radio Shack when they did that sort of thing. We demonstrated this cheap fix to the dealer’s Mgt and boy did they get pissed and said “Do not do that!”
 
You must log in or register to reply here.
Top