Engine leaks down (tilt, not trim)

[DennisG01]

The engine is starting to slowly leak down after it's been completely tilted up. I can tilt it up, and then the skeg will drop a couple inches within a minute. It then stays put. BUT, if I stand on the anti-vent plate, it will drop all the way to the trim rams, but no further.

-- The reservoir was a little low so I put Dex III in it and then ran the motor up and down. I repeated the process about 6 times since the existing fluid was a little dark. That made no difference.

-- I double checked the manual release by loosening it and tightening it. That made no difference.

-- I see no visible leaks anywhere.

And, finally, my questions

1) I looked at the parts diagram for the manual release and it appears there is an inner o-ring and a "manual valve seat" that could possibly be the culprits. Does this sound reasonable?

2) Can the manual release "components" all be removed through the hole that the manual release screw resides in, or does the entire trim/tilt assembly need to be removed? In just looking at the diagram, it appears getting some of the components to come out could be challenging. If the latter is the case, I'll probably just use the tilt support lever when the boat is on the mooring (not a big deal).

3) If I did remove it, am I correct that most, if not all of the tilt fluid will drain out? No big deal if it does - might help get some of the small components out and also function as a "drain/flush".

[DennisG01]

Following up on this, and thinking a little more... The problem can't be the manual release valve since the engine only lowers by itself a few inches and if I put downward pressure on the lower unit, the engine will stop lowering when it gets to the trim rods (even with downward pressure, it won't go any further). Am I correct in my line of thinking?

I looked in the manual at the "trouble shooting" section and under "Looses tilt holding", it gives 3 options... Up & Down Relief Valve, fluid level and fluid passage. I assume by "passage" they mean something is clogged? I will check the fluid level again and be sure I don't have any air in the system. I have not noticed any leaks, though. Other than the slow drop, everything operates fine.

The Relief Valve appears to be under the fluid resevoir and it maybe I can remove that without removing the bracket assembly, which entails removing the engine? Is there a rebuild kit for this, or do I just buy the various o-rings, filter, valve seals?

Could anything else be causing this issue, or is the Up & Down Relief Valve the most likely culprit (assuming fluid level is good)?

[zenoahphobic]

As far as I have experienced that manual relief valve also releases the trim rams. I would expect those rams offer a far greater resistance, and the weight leverage of the engine becomes significantly less. Testing under thrust to see if they give way would be my test for that valve.
Nonetheless I expect the unit needs to be pulled apart and cleaned and all valves inspected, someone in the know will give a proper diagnosis.

And I was thinking if you released that valve and operated the tilt trim switch up and down, that the circulating oil may clear a possible blockage. Previous threads have other suggestions like manually rocking the engine etc., for getting a valve to seat properly.

[TownsendsFJR1300]

"Passage" to me, sounds like something ISN'T sealing / holding pressure.

That would make sense as the fluid is leaking internally, not holding the engine up.

Seals, rubber, etc, fail over time.

RB should know what valve or likely part is your issue...

[DennisG01]

As far as I have experienced that manual relief valve also releases the trim rams. I would expect those rams offer a far greater resistance, and the weight leverage of the engine becomes significantly less. Testing under thrust to see if they give way would be my test for that valve.
Nonetheless I expect the unit needs to be pulled apart and cleaned and all valves inspected, someone in the know will give a proper diagnosis.

And I was thinking if you released that valve and operated the tilt trim switch up and down, that the circulating oil may clear a possible blockage. Previous threads have other suggestions like manually rocking the engine etc., for getting a valve to seat properly.

Yes, I am positive that the manual release valve controls the trim rams, as well as the tilt ram. That's an interesting point, though... does it take a greater amount of force to collapse the trim rams. I'm trying to recall that when I've used a manual release valve in the past on this engine (or other engines) if I had to open the release valve further when the engine got to the trim rams... but I can't remember well enough. Good idea on clearing a blockage - thanks!

[DennisG01]

"Passage" to me, sounds like something ISN'T sealing / holding pressure.

That would make sense as the fluid is leaking internally, not holding the engine up.

Seals, rubber, etc, fail over time.

RB should know what valve or likely part is your issue...

Interesting... you took that "passage" to mean a "leak" and I took it to mean a passage"way" that is blocked. Interesting how the same thing can be taken two different ways... of course we have the added complexity of deciphering something that was already deciphered from Japanese...

I came across something on the 'net where they were able to get the entire pump/ram assembly out without first removing the engine. Raise the engine, use the tilt rest/lever, remove the tilt ram pin, then lower the tilt ram, then lift the assembly up and with a slight twist remove the assembly. I'm paraphrasing, but that's the jist of it. I wasn't able to really get a good read/confirmation, though, on how accurate that statement is.

[TownsendsFJR1300]

In it's text for potential issues: "Up & Down Relief Valve, fluid level and fluid passage" .

IE, Relief valve bad, low fluid level and/or FLUID passing when it shouldn't..


**Most of the T&T units come off the bracket just as you stated above.
If you look at the parts fisch, that should help (and simply looking at it) as to how the unit comes off..

[rodbolt17]

I wonder which of the many different units Yamaha made is being discussed?

[DennisG01]

The parts diagrams in my service manual only shows the assembly already removed, so it's hard to judge based on that. Also, I "think" the bracket is slightly different from the OX66's to the newer F-series. Meaning, I believe the bracket on the F-series is designed differently to be more "open" so that the trim/tilt assembly comes out very easily. But, I'm kinda just basing that on bits and pieces of information.

[DennisG01]

I wonder which of the many different units Yamaha made is being discussed?

Is my signature not showing up again for some of you? It shows for me, but I know there were (are?) issues since the new forum.

It's a 2000 Yamaha OX66 250HP SX250TXRY 61AX103847T

[TownsendsFJR1300]

No, the signature isn't showing, mine is gone too...

It's this unit: http://www.boats.net/parts/search/Ya...BLY/parts.html

[DennisG01]

No, the signature isn't showing, mine is gone too...

That's strange, as I can see yours as well as mine. Weird. Gotta luv technology!

Thanks for the link!

[rodbolt17]

tilt leak on the 61-A
free piston oring
tilt piston oring
up main valve.
manual release valve.
my first bet would be on the tiltand memory piston orings and valves.

[DennisG01]

Thanks, Rod. Is it safe to assume then that the first step would be to disassemble the tilt assembly and replace all the o-rings?

By the way, what do you mean by "61-A" and the "memory" piston?

[rodbolt17]

61-A is the model of the unit. the memory piston rides just below the tilt piston and follows it until a fwd impact.
at impact the memory piston sits in its original location while the tilt piston moves up then drops back onto the memory piston.