Trim drifts down by it self.

[jopes]

How does one tell if it is in the pump or the rams? The book only said to disconnect the rams and see if they go up at the same speed, if one was faster it was the slower ram. But nothing how to check out the pump.

How does one check the pump?

Can the pump be repaired at home?

Boat info is in my sig line.

 

[achris]

Re: Trim drifts down by it self.

Sorry, crystal ball in for a 5,000 guess service. You'll have to do just like the book says, disconnect and verify yourself....

Which pump? Presolite (series I, II or II) or Oildyne (metal reservoir or plastic)??? Some can be repair, some can't...

 

[Don S]

Re: Trim drifts down by it self.

How does one tell if it is in the pump or the rams? The book only said to disconnect the rams and see if they go up at the same speed, if one was faster it was the slower ram.

What "Book" are you looking at? The chances of the rams extending or retracting at exactly the same time and speed when disconnected is ZERO.

 

[tpenfield]

Re: Trim drifts down by it self.

I have the same issue with my port side outdrive. It lowers itself over the course of a couple of days.

I got me a flare nut coupler (aka a union) to tie the hydraulic lines together. If the outdrive stays up with the hydraulic lines connected together, then it is probably the pump.

As to whether the pump can be repaired, well that's another story.

 

[jopes]

Re: Trim drifts down by it self.

What "Book" are you looking at? The chances of the rams extending or retracting at exactly the same time and speed when disconnected is ZERO.

Clmer Mercruiser stern drive shop manual. 86-94, ect.

Trim cyclinder quick test.

 

[achris]

Re: Trim drifts down by it self.

Clmer Mercruiser stern drive shop manual. 86-94, ect...

:facepalm: Someone needs to be accountable for calling that load ****e a service manual!!!

Download and save these....

ENGINE MANUAL
DRIVE MANUAL

Chris.....

 

[RRitt]

Re: Trim drifts down by it self.

Generic answer:
drift down is almost always pump regardless of system manufacturer or application. Water in fluid is almost always top of cylinder or leaky motor/reservoir gasket. Seals in ram are usually 3/16", 4mm, or larger in diameter. Seals in pumps are usually around 3/32". Both seals are subjected to the same contaminants, detergents, and PSI. In general, for every failure of a large piston seal there will be 9 failures of smaller check valve seals (in pump).

raise the engine, block it, disconnect plumbing, plug up rams, and remove blocks. If engine stays up then it isn't the rams.

 

[achris]

Re: Trim drifts down by it self.

...raise the engine, block it, disconnect plumbing, plug up rams, and remove blocks. If engine stays up then it isn't the rams.

Errrr, Don't you mean the drive???? The engine's the bit on the inside of the boat!!!

 

[RRitt]

Re: Trim drifts down by it self.

Errrr, Don't you mean the drive???? The engine's the bit on the inside of the boat!!!

you are right. drive or prop would have been a more generic term. either way, raise the hydraulic system such that gravity is working to put pressure on the piston. It will drift down if the ram seals are going bad. Hang a big weight on the prop, tie a length of string that just touches ground, and go have a beer. When you come back any drift down will be obvious.

 

[Don S]

Re: Trim drifts down by it self.

you are right. drive or prop would have been a more generic term.

Not prop either, the trim cylinders don't move just the prop, they move the outdrive, sterndrive, or just drive. Not Prop or engine.

 

[RRitt]

Re: Trim drifts down by it self.

You guys seem bent upon ignoring "generic". I'm trying to frame it so that it could be either inboard, outboard, mud motor, or other. to check whether drift down is from actuator or pump you separate the two parts and plug up the actuator ports. Apply mechanical pressure to actuator and see if it moves. If it does, then it has a fluid leak. If not, then not. same method regardless of whether it is an outboard engine or a farm tractor.

 

[Don S]

Re: Trim drifts down by it self.

You guys seem bent upon ignoring "generic". I'm trying to frame it so that it could be either inboard, outboard, mud motor, or other.

We are in the Mercruiser IO forum. Not the "other" forum.

 

[RRitt]

Re: Trim drifts down by it self.

We are in the Mercruiser IO forum. Not the "other" forum.

that's the idea Don. People should not be scared into thinking that Mercruiser defies the laws of physics and logic. If they have experience with the hydraulics on their snow plow then they should know that most of their experience transfers to marine trim.

 

[Don S]

Re: Trim drifts down by it self.

that's the idea Don. People should not be scared into thinking that Mercruiser defies the laws of physics and logic. If they have experience with the hydraulics on their snow plow then they should know that most of their experience transfers to marine trim.

:facepalm: :facepalm: :facepalm: Prop--Drive--Engine....... All the same thing right ?????

That is what I'm talking about, not hydraulics.

 

[jopes]

Re: Trim drifts down by it self.

Generic answer:
drift down is almost always pump regardless of system manufacturer or application. Water in fluid is almost always top of cylinder or leaky motor/reservoir gasket. Seals in ram are usually 3/16", 4mm, or larger in diameter. Seals in pumps are usually around 3/32". Both seals are subjected to the same contaminants, detergents, and PSI. In general, for every failure of a large piston seal there will be 9 failures of smaller check valve seals (in pump).

raise the engine, block it, disconnect plumbing, plug up rams, and remove blocks. If engine stays up then it isn't the rams.

So in saying that, are the pumps rebuildable? Is there a kit for them?

 

[jopes]

Re: Trim drifts down by it self.

:facepalm: Someone needs to be accountable for calling that load ****e a service manual!!!

Download and save these....

ENGINE MANUAL
DRIVE MANUAL

Chris.....

Downloaded and Saved. Thanks for those.


Now what are the fitting sizes on the pump so I can do the tests on the unit with a pressure guage?

 

[RRitt]

Re: Trim drifts down by it self.

So in saying that, are the pumps rebuildable? Is there a kit for them?

If you can get the correct parts and clear instructions then (i think) pumps are easy to rebuild. Without a kit and instructions then it is probably not a good project. You could end up spending hours trying to find the parts. Choose rebuild kit over seal kit if both are listed. "Seal kits" do not always include springs, ball bearings, poppets, and filters that you might need.

 

[jopes]

Re: Trim drifts down by it self.

Ya. Getting the correct rebuilt kit may be the issue.