Tlt/Trim hydraulic hose replacement on my '79

[79Merc175]

Early model with 2 cylinders and the hydraulic pump/motor located inside the boat. Anyone know of any tips, tricks, or gotchas to look out for; plus I have a few questions.

1. Seloc recommends 5w-30, is this good enough or should I be using something else?

2. Should the OB be locked in the full - up position when I do the work?

Thanks in advance!

 

[Laddies]

Re: Tlt/Trim hydraulic hose replacement on my '79

5W30 is fine over the years they have used almost any oil I like dexton
It should be filled in the up position

 

[Chris1956]

Re: Tlt/Trim hydraulic hose replacement on my '79

Those PTT units are not self bleeding. There is a several step procedure you will need to follow to bleed them.

 

[79Merc175]

Re: Tlt/Trim hydraulic hose replacement on my '79

Thanks guys. Chris1956- this several step bleeding procedure; can you elaborate on this?

 

[Plainsman]

Re: Tlt/Trim hydraulic hose replacement on my '79

What does "Early model" mean?
My 1976 115 HP is self bleeding T/T. There is a vent screw above the fill screw, I just loosen that and power the T/T up and down. I replaced all 4 hoses this year and it worked great.

 

[Scaaty]

Re: Tlt/Trim hydraulic hose replacement on my '79

OK.. just curious here, as back in (74-76), I was told to use and did with no problem straight Non-Detergent 30w?

 

[Laddies]

Re: Tlt/Trim hydraulic hose replacement on my '79

Scatty, over the years merc has recomended just about anything that comes in a oil can, In the early 70s when at service school they said you should not use ATF, after using it for years, so we ask why and the awnser was it will damage the o-rings in the system by causing them to swell. So when returning to the shop we took a can put some ATF and o-rings for the tilt system, the next fall when the service rep. (also the instructer at Fondulac) showed up we showed him that they hadn't swollen a bit and for 4 or 5 years evertime we saw him we got out the can again, he finally through it in the trash and said "There i won't have to ck those damn things again" and we still use dextron--Bob

 

[Smig]

Re: Tlt/Trim hydraulic hose replacement on my '79

This is an installation manual for the two ram system. It may have something that helps

PTT Manual

This is the page on filling and bleeding.
Filling and Self-Bleeding

 

[Chris1956]

Re: Tlt/Trim hydraulic hose replacement on my '79

Plainsman, The PTT cylinders are not self bleeding. I am not sure how yours were able to bleed themselves, w/o help. If you look on the top the the cylinders, there is a bleed screw. If you look on the cylinder, adjacent to where the two hoses attach, there is another bleed screw. Both of these must face up, when bleeding. So you can bleed the down side of the PTT with the cylinders attached (top bleed screw). But you must remove the cylinders and face the Up bleed screw up, to allow the bubbles of air in the cylinder to escape. The procedure is to face the "Up" bleed screws up, remove one of them and run the pump up, until there are no more bubbles. Replace the screw. Now do the other cylinder, replace the screw and install the cylinders. Now remove a down bleed screw and run the pump until no more bubbles. Replace the screw. Now bleed the other cylinder.

 

[79Merc175]

Re: Tlt/Trim hydraulic hose replacement on my '79

Thank you so much everyone for the great tips and comments. I'm still a little green on these things :%. As far as the "Early model" reference it was my understanding that there were essentially 3 different setups and the 2 ram setup was/is the oldest. I guess mine may be a one off though as there are only 2 hoses total!? Special thanks to Smig for the manual!!

 

[Plainsman]

Re: Tlt/Trim hydraulic hose replacement on my '79

Plainsman, The PTT cylinders are not self bleeding. I am not sure how yours were able to bleed themselves, w/o help. If you look on the top the the cylinders, there is a bleed screw. If you look on the cylinder, adjacent to where the two hoses attach, there is another bleed screw. Both of these must face up, when bleeding. So you can bleed the down side of the PTT with the cylinders attached (top bleed screw). But you must remove the cylinders and face the Up bleed screw up, to allow the bubbles of air in the cylinder to escape. The procedure is to face the "Up" bleed screws up, remove one of them and run the pump up, until there are no more bubbles. Replace the screw. Now do the other cylinder, replace the screw and install the cylinders. Now remove a down bleed screw and run the pump until no more bubbles. Replace the screw. Now bleed the other cylinder.

I respect your opinon Chris and maybe I didn't do correct, but it works. And thanks for the directions on how do it.

 

[Scaaty]

Re: Tlt/Trim hydraulic hose replacement on my '79

Scatty, over the years merc has recomended just about anything that comes in a oil can, In the early 70s when at service school they said you should not use ATF, after using it for years, so we ask why and the awnser was it will damage the o-rings in the system by causing them to swell. So when returning to the shop we took a can put some ATF and o-rings for the tilt system, the next fall when the service rep. (also the instructer at Fondulac) showed up we showed him that they hadn't swollen a bit and for 4 or 5 years evertime we saw him we got out the can again, he finally through it in the trash and said "There i won't have to ck those damn things again" and we still use dextron--Bob

Have to agree here as I've stick O-Rings in a variety of fluids over the years for experiments, and never had a problem with any swelling. The "rings made today are probably impervious to just about anything...good info, thanks.

 

[Scaaty]

Re: Tlt/Trim hydraulic hose replacement on my '79

This is an installation manual for the two ram system. It may have something that helps

PTT Manual

This is the page on filling and bleeding.
Filling and Self-Bleeding

THANKS! Great links and pix!