Mercruiser trim cylinders will not retract? *UPDATE*

[johnsland8]

I have a Mercruiser 165 in a 1988 Bluewater. I'm not sure of the drive year, it's not the original drive.

I rebuilt the trim cylinders, installed them, and bled the system. The pump will run in both directions and there is plenty of fluid/oil in the reservoir.

The cylinders will extend just fine but they will not retract. If I relieve the pressure by disconnecting the forward return hose on one side, they will retract just fine. It acts as if the fluid is not being allowed to return to the reservoir. In the manual it appears the return line is a straight shot from the cylinders back into the reservoir.

I was just curious if anyone could provide the most likely cause of the problem?

 

[Bondo]

Re: Mercruiser trim cylinders will not retract?

Re: Mercruiser trim cylinders will not retract?

I was just curious if anyone could provide the most likely cause of the problem?

Ayuh,...

Most likely, you misplaced the Lines....
Have you Greased the outdrive's Pivot Points,..??..??

 

[Don S]

Re: Mercruiser trim cylinders will not retract?

Re: Mercruiser trim cylinders will not retract?

If lines were crosses, it wouldn't go up either.
Sounds more like defective valves in the trim pump. Any signs of water in the trim pump?
Here is a link to the OEM manual.
http://www-alt.mercurymarine.com/mnetdata/SERVICE/CRUISER/Servmanl/6/6covr3.pdf
Section 1C will help you troubleshoot it step,by, step.

 

[johnsland8]

Re: Mercruiser trim cylinders will not retract?

Re: Mercruiser trim cylinders will not retract?

Thanks for the replies...

Thank you for the link to the service manual, I will be going through that today.

Just for the record, the lines are definitely not crossed or misplaced, that has been checked and double checked.

The drive moves up and down freely when not connected to the cylinders.

There is no water in the system, the oil is clean and fresh.

One quick question though... I know the down side of the system is the low pressure side. I have been testing the cylinders when they are disconnected from the drive unit so they do not have the weight of the drive to assist them. Could this be an issue? Shouldn't the down side have enough pressure or force to overcome the up side return pressure by itself, provided the system is functioning correctly?

Thanks again...

 

[johnsland8]

Re: Mercruiser trim cylinders will not retract?

Re: Mercruiser trim cylinders will not retract?

edit

 

[johnsland8]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

I discovered the trim system appears to have been plumbed incorrectly by the PO.

According to my manual, the high pressure up side is supposed to travel directly from the pump to the up side of the cylinders. The low pressure down side is supposed to travel from the pump, thru the reverse lock out valve, and then into the cylinders. My system is plumbed with the up side going into the reverse lock out valve and then into the cylinders. The down side then has to force the return fluid to pass thru the reverse valve instead of directly back to the pump.

Could this be causing me problems? Or will it work the same regardless?

 

[johnsland8]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

I discovered the trim system appears to have been plumbed incorrectly by the PO.

According to my manual, the high pressure up side is supposed to travel directly from the pump to the up side of the cylinders. The low pressure down side is supposed to travel from the pump, thru the reverse lock out valve, and then into the cylinders. My system is plumbed with the up side going into the reverse lock out valve and then into the cylinders. The down side then has to force the return fluid to pass thru the reverse valve instead of directly back to the pump.

Could this be causing me problems? Or will it work the same regardless?

Nobody has any thoughts on the plumbing issue?

How do I know for sure if it's actually the high pressure side without a test gauge?

Are the outlets marked? Mine are on the bottom of the pump reservoir so it's impossible to see without removing the whole thing from the boat.

Any other thoughts or ideas before I go fumbling around with it?

Thank You for any help you can provide...

 

[pappacherry]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

I am going thru the same problem. My outdrive will not trim down, but it will go up. I don't think you can actually cross the hoses going into the distribution manifold block. I believe my problem is the 2 trim cylinders. I have 2 trim cylinders in good shape coming in the mail. Are you sure you rebulilt your trim cylinders correctly?

 

[Fishermark]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

I'm surprised you have a separate reverse lock out in a 1988 boat. Here's a diagram showing the lines with a system that has the reverse lock out:

 

[johnsland8]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

Yes, that's how the manual shows it as well. My system is just like that except I do not have the hydraulic sender, it's electric.

The previous owner purchased the hull and the drive unit separately, so it's not the original for that boat.

The two lines coming out of the pump are switched on my boat. So when I press "UP" it sends fluid thru the lockout valve and then extends the cylinders, instead of going directly to the cylinders. Consequently, when I try to retract the cylinder with the "DOWN" button, the return line does not flow directly back into the pump but first travels back thru the lockout valve.

Two questions:
1. Could this affect the cylinders retracting correctly? Or should it still function regardless of the plumbing route?

2. How do I know for sure that when I press "up" the fluid is being sent thru the High Pressure side of the pump? If someone crossed or changed the wires to the solenoid it could actually be actuating the low pressure side correct? It looks right but how can I know for sure? Are there any markings on the pump?

Thanks again.

 

[johnsland8]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

Are you sure you rebulilt your trim cylinders correctly?

Yes, I am pretty sure. I have tested them both off the boat with fluid and they appear to be functioning just as they should. They both extend and retract smoothly and fluid is expelled from the proper return port during both actions. It acts like something is simply not allowing the fluid to exit the cylinders when I try to retract them with trim system.

 

[Bondo]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

1. Could this affect the cylinders retracting correctly?

Ayuh,.... Sure Could,.... I believe I mentioned that Along tme ago...

How do I know for sure that when I press "up" the fluid is being sent thru the High Pressure side of the pump?

Donno which pump you've got,... There've been several....

 

[johnsland8]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

Donno which pump you've got,... There've been several....[/QUOTE]

I believe it's a Prestolite pump. It has a metal reservoir.
It has only one solenoid.

It looks just like this:

 

[milmor88]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

i'm having the same problem with mine exactly when i connect power to the green wire...it makes the trim go up...when i connect the blue, the engine wines very quickly and doens't sound liek it's moving any fluid...i'm taking my pump apart tommarrow....does anybody have a diagram to put all the spring and balls back in the right spots?

 

[cr2k]

Re: Mercruiser trim cylinders will not retract? *UPDATE*

GREEN = Grass > Down trim.
BLUE = SKY > Up Trim.

If you are getting up on green you are plumbed wrong.