Marine Transmission Rattling Noise Common Misdiagnosis Velvet Drive 5000 ZF Hurth 630 63A 68A 8.1

This is a very common misdiagnosis. An uneven running engine at idle which most generally is a cylinder misfire will resonate through the aluminum marine transmissions such as the Velvet Drive and ZF marine units. In this video I verify the concern, identify the issue and root cause. I repair the vessel.

[@garylozowski1419]

Yep …. Found one wire loose on distributor cap. Also, idle RPM was too low. Once speed was increased the rattle disappeared. Thank you Chris.

[@12000Jetlag]

When they did the survey on my 1995 41C Silverton I heard the same sound. The surveyor that did the mechanicals told me to relax and get a tune up. He was correct!

[@MadLudwig]

I had that exact noise coming from the starboard 8.1 Crusader in my Silverton 2005 34c. Changed the plugs and it went away. I also changed the exhaust elbows, risers and stainless wing plates. The elbows and wing plates are a critical maintenance item for the 8.1 engine.

[@garysnyder6020]

Can't thank you enough for this video. Changed the plugs in my 1979 PennYan and the tranny noise is now non existent. I do have an extra tranny I will bring for you to refurbish some day, Hopefully I can drop it offf when you open for the day and take it home that evening. Avoid shipping from Erie, Pa.

[@JeffNiemeier]

Similar problem with my 1999 Mercruiser 7.4 MPI and my Velvet Drive 5000! Going to hire someone with an analyzer to look for a misfire.

[@joshuaroy9672]

Any updates on that? I have the same issue but my customer won’t believe me and refuses to give me the go ahead. 😅

[@JeffNiemeier]

@@joshuaroy9672 Yes, I'm just finishing up my KZbin video for my channel. Bad injectors causing a misfire! Replaced them and engine increased 1500 rpms!

[@desiree00000pp]

Hello 88.7 4 searay borg warner vd I have that same noise but only when I pit in drive reverse I don't hear that pleas help?

[@kurtlyons136]

I had the same noise due to a carburetor problem. Idle seemed fine when listening to the engine but there was a subtle roughness the caused the rattle. Older Velvet Drive trans.

[@LakelandAutoMarine]

Yep. Cast iron transmissions can do it, too. Anything that causes a misfire or an uneven running engine will cause the transmission to rattle.

[@vintagesirvivor]

I'm missing something here??? So at idle and in neutral there is no noise, right? But once in gear, the noise is loud? How does this indicate a misfire? So in that instance or example as in the video, where does the noise sound like it is coming from?

[@larryjohnson5597]

You must’ve sold a lot of transmissions

[@benjaminishak7206]

Awesome video. Mine makes a noise like that but only in reverse at idle so I don’t think it’s a misfire ? Was this one doing it in neutral?

[@LakelandAutoMarine]

It was worse in neutral. They can do it in gear as well.

[@garylozowski1419]

Can this same noise occur on a 10-05 (72C) Velvet V-drive with a rough engine idle ?

[@LakelandAutoMarine]

Yes it can!

[@joeyscaldafari1854]

I have this exact issue with both 2006 8.1 crusaders. I can't find a real Crusader mechanic in South East Florida? If you know one please let me know.

[@LakelandAutoMarine]

Good luck. Good people in any industry are hard to find. You might want to start with a simple tune up first.

[@tacotuesday000]

Will the missfire cause the any trans issues down the line from the rough running?

[@LakelandAutoMarine]

Not normally.

[@RR-dc3nw]

Having the same issue. Was this while the boat was in gear?

[@LakelandAutoMarine]

Mostly neutral. Anything to cause an uneven running engine can cause these aluminum transmissions to rattle.