Thread: Tilt/Trim problem ... 1999 90hp Merc 2strk

Loosen the bleed screw, rise it all the way up, then let it fall back down slowly. You will have to do this several times to bleed air out and your probably going to get tired. But just take your time and you will eventually get it bleed. After 2-3 times with it all the way down check fluid level. May have to add a little after the air bleeds out.

Originally Posted by Cray

Loosen the bleed screw, rise it all the way up, then let it fall back down slowly. You will have to do this several times to bleed air out and your probably going to get tired. But just take your time and you will eventually get it bleed. After 2-3 times with it all the way down check fluid level. May have to add a little after the air bleeds out.

Thanks Cray ... I'll give that a shot as soon as the bruises on my arms go away

Actually I asked about doing that at the dealer & I understood him to say to use the switch to move motor up/down ... and not do it manually. Maybe I misunderstood
Anyway ... I'll give your way a try ... appreciate it, buddy !!

Originally Posted by Cray

After 2-3 times with it all the way down check fluid level. May have to add a little after the air bleeds out.

Can you clarify this ?? If the big motor is "all the way down" how am I going to get to the fill port screw to take it out and add fluid

If that is the case, take it all the way up. Lock it and slowly remove plug. You are trying to vent the air out of the system and that’s the only spot it can get out. May just be a tiny bit each time but eventually you will work it out to where you can move it with the pump.

OK .... so you're saying to loosen the release screw .... lift & lower the motor 2-3 times manually ... then lift it & lock it and open the fluid port and check/add fluid ... repeat process ~10 times ... then try using the trim switch to move motor up/down. Is that right ??

My question then would be ... should I leave the release screw loose during the process, until I try the switch ?? Or should I close the release screw before opening the pump port screw & checking the fluid level ?? Or do I have to close the release screw at other points in the process, too ??

I'm not familiar with your tilt and trim unit but on any hydraulic system that I have ever bled, like on a triaxle dump truck, and I've bled a bunch of them, you'd raise it as high as it would go with the controls, then open the bleeder screw and let it bleed down until fluid started coming out. Repeat that several times, sometimes many times. If it works the same way on a boat, and you open the bleeder screw to raise the motor, you're going to get more air in the system.

Originally Posted by FurFlyin

I'm not familiar with your tilt and trim unit but on any hydraulic system that I have ever bled, like on a triaxle dump truck, and I've bled a bunch of them, you'd raise it as high as it would go with the controls, then open the bleeder screw and let it bleed down until fluid started coming out. Repeat that several times, sometimes many times. If it works the same way on a boat, and you open the bleeder screw to raise the motor, you're going to get more air in the system.

If you don't open the bleeder screw on a tilt/trim .... you ain't gonna move the motor manually !! And try as I may, the switch will not move the motor in either direction (like it's supposed to) .... and if/when it does move it in one direction, it won't move it in the opposite direction. The best it's done is trim the motor down (at a normal pace) ... it struggles to trim the motor up (if/when it moves up at all). My marine mechanic says it sounds like air lock .... as air compresses easier than fluid, so the air has to be bled out & the fluid level maxed out so that the pump is compressing fluid only. At least that's how I understand it.

If it will only go down under power, swap the wires on the relays and see if it starts moving in the other direction. If it does, swap them back and see if it reverses the direction. If it does, you have a bad relay. Been there, done that, chased my tail for a week because they both lit up a test light like they would if they were good. Green wire is the hot wire to the down relay, blue wire is the hot wire to the up relay. You probably already know all of this but when you swap the wires, pressing down will work the up side, and up will work the down side.