Hurth question

My transmission has developed a loud CLUNK sound when it is put into forward. There is a softer clunk when going into reverse. As I recall the sound I am hearing when putting in reverse is the sound I used to hear when putting it into forward.

Any thoughts? The Hurth Model is HSW50 in my E-38-200.

Thanks in advance.

Don Taugher
Running Free # 263
Long Beach, CA

Prop?

Do you have folding or feathering prop by any chance? Could be that and not the transmission.

Cory:

Yes I do have a three blade feathering prop and the thought that you have (the clunking is coming from the prop) has crossed my mind. I dismissed this because the clunk is so loud, but maybe I shouldn't.

I didn't make mention of this before, but the tranny fluid is nice and pink and full to the line, there are about 2800 hours on the engine and transmission.

Don

Does it rattle at all in neutral down near the bell housing? Sounds like a damper plate, prop or something is lose. Does it slip at all?

I was snooping around the transmission yesterday while in neutral, there are no rattles, no leaks, no excessive movement. I have a dripless and all is dry. Also happpy to report there is no slippage.

Any other thoughts? I don't know what a damper plate is, will have to look into that.

Don

Dampers and rattles

Speaking of "damper plates" I often ponder whether the chosen one in a Universal diesel has "looser" springs that rattle more at idle speed than other diesels...

'Swear I can detect a Universal (Kubota engine) idling from 50 feet away...
As to the clunk noise going into gear, we always noticed it for the decade we used a feathering prop -- either direction. When those blades do a 180, there is a quite an audible clunk when they hit the stops.

Below is a picture of the damper for one of the Universal's. This smoothes out the power strokes from each detonation due to the high torque of the diesel engine, if I understand it correctly. It's there to reduce shock wear on the transmission.

Any mechanics that want to check in, Please Do So!

Loren

LOREN, CORY and MAINE SAIL:

Thanks for your responses, I'm still considering all options. Main Sail and Loren mentioned the damper plate, if that is the problem, do you expect the clunk sound would be the same for forward and reverse? If I were to describe the sound I hear when putting the boat in reverse as a CLUNK, I would have to describe the sound when putting into foward as a SLAM.

I really hope it is the feathering prop, but wow the clunk (slam) is loud.

Any thoughts?

Don

Hurth Problem Resolved E-38

At long last I can report on the CLUNK (and slam) I was hearing when shifting into forward. Thanks to Cory, Main Sail and Loren for chipping in their comments, if there were a prize it would go to Cory for his suggestion which hit the mark.

Although Cory suggested looking at the feathering prop, I started above water thinking it was the transmission. I called in the local Universal and Hurth specialist for his opinion. He gave the transmission a clean bill of health but noticed the engine mounts were loose, so he took the opportunity to align the shaft to the engine and adjust the mounts. There is no doubt in my mind that this service was needed, but the annoying clunk was still very audilble.

Next I had the diver who cleans the hull monthly look carefully around the feathering prop. When he pushed and pulled and moved the prop around, he noticed a gap could form between the two hub assemblies.

Next I contacted Martec for their opinion. They were fairly certain that three internal bolts worked loose allowing the prop assembly to pull away from the shaft assembly when put into reverse, then when put into forward the prop assembly slid forward making hard contact with the hub assembly, possibly resulting in the loud clunk I was hearing.

Martec's assesment was correct, the problem was resolved without having to haul the boat. The key was a good diver and a long "T" handled 5mm allen wrench to reach the bolts which had worked loose. Working under the boat he was able to keep every thing aligned and secure the bolts.

What caused the screws to loosen? I had a drip-less and new shaft installed at my last haul-out in 2008, upon re-assembling the feathering prop, the yard failed to use "red lock-tite" as specified in the instructions. With time the screws worked themselves loose.

All is well that ends well, so I'm a happy camper and sailing again.

Don Taugher
Running Free
E38-200 # 263