'77 Merc 850 power trim issue

[JoshOnt]

So I am finding that the power trim must have a leak or something since when I trailer the motor it comes back down fully within 45 min or so. Also when on the water I have to frequently trim up. Any ideas on what might be happening? I have checked all lines and connections and they seem fine no leaks. I have tried triming it up and down a few times (father said it might help) but other than that I don't know where to look.

 

[merc850]

If it's the external pump 2 shocks kind try this:
Put some Loctite blue on the plugs when you reinstall them.

 

[Chris1956]

That issue is usually caused by one/both the piston seal leaking internally or the control valve malfunctioning.

The piston seal is Teflon and requires a special tool to be installed. Rebuild kits for the trim cylinders are probably still avail, but you will want to determine which cylinder is leaking, as either cylinder will affect the trim..

Control valves were replacement only option.

 

[JoshOnt]

That issue is usually caused by one/both the piston seal leaking internally or the control valve malfunctioning.

The piston seal is Teflon and requires a special tool to be installed. Rebuild kits for the trim cylinders are probably still avail, but you will want to determine which cylinder is leaking, as either cylinder will affect the trim..

Control valves were replacement only option.

Would you have any idea on what an aprox cost would be to have it rebuilt professionally?

 

[Chris1956]

Well, the last time I had it done many years ago, the trim cylinder seal kits were $35 and the labor about the same. You might source the kits and see if Merc still makes them. If not, you will need to do it yourself or take to an independent mechanic.