86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob?

[njrextreme]

I have another post but maybe im not explaining what the problem is very well. My motor raises and lowers fine with the switch. The problem is when im in the water and put it in gear, it pushes the motor down. The motor will stay up forever without a load on it. I could see atf oil on the main hydraulic and was told by a merc. tech that my top seal in the main ram was bad. So I now have the main ram apart and the plunger pulled out. My rubber o rings do not look tore or bad. I will post of pic of what im working with. I also found a parts diagram but im not sure what all has to be replaced and do not want to buy parts I dont need. I really need some advice and help with this problem. Thanks,
Nick R.

Here is a link to the diagram. It has a repair kit, and a guide kit. Do I need both kits?
http://crowleymarineservice.com/PartsLookUp.aspx

 

[Chris1956]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

Your link didn't work. What do you have an '86 inline 6?

if you see oil on the trim rod, the top Oring is bad. The wiper may be bad as well. If the motor settles under load, either the piston seal is bad or the control valve is bad. Since aftermarket Orings are pretty cheap compared the the Merc kit (ouch!) I would try to replace the orings with some from a HW store. Match them as close as possible. It may at least help you isolate issue.

 

[BryaninFL]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

usually if the motor does this or slowly drops over time, it's a seal in the pump valve body.

 

[njrextreme]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

The motor is a 74 mercury 115 inline 6 that I bolted onto my orig. motors leg, that was a 86 Mariner 90 inline 6. So the trim is the 86 external style with two small rams and a large one that is in the pic. I will try the o rings and go from there. If its the control valve, how do I go about fixing that.

Thanks, Nick

 

[njrextreme]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

Can that seal be replaced? Is it a major job?

 

[Chris1956]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

The top seal can ususally just be pulled out of the cap. The piston unbolts from the rod? Inspect the cylinder for scratches.

Is the manual release valve tight?

 

[njrextreme]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

The top seal can ususally just be pulled out of the cap. The piston unbolts from the rod? Inspect the cylinder for scratches.

Is the manual release valve tight?

Yes, the release valve is tight. The piston unscrews from the rod corect? It looks like it does. I just have never worked on one of these and didnt want to try if it didnt. Thanks again for the help.

 

[BryaninFL]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

The motor is a 74 mercury 115 inline 6 that I bolted onto my orig. motors leg, that was a 86 Mariner 90 inline 6. So the trim is the 86 external style with two small rams and a large one that is in the pic. I will try the o rings and go from there. If its the control valve, how do I go about fixing that.

Thanks, Nick

You would have to remove the t&t motor to get to the pump porsion.

 

[njrextreme]

Re: 86 merc/mariner trim hydraulic not holding motor up under a load. Not a pump prob

You would have to remove the t&t motor to get to the pump porsion.

Thanks, ill post again if it comes down to that.