V drive rattle at low RPM

[carlorw]

I purchased a 33′ Wellcraft Express Cruiser with twin 8.1 liters Volvo Penta engines and V drive transmissions. Unfortunately, I trusted the seller as to it’s condition. I purchased the boat which was half way across the country through a reputable broker and a technician that I hired who was not very reputable. I had the boat shipped to me and when I received the boat, the starboard engine didn’t run well and the Starboard transmission was make a load banging sound when it was put into gear. I hired a local marina to diagnose the problem. They remove the fluid filter from the starboard transmission and it was full of metal fillings. We decided to pull the engine and replace the transmission rather than tear it apart and rebuild it. There were no rebuild transmission available within a reasonable time and distance. I found a used transmission at a nearby boat engine rebuilders. He had no record as to where it came from, but it was in very good condition and he ran it up on their test bench and everything looked good. I purchase the transmission and had my marina install it. I received a 6 month warrantee from the supplier. When we put it in the water for the sea trial, there was a gear rattle at lower RPM which is not there on the Port engine. The supplier is saying that some V drives are like that and it may be nothing to worry about. I am concerned and looking for anyone’s thoughts or experiences. I have included a video link of the V drive noise.

https://onedrive.live.com/?authkey=%21Ailj%5FxwtHPAR7t4&cid=9EE4302B135B6869&id=9EE4302B135B6869%215379&parId=root&o=OneUp

Thanks

Carlo

Topic

[Dan]

I have a friend with ZF63IV transmissions hooked up to 5.7 crusader engines,one started making this noise (bad) at around 700 hours.

He has tried (without success) changing the oil to Delo 40,removed the gearbox and had it torn apart (there was nothing wrong with it) reinstalled with a new torsional coupling.

Check your plugs/cap/wires, if there is the slightest miss in the engine at idle it will enhance the rattling noise, in the end the only thing that really worked was bumping the idle speed up 50 -80 rpm’s via the stop on the morse controls.

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Tony Athens

[Tony Athens]

Although you did not specify it, 99+ % you have a ZF63IV transmission. This is a good gear overall but is very susceptible to “gear rattle” at low RPM’s, and it seems especially so with gas engines.. Not sure why “gas engines” but it’s probably related to a NOT properly matched torsional coupling of or the one you has lost much it its “Damping Qualities”.. You replaced the with a used gear.. Did you replace the torsional couplings? Take any pics of it so I can ID the type?

As to potential damage– if the noise (like ball bearing flying around inside the gear)– other than being very annoying, not a lot to worry about if it goes away if you raise the RPM 50-100 RPM.. Switch the oil to an HD 15W-40 oil like Delo 400 or Rotella T..

Tony

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[Author]

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