Lost Forward and Reverse (Hurth HBW 250)

[rabrown10]

While sailing I noticed that the prop was turning while I had the shifter in reverse. I Started the engine and there was not any engagement in forward or reverse. The shift cable was working properly. I noticed a small pile of metal filings under the bell housing and a metalic sound when I turned the prop shaft by hand.

Looking for any experience with damper plates before I tear into the job. Could that be the cause of a complete failure of power transmission?

[Zach]

I've had the key shear on the transmission side of the shaft coupling, shifter worked forward and reverse but the propeller shaft didn't move. Are your metal chips back under the shaft or elsewhere?

If they are under the shift lever is it possible the lever is moving but the shaft it rides on is not.

Hopefully its not internal!

Good luck!

[rabrown10]

Thanks for the reply. Chips appear to be from a small at the bottom of the shroud surrounding the flywheel/damper plate. Shifter lever arm is tightly connected to the shaft going into the transmission and the prop shaft coupling key is intact.

[SkiprJohn]

Damper plates can fail. It would require separating the bell housing from the transmission to investigate if that is the case. There are more experienced folks on this forum who know more about it but it happened to a friend of mine who was doing a Pacific crossing. The engine will run and the shifter works but no forward or reverse because the trans is not connected to the flywheel if the damper has broken.
Kind regards,
JohnL

[Alan Wheeler]

Sounds like a possible. And running the box in gear wouldn't have been the cause. It just happened.

[perchance]

Sounds like the damper plate ate the splines on your input shaft or the plate itself. I have seen this on the hbw 100. Turns out the springs in the damper plate were too stiff. Running the engine consistently at low rpm can cause excessive wear due to the pulsing of the engine at low speed. The constant change in spline lash does the damage.

[DeepFrz]

It would have been nice to hear from the OP what the resolution was, 3 years ago...

[rabrown10]

Woops. I thought I posted the resolution.
The damper was destroyed - springs were in pieces. Changed damper plate and have been running smoothly ever since.

Cause of destroyed plate was an unbalanced prop which I did not address soon enough. Splines were fine.