Hydraulick oil for tilt/ trim 1996 75 HP Merc

[Dennis G]

I accidently lost about 20% of existing oil. It is red so I'm guessing power steering fluid is in there now. Should I just add more power steering fluid or is there something better? Easy enough to drain and replace all if necessary. Thanks, in advance, for all replies.

 

[Chris1956]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

I would top it off with some Dextron ATF.

 

[Chris1956]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

BTW - Power Steering and ATF are the same stuff.

 

[Dennis G]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

BTW - Power Steering and ATF are the same stuff.

I was told that Trans fluid foams under heat/pressure and Power Steering fluid does not. Is this true? Should I just top off with Power steering fluid (of which I have) ? Thanks. DG

 

[Dennis G]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

Filling w/ power steering fluid. Fill screw is close to bottom of motor. After leveling my boat to level the tilt motor, do you just fill, lift and lower 5 times to bleed and then refill to this yellow screw level?

 

[RRitt]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

since you are topping off, chances are good that you don't need more than one or two cycles of up-down.

top off, run up direction, and top off again.
once the engine is fully raised and topped then put in plug (fingertight is adequate)
cycle the trim fully lowered and fully raised.
check fluid level.
If it is still topped off then your are done.

 

[Texasmark]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

My service manual for a like kind engine (90) says to look at the fluid in the reservoir. If clear use quicksilver PTT fluid. If red use ATF.

Mine is clear and I use QK PTT fluid like the manual says. Does it matter? I don't know. I didn't design it and not a petroleum engineer.

Mark

 

[Chris1956]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

Mark, I will bet QS orders ATF without the dye.

 

[RRitt]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

there is an oil specifically engineered for hydraulics. It is called "Hydraulic oil". It is what they use in the big multi-million dollar factories, mining operations, commercial fleet, etc. ATF, if you use the right type, is just as good in most recreational marine systems. ATF has about the same viscosity as ISO32 hydraulic oil. Hydraulic oil is the color of light honey. Hydraulic jack oil from autoparts is the same or similar to ISO32 but without the guarantees of precise formulation. Actual H.O. has additives to maximize the performance and lifespan of rubber seals while minimizing foam and absorbing transient moisture. You should never confuse DOT brake fluid with hydraulic oil. It will ruin your brakes and/or your trim if the two mix.

Some trim systems call for 10w, 20w, or 30w motor oil. You should never, ever use motor oil with additives. A better choice for these older systems (but extremely difficult to find) would be hydraulic fluid with a viscosity rating of iso64 or higher.

another variation on hydraulic oil is AW32 and tractor fluid. Tractor fluid is the HO equivalent to Dextron. It is a hydraulic oil engineered to be a decent enough ATF substitute. AW32 is an all weather oil engineered for use in a canadian winter. It is great for snowplows and such.

In my shop, i always reach for ISO32 first. I take pride in my work and want it to last as long as possible.

 

[Chris1956]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

What he says, and let me add that brake fluid is the color of tonic water and lime juice. However, it is not nearly as good to mix with gin!

I always reach for the tonic first (smile).

 

[Dennis G]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

My service manual for a like kind engine (90) says to look at the fluid in the reservoir. If clear use quicksilver PTT fluid. If red use ATF.

Mine is clear and I use QK PTT fluid like the manual says. Does it matter? I don't know. I didn't design it and not a petroleum engineer.

Mark

The existing fluid in my tilt pump is RED. I quess I'll go with topping off with Dextron (lll)? I have Detron Vl for my GMC truck but not sure if that is the same as Dextron lll,

 

[Texasmark]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

Mark, I will bet QS orders ATF without the dye.

Like I said man, I don't know.

Mark

 

[Texasmark]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

The existing fluid in my tilt pump is RED. I quess I'll go with topping off with Dextron (lll)? I have Detron Vl for my GMC truck but not sure if that is the same as Dextron lll,

Now that I am getting 100k mile warranty on my truck power trains and they specify Dextron VI, gonna betcha it's synthetic, just like the rest of the fluids in the power train including the engine. About time Detroit got their act together. Too bad it took Big Brother to turn GM around. I bought after the take over and Chevy ain't what it used to be. A fine machine.

Mark

 

[RRitt]

Re: Hydraulick oil for tilt/ trim 1996 75 HP Merc

Now that I am getting 100k mile warranty on my truck power trains and they specify Dextron VI, gonna betcha it's synthetic, just like the rest of the fluids in the power train including the engine. About time Detroit got their act together. Too bad it took Big Brother to turn GM around. I bought after the take over and Chevy ain't what it used to be. A fine machine.

Mark

the worry with using automotive formulations in hydraulics is with the additives. Trim hydraulics operate at pressure up to 2800psi. At these pressures, many of the automotive additives become harmful to Nitrile rubber. You should never, ever, ever use any type of fluid with additives in your hydraulic system. I also have doubts that synthetic would hold up under the pressure and shearing forces of hydraulic systems unless it is a type that has been specifically designed and tested for use in hydraulics.