Trim done gone berserk...

[oldmako69]

One of my 2005 YAMAHA FOUR-STROKE F225TURD engines took a large excremental this afternoon. I wandered out to the very end of the no-wake zone and then proceeded to get my giddy-up on with some significant acceleration. Yot then proceeded to climb out and haul donkey. I nosed the tabs down a bit and then reached for the engine trim.

When I trimmed the engines UP, the port engine lifted significantly along with a corresponding change in RPM. This was followed by a thunk as I released the switch a nano-second later. I was looking ahead at this point and had no idea what had just happened, so I spun around and tried it again. Exact same result.

Whiskey Tango Fox? It would seem to me, being an idiot, that the force of the prop pushing the boat at 4300 is going to create a hell of a "engine trim down" moment. But when I hit the trim switch, it was as though I had gotten Cro-Mag with reverse thrust and pulled the prop aft.

I thumbed it down a touch and it responded correctly. I then bumped it up again only to be disappointed again.

Learn me what I gotta do. Never a dull moment with these old TURDs.

[99yam40]

I am not sure if you have been drinking too long or me, cuz I have no idea what you are trying to tel us it is doing? Is it banging back down when you let off the switch?

[oldmako69]

The easiest answer is that I don't really know.

When trimmed up from fully down, it doesn't slowly and smoothly raise like its supposed to. It lurches upward dramatically and instantly. Nothing smooth or con*****ed about it. Needless to say the application of UP trim results in an immediate change in pitch (engine rpm) and roll about the boats longitudinal axis. As a result, the engine only pops up an inch or two because it startled the hell out of me and I release the switch. When released the engine slams back down right now. With a thunk. Clearly AFU. It is very TURDish.

That make more sense?

[99yam40]

never heard of anything like that before. do not know how the T&T can move suddenly like that

[oldmako69]

Perhaps now you can appreciate why I used the word berserk.

I haven't spent much on my engines lately. Of course, I haven't really been using the boat much in the last 60 days either. I guess I was due. Silly me.

[pstephens46]

First of all, isn't it about time in VA to put that thing up for the winter?

Can't remember. Does it come out of the water regularly? Just for Shts and GIggles, try to add fluid. Maybe there is some check valve that Rodbolt can address.

[oldmako69]

I don't winterize my boats. I won't use it as much, but there can be excellent winter fishing here. Specks now, schoolie striped bass on / off all winter long depending on temps and where they end up....anywhere from here to North Carolina. Historically we'll see the big 40-60 pound breeder cows show up as well. A few years ago, there was a nice run of big Bluefin mixed in with them, right off the beach. And with luck, we get a nice display of Humpbacks.

The boat spends most of its time on the trailer. It's not bottom painted and I already have enough maintenance issues to deal with.

The fluid was my first thought as well. Seems to me that it must form a HYD restriction to keep it in one spot and the only way to move that restriction (and the engine along with it) is by actuating the switch. But I dunno. I use Hydraulics all the time at work, but I don't wrench on em.

What fluid is in the trim actuators? Generic HYD or 50 dollar a quart Yam?

[fairdeal]

What fluid is in the trim actuators? Generic HYD or 50 dollar a quart Yam? :

Your Service Manual "recommends" Dexron II
but yes, the true Yamaha enthusiast can buy "Yamalube Performance Tilt & Trim Fluid"
which they can use while wearing their Yamaha hat, Yamaha Tee, and Yamaha sunglasses....

[99yam40]

Your Service Manual "recommends" Dexron II
but yes, the true Yamaha enthusiast can buy "Yamalube Performance Tilt & Trim Fluid"
which they can use while wearing their Yamaha hat, Yamaha Tee, and Yamaha sunglasses....

good luck finding Dexron II, but you should be able to find III or is IV now

[pstephens46]

My one Yamaha hat blew off boat and disappeared several years ago. My decals are starting to peel a little. In a couple years, there may be no mention of Yamaha on boat except for grey paint.

[pstephens46]

good luck finding Dexron II, but you should be able to find III or is IV now

Or Oldmako could use a little of the pallet jack fluid he uses in Seastar steering.

[oldmako69]

Or Oldmako could use a little of the pallet jack fluid he uses in Seastar steering.

I may get over there this afternoon. I'll put that suggestion at the top of my list, since it's already banging around in the back of my truck.




*Not actually my truck.

[pstephens46]

I may get over there this afternoon. I'll put that suggestion at the top of my list, since it's already banging around in the back of my truck.




*Not actually my truck.

I just figgered your girlfriend put your sht out in the yard again....

[oldmako69]

She can't. It's my crib.

[zenoahphobic]

For the engine to jump up, greater than the speed the trim would normally be able to push it, suggests that when you applied the switch it also simultaneously reduced the power of the engine, and the trim rams offered no resistance, like they should, to the engine kicking up (in this instance by the water from a momentary loss of power, more so because the second engine continues to push).
Could this be two faults, one electrical and one hydraulic? The hydraulic could have existed for a while but a resistance or load resulting in a significant voltage drop can cause strange results to the running of the engine.