175 HP v-6 Tilt/Trim stuck in down position

[P51D]

I have a '91 or '92 Mercury V-6 175 HP 2.5 litre. Serial #OD223009. 3 days ago, the tilt/trim stuck in the full down position. Before that, everything worked fine, but we?re probably only talking about 6 or 8 full up and down cycles this boating season.

The pump motor sounds like its running fine, but with little or no load. There is definitely hydraulic fluid leaking. So I pulled the boat out of the water today to look things over. With some excellent advice from J Martin (from this forum), I was able to muscle the motor up and lock it in the up position by unscrewing the manual release valve 3 - 4 turns, then engaging the tilt lock. As I pulled the engine up manually, venting sounds occurred and pink fluid leaked out. It dripped from the bottom of the starboard side of the manifold assembly. That is, from the bottom of the starboard trim cylinder. That?s where it dripped from, directed by gravity, and I still have not identified the source of the leak.

I expected to see the leak at the top of the tilt or trim cylinders, where the piston rods exit. Just seemed to be the most logical place since all else below those points seem to be solid cast metal. Or are they? The diagrams in the Mercury manual are not helping me form a good picture of other potential leak points.

Any advice on tracking down the leak point, since it doesn?t seem to be from the top of any of the tilt or trim cylinders?

Any advice on how to put more fluid in?

And what fluid to use?

I?m headed back to the manual now to hopefully find some answers, but if anyone can chime in, it would really help me out!

THANKS

 

[P51D]

Re: 175 HP v-6 Tilt/Trim stuck in down position

OK, I answered some of my own questions, and maybe this info will be useful to others:

Type of fluid to use on this system: Type F, FA, Dexron II, or Dexron III fluid can all be used, per the Mercury manual.

Add the fluid with a "squirt-type" oil can (The type where you screw the top off, add the oil, replace the top, and squeeze the lever/trigger to pump the oil).

Any advice on likely leak points? It doesn't look like it's leaking from the top of the tilt/trim cylinders, nor around the rams, nor from the manual release valve, nor from the fill cap.

THANKS

P51D

 

[P51D]

Re: 175 HP v-6 Tilt/Trim stuck in down position

Any help from the gurus will be appreciated. There are at least two of us with the same problem within the last two days. Michael/Scott87's problem sound similar to mine.

Thanks

P51D

 

[Chris1956]

Re: 175 HP v-6 Tilt/Trim stuck in down position

They can leak around the base of the motor, as well as the manual release. And if something broke, they can leak from other places.

Why not look to see where is is leaking from.

 

[P51D]

Re: 175 HP v-6 Tilt/Trim stuck in down position

Chris - THANKS. I have been looking all around to see where it's leaking from, and so far, I only see oil coming from the absolute lowest point of the whole trim assembly, down around what the manual calls the "shaft assembly".

Originally, I assumed the leak was higher up, and it was dripping down. I put more oil in today, and ran the trim motor, and now it looks like the origin of the leak IS somewhere near the bottom of the whole trim assembly. Does the "shaft assembly" act as a pipe through which the pressurized oil moves from the starboard side, where the pump is, over to the tilt cylinder and port trim cylinder? If so, it now makes sense to me that that is the origin of the leak. Is that common? Bad O-ring on the shaft assembly?

I don't mean to be dense. I've just never dealt with a tilt/trim system before, and while the merc manual is good, it doesn't exactly do a good job of explaing what parts do what.

THANKS. All help appreciated. P51D

 

[MichaelScott87]

Re: 175 HP v-6 Tilt/Trim stuck in down position

Now I'm lost. I had the post about the same problem last night. Yesterday when I went to lower it to flush it it wouldn't go up. Today I bought fluid and went to fill it (while the motor was up of course) and it was completely full. Not only was it full but the motor is working fine and not leakeing from anywhere. I raised and lowered it 15-20 times without fail. It makes me nervous because I'm taking the boat to Hatteras for a week tomorrow morning and I'm afraid I have a false sense of security. I'm thinking for some reason it was simply stuck when I went out yesterday. Still there has to be some mechanical explaination for this.

 

[P51D]

Re: 175 HP v-6 Tilt/Trim stuck in down position

Michael - your case and mine sound like they started with the same symptoms, but they are definitely different now. Mine took about 8 oz of fluid to fill up, and when I sealed the fill port and manual release valve, and then operated the trim motor, fluid bled profusely out of the bottom of trim/tilt assembly.

You mentioned that you saw evidence of oil on the water. Of course, just one drop of oil will make an impressive rainbow on the water. So you see no leaking of an oil leak at all now?

I wonder if you had a clogged port somewhere that somehow got unclogged?