Hurth HBW 150

[Patman]

We have a gremlin. Twice now when I put our Catalina 380 into gear I hear a loud grinding/squeal noise and feel a vibration under my feet. It does not always happen but has happened once while leaving the dock and once while waiting for a drawbridge to open.

On the latter it actually killed my engine. I quickly dropped it out of gear and cranked the motor right up. Back in gear same thing happened. We managed to limp back to the slip under idle speed. I've messed with it in the slip putting it in and out of gear and she works fine.

Thought first it was a cutlass bearing but that will not stall my engine. Now I'm thinking the transmission.

Does anyone have any thoughts?

[wingless]

How does the transmission fluid look?

When fluid is extracted from the bottom of the sump, how does that fluid look?

The transmission uses internally-created high-pressure fluid and the spool valves to actuate / hold the appropriate clutch packs engaged to route engine torque to the propeller. Contamination, such as from a failed cooler can interfere with proper operation of one or more of those systems.

[Sailmonkey]

Originally Posted by wingless

The transmission uses internally-created high-pressure fluid and the spool valves to actuate / hold the appropriate clutch packs engaged to route engine torque to the propeller. Contamination, such as from a failed cooler can interfere with proper operation of one or more of those systems.

No it doesn’t. An HBW150 is a mechanical gear that uses engine torque to mash the clutch discs together. There are little balls that roll on ramps, these ramps act to squeeze the clutches together more tightly the more torque is applied.

These little gears aren’t even cooled!

The usual telltale signs of a ZF/hurth box nearing its end are a burnt smelling fluid with a lot of suspended shiny particles.

If things are getting particularly sticky inside the box from lack of oil or badly contaminated oil you may actually have astern and ahead clutches stuck at the same time.....killing the engine.

[Uncle Bob]

Originally Posted by Patman

We have a gremlin. Twice now when I put our Catalina 380 into gear I hear a loud grinding/squeal noise and feel a vibration under my feet. It does not always happen but has happened once while leaving the dock and once while waiting for a drawbridge to open.

On the latter it actually killed my engine. I quickly dropped it out of gear and cranked the motor right up. Back in gear same thing happened. We managed to limp back to the slip under idle speed. I've messed with it in the slip putting it in and out of gear and she works fine.

Thought first it was a cutlass bearing but that will not stall my engine. Now I'm thinking the transmission.

Does anyone have any thoughts?

Thoughts, oh yeah, PRM replacement gearbox will eliminate all the woes. You can guess how I have come to this conclusion. I have my old hurth sitting on the garage floor, been there for a couple of years now, several reputable and knowledgeable boat mechanics offered to rebuild it but both suggested the PRM was a far better option. A$1600.00 to rebuild, A$2000 to supply a new PRM. Best decision I have made on the boat maintenance.

[transmitterdan]

The transmission oil cools things quite a lot.

Look closely at the shaft to transmission coupling. Has the square key sheared off? When that happens a lot of screeching ensues.

[skipperpete]

Originally Posted by Patman

We have a gremlin. Twice now when I put our Catalina 380 into gear I hear a loud grinding/squeal noise and feel a vibration under my feet. It does not always happen but has happened once while leaving the dock and once while waiting for a drawbridge to open.

On the latter it actually killed my engine. I quickly dropped it out of gear and cranked the motor right up. Back in gear same thing happened. We managed to limp back to the slip under idle speed. I've messed with it in the slip putting it in and out of gear and she works fine.

Thought first it was a cutlass bearing but that will not stall my engine. Now I'm thinking the transmission.

Does anyone have any thoughts?

Consider the possibility that the coupling between the engine flywheel and the gearbox input shaft is failing, they are known to release the damper springs into the flywheel housing causing a grinding/ squealing noise similar to what you describe. Before buying a new transmission it might be worth investigating this first.

[Sailmonkey]

Originally Posted by skipperpete

Consider the possibility that the coupling between the engine flywheel and the gearbox input shaft is failing, they are known to release the damper springs into the flywheel housing causing a grinding/ squealing noise similar to what you describe. Before buying a new transmission it might be worth investigating this first.

Without a doubt this is also high on the list. And free to check if you do your own work

[granche1]

Have you made any progress in figuring out what your intermittent grinding is being caused by? I have a similar problem when i put my engine in gear after it has sat unused for a week. After the initial 5 second hellish rumble, the noise clears up and she motors along just fine.

[GordMay]

Do you have the Hurth ‘HBW’ Manual?
➥ http://www.wbryant.com/temp/hurth_manual.pdf