Transmission slipping

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WALSHIE

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I was running the boat today and while on plane the starboard engine slipped.

2001 Silverton 330 with 350 Crusaders and ZFHurth v-drives.

RPMs revved, lost power. I took her out of gear and checked things out. I had alot of water in bilge (weight) due to something unrelated...apparently my damn float switches don't work, who knew!!

Anyway, I went on plane and it did the same thing again, went in and out of gear as I watched it. I checked the cable linkage on both sides and compared the movement on both sides, that looks fine.

I haven't changed the fluid in the seven years I have her. The fluid level was ok and nice and pink, no burnt smell

Any chance a clogged filter would do this? No noise, no smells, no vibration.
 
By "went in and out of gear as I watched it" you do mean the tach revved , not the shift lever moved, yes?

7 years sounds rather like maintenance neglect, so perhaps the fluid has thinned to the point of not allowing sufficient pressure applied to the clutch pack or other old-fluid-related cause of the slip? Do you have a maint. schedule listed in your Hurth manual?

Foley engines says replace fluid on Hurth transmsissions at the start of each season, and at 250 hr intervals if you run that much.
I expect they deal mostly with diesel applications, though, but at lower input rpms.

http://www.foleyengines.com/resourc...rine-transmissions-ins-and-outs-basic-service .

If your Hurths have a filter or screen (my VD's don't) I would certainly check/clean those, but change that fluid. If you are lucky you might avoid a rebuild.

FWIW- The fluid in my VD 72C's gets changed each late fall layup, but I'm sure a lot of people put that off.
 
Make sure your thru hull bearing isn't going bad. Had the same symptoms on my previous boat and it turned out to be a bad thru hull bearing.
 
Try to get down there while underway and confirm what's going on. While it's hard to see with v-drives, it would be nice to confirm that the shaft isn't slipping in the flange that bolts up to the back of the v-drive. I don't have much recent Hurth experience but I remember that some use a Woodruff key on the shaft and either one or two setscrews that fit into dimples on the shaft. If the key shears off, the two setscrews will sometimes hold the shaft in place at lower speeds.

The Hurth reverse gears and v-drives are pretty beefy for most pleasure boats. Hope yours doesn't need a rebuild.

Bill
 
Bill, interesting thought!
I will verify the set screws are in place where they belong, in the dimples.
There is no key on the shaft, the coupling is machined and set in place with two set screws. Not the best setup if you ask me!
I did replace both shafts this spring but also put on at least 20 hours on boat since then and it ran flawlessly.
 
With new shafts in spring, Bill's suggestion certainly does sound like a good possibility.
 
Has to be a key. A "woodruff" key is not visible with the coupling in place. The set screws prevent fore and aft displacement, not rotational.
 
OHB, you are correct, there is a key! My bad!!!
I will check the coupling and make sure the key is in place.
 
I have not had one of those apart since 1957.
The Plates are forced together by a small Piston.
If that piston jamb's the Plates don't get the Hydraulic pressure to hold them together.

On some of them the piston moved a Cam. The Cam, when in place would be holding the plates in pressure with each other. If the Cam don't move far enough, the plates are not bonded.

Normally, unless you have a real dirty situation, you won't see Dirty or bad smelling oil if your filter is working good.

Try this first! Change the oil and filter. Have two other filters handy and more oil.
At the first change with new oil, move it in and out of both gears sort of rapidly.
That should stir up the Detritus up off the bottom of the Gear box and the Filter should catch it.

That should take you a half hour or so.
Change oil and filter again. Repeat the process. It may be OK this time.

As a Kid the old "Tex" (Boat mechanic) explained how those "Inner and outer" plates worked.
The Hyd Pump and Solenoid cams were a little bit smokey to me.

After a couple of Oil changes, I felt like jumping into Lake Washington to get that smell off me. I had a 500Cc Matchless I rode to and from work. An extra long trip home was good for Aerating the Soul on the Bike and the soul of the biker.

Info for you guys. The Smaller the body of the Reduction Gear, the shorter the lifetime between repairs.
 
NO! Don't go down there with the boat in motion! Just draw a reference line across the coupling and shaft with a Sharpie. If the line moves, your shaft is slipping. This is easier and safer.
 
I knew a guy that had a 35 ft Silverton with Hurth VDrives. The woodruff key at the front end of the prop shaft where it stuck out the front was always walking it's way out of the key way. He had to drive it back in place 2-3 times a year. Might be a good place to look.
 
quote:
Originally posted by CRay

I knew a guy that had a 35 ft Silverton with Hurth VDrives. The woodruff key at the front end of the prop shaft where it stuck out the front was always walking it's way out of the key way. He had to drive it back in place 2-3 times a year. Might be a good place to look.

Click to expand...


I wonder why he didn't figure out a number of different potential ways to block it's escape to help take the worry out? And could it have been a slightly wrong size too?
 
Thanks for the feedback guys. I double checked and the key is still there, in proper position so it's not a shaft issue.

I honestly don't think it's the transmission. I was trying to change fluid as suggested but have to drive 1/2hr to store, found out local guy retired. I'd like to find out before I haul. I'd also like to check the prop, feels like cavitation.
 
Ok, you said it went in and out of gear as you watched, but don't think it is the transmission. Besides the confusion that provides, do you feel it could be due to a bag or weed on the wheel or ignition on one or more cylinders energizing and de-energizing?
 
Yes, the shift linkage moves and changes just fine. The fluid looks great and there are no noises. I'm real curious as to what the prop looks like.

Funny you mention ignition on one of the cylinders. A fellow boater with a 4cylinder outboard said he saw the same symptoms and it was the spark plugs. Do you think I should focus on the engine too? Sounds like I should do everything in my power before pulling the transmission (complete tune up, change fluids, etc).
 
You should be able to tell if revs are decreasing from normal or increasing to normal, but if they go low again and you aren't sure , put an inductive pickup timing light on each successive spark plug wire and see if one is not firing.

How often do you do complete tuneup? Is this a carbed or injected engine? If injected , use a MEFI scanner to see if there are any codes and to try a power balance test when the issue manifests.

Yes- If there is any question as to whether you have a transmission or combustion problem by all means rule out the engine side 1st. From here, it is sounding a bit less like a transmission issue, but you are the one on the boat.
 
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