Mercury Tilt-Trim (2 cylinder)

[imported_Voyager]

I'm "new" to old Mercury motors, and have a 50hp in-line 4 from 1982 (an "M50"). Bought this for a boat I'm restoring; It was listed on ebay as a parts motor that was running on two cylinders. A trigger, carb kit and impeller later, it is now up and running.

I'm puzzled about the two cylinder Tilt-Trim; Outboards I've had experience with in the past had the newer 3 cylinder arrangement.

The pump has a "selector" knob that is labeled "reverse lockout". The label on the pump says what to do with the knob (engage or disengage for running the boat, I forget which). That's clear enough, but can someone explain what screwing the knob in/out actually does?

I just got the pump hooked up and have been cycling it to bleed the system (making progress), and was wondering if the reverse lock should be one way or the other to better bleed the air out. I removed the bleed screws to flush/bleed, then put them back and will proceed by cycling up and down.

Any wisdom would be much appreciated. THANX

 

[Chris1956]

Re: Mercury Tilt-Trim (2 cylinder)

The reverse lock release knob allows you to tilt the motor up by hand. It is still difficult to do, however. The cylinders are not self bleeding. Have you found the "up" bleed screws on the cylinders next to where the hoses connect? The bleed srews on the top of the trim cylinders are for bleeding the down hydraulic circuit.


BTW - the reverse lock should always be engaged unless you are hand-tilting the motor.

 

[imported_Voyager]

Re: Mercury Tilt-Trim (2 cylinder)

Thanks, that (reverse lockout) makes sense. On bleeding the system:

I found the bleed screws and ran till I got some juice out of them (both up and down). I was working alone, so couldn't get the plug in right away. The (Seloc) manual mentions locking the motor up, then "cycling thru several full cycles", (with the vent plug out) which doesn't really make sense to me, if it's locked in the up position, it isn't going to do any "cycling".

The trim is running but is still a bit jerky, and the motor can be pushed down, so I must still have air. The manual made it sound like the air would work its way out just running the motor up and down; What is the proper procedure?

 

[Chris1956]

Re: Mercury Tilt-Trim (2 cylinder)

The pump itself is self bleeding. You must manually bleed the cylinders. Here is the procedure:

Fill the trim pump with 5w-30 motor oil (or Dextron III ATF, if that is what you are using)

Motor fully down - Remove one bleed screw from tehtop of one cylinder. Run pump in down direction until no bubbles in the oil that shoots out. Reinstall bleed screw. Remove and repeat with other down bleed screw.

Now remove cylinders from the OB. the up bleed screws are next to the spot where the hoses attach. The bleed screws must face upward to allow the air to bleed out. Secure the cylinders so the bleed screws face up. Remove one bleed screw and run the trim pump in the up direction until all the air bubbles are out. Reinstall the screw and repeat with the other cylinder. Reinstall the cylinders and refill trim pump. You might like to cycle the motor up and down a bit to bleed the pump as well.

 

[imported_Voyager]

Re: Mercury Tilt-Trim (2 cylinder)

Many Thanx! I had enough hose to be able to just disconnect the top and swing the cylinders back and down to get the bleed hole up. That did the trick...