Yammi pops out of water in reverse when gassed

[iltfish101]

Hi Folks-I ran into a problem yesterday with my engine that I have never seen before. I am in a new marina with strong currents, so I need to give it some gas when in reverse to get into the slip. When I did this yesterday, the engine kicked out of the water and slammed back down when back in idle reverse. It did this a few times, but I eventually got into the slip. This worries me as I have never seen this before.
It’s a 1999 S200TXRX Saltwater series. The trim tilt seals were replaced last year for leaks. I did check that the manual release/bleed screw was tight. I also checked the trim tilt fluid level and bled the system by raising electrically and lowering manually with the bleeder screw a few times.

If anybody has encountered this before or has some suggestions, I would greatly appreciate it. I am going to talk to my local Yamaha mechanic this week, but figured I would ask here also. Thanks in advance!!!!

[99yam40]

there are spring loaded check valves in the system that should keep the motor down when reversing, but pop open when lower unit hits a solid object while underway.

maybe they are stuck open or did not get reassembled properly if they were removed

[iltfish101]

Exactly where are these check valves located?
It was only the seal on trim tilt rams that were replaced.

[rodbolt17]

all yall nuts?
has the world gone mad?
ANY motor when gagged hard in reverse pops up and as soon as you let off it drops to its last trim/tilt position.
the valving doesn't know, nor does it care, why the lower is trying to come up.
all it knows is that a pressure to raise the motor has been met and it releases.

[pstephens46]

My motor has never done that.

[boscoe99]

My motor has never done that.

Never heard of any Yamaha doing that. Don't think the reverse thrust is enough to get the job done. Not in a LU that is working per design anyway.

Lots of motors get slammed into reverse at high speed causing the motor to rotate backwards and suck up water. Never heard of any of them causing the relief valve to open and allow the motor to swing up.

Oh well.

[panasonic]

all yall nuts?
has the world gone mad?
ANY motor when gagged hard in reverse pops up and as soon as you let off it drops to its last trim/tilt position.
the valving doesn't know, nor does it care, why the lower is trying to come up.
all it knows is that a pressure to raise the motor has been met and it releases.

Rodbolt, if the hydraulics are working properly does the motor go back down hard? He says his is slamming back down....
I understand that it will pop up fast when LU is stuck or too heavy on the gas in Rev. But should it not slam back down?

[99yam40]

My C40TLRX does not do that either,
even when I shut down in shallow water, the motor just stops the boat when it digs into the mud/sand. never seen it raise up.

maybe mine are stuck closed

[rodbolt17]

trust me it will IF the pressure on the up relief valve is met. most tiny motors have to be gagged hard, my F150 will release at about 3500 RPM in REVERSE.
how I found that out is a long interesting story and alcohol may have been involved.
even the locks on non T&T motors will release if the up pressure is met.

[fairdeal]

perhaps with "sufficient" reverse thrust the "tilt piston impact relief valve" will open - just as it would if striking an object while moving forward.

my F225:

[pstephens46]

trust me it will IF the pressure on the up relief valve is met. most tiny motors have to be gagged hard, my F150 will release at about 3500 RPM in REVERSE.
how I found that out is a long interesting story and alcohol may have been involved.
even the locks on non T&T motors will release if the up pressure is met.

Hope no one was watching.... bet you scared the crap outta yourself when that exhaust popped out of the water!

[panasonic]

Maybe one of you fine gentlemen would like to test this out and see if it happens.Most on this thread seem to think it will not.

I would do it but my small engine has mechanical Reverse locks and I don't have access to my F60 with trim/tilt right now...

Any takers?

[boscoe99]

Over on another site they are complaining about how poor their propellers are performing in reverse. I guess they wish they had the problem where the reverse thrust is so great that it breaks the hydraulics loose and allows the motor to tilt up.

Now if a motor does get kicked up by hitting an object then a metering valve in the tilt piston should slow down its rate of fall. The tilt piston should return to the position that it was in before the lower unit strike, but slowly given that fluid has to cross a metering valve.

Op says his "slammed back down when in idle reverse".

Seems that this is new to him but what is not known is if his shifting into reverse pattern has changed. That is, is everything the same but for the motor now lifting up when he is in reverse? Motor never did it before, motor is now doing it, but it is a characteristic of the motor?

Colour me confused. Put me in the category of thinking that it should not happen. In a unit that is working correctly that is.

Now another question may be, why did my lower unit get damaged when I hit a piece of concrete at 50 Km/Hr? Why didn't the lower unit work as it was supposed to have and allowed the motor to tilt up, thus avoiding damage? The lower unit was faulty and I think Yamaha owes me a new motor. And damages for emotional distress.

[TownsendsFJR1300]

My C40TLRX does not do that either,
even when I shut down in shallow water, the motor just stops the boat when it digs into the mud/sand. never seen it raise up.

maybe mine are stuck closed

My F150 does the same as yours 99...

Never revved in reverse to 3,500 so can't comment about that...Didn't think it would rev that high in reverse....

Smacking back down hard does NOT sound normal.

Per Fairdeals post, with the valving, it sounds that even if the motor is forced up, it should NOT fall down immediately, but somewhat slowly, (or slower).

For the Op, does it do that NOW all the time and BEFORE, did you notice it at all?

.

[pstephens46]

I have done some hard reversing and never had it pop. Pulling into a narrow long slip with the current pushing on your stern requires a quick 180 degree turn to dock against the same current. Never looked at the tach, way too busy trying to NOT make a fool of myself. We have 6-9 ft tides here.

Wonder where the OP is located? Has he disappeared?