1999 Crusader 502 velvet drive. 440 hours. I have noticed a kind of clattering noise in the starboard transmission. No leaks. Plenty fluid. Just happens at low rpm. Mainly during warmup. Just an occasional sound. Transmission shifts and runs great. Any ideas.
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Velvet drive clatter
- Thread starter MarkMuck
- Start date
- Joined
- Feb 3, 2006
- RO Number
- 20150
- Messages
- 372
Do you have shaft zincs? Sometimes get loose and rattle on the shaft and sound travels up. Think positively simple first.
We have 'em and one has chattered at low RPM since we've had it - about 8 years. No problems with it. It worried me when we first got the boat and I was told then it was normal. Guess it is. For the record though i am not a mechanic.
Keith
Keith
This is common as engine power strokes cause gear lash to clatter especially when you have an inline 6 diesel or a V-8 that has a very low idle or has a rumble or miss near the bottom rpm's. This should clear up completely by 900 or so rpm's or just higher with an inline 6 or a hundred or so rpm's lower with a V-8. Somewhere around here I have a few TSB's on this and that it is 'normal' at the lowest rpm's.
Hope this helps
Hope this helps
It's common... but not "normal" .
VD says to avoid letting it clatter as it can be damaging to the drive. Usually a good thorough tune-up to optimize smoothness will eliminate the clatter , or sometimes just re-adjusting the idle speed setting to spec (maybe 700-750 in F gear when warm?)
[However, injected engines' ECM's will normally control idle rpm (~650 in F).]
VD says to avoid letting it clatter as it can be damaging to the drive. Usually a good thorough tune-up to optimize smoothness will eliminate the clatter , or sometimes just re-adjusting the idle speed setting to spec (maybe 700-750 in F gear when warm?)
[However, injected engines' ECM's will normally control idle rpm (~650 in F).]
- Joined
- Jun 23, 2002
- RO Number
- 9099
- Messages
- 1,089
Cause is springs rattling in the damper plate due to clearamce wear. This plate is between engine and transmission. Condition is harmless and not uncommon.
MarkMuck,
On the good engine, start it and then pull off one of the spark plug wires. Does that engine make the same noise? If yes, then the starboard engine may have a bad plug, bad wire, or bad cylinder or two. A compression test may be a good idea if plug/wire inspection looks OK.
On the good engine, start it and then pull off one of the spark plug wires. Does that engine make the same noise? If yes, then the starboard engine may have a bad plug, bad wire, or bad cylinder or two. A compression test may be a good idea if plug/wire inspection looks OK.
You either have a bad drive plate, or your engine is running rough. Most likely a bad drive plate.
The drive plate is there to absorb the uneven torque of the engine at idle.
They are there for a reason and very common to wear out. Yes, you want to have it fixed.
The drive plate is there to absorb the uneven torque of the engine at idle.
They are there for a reason and very common to wear out. Yes, you want to have it fixed.
Ghost is correct on your two possibilities. The symptoms of a bad flex plate or a misfiring engine are identical. When I had my boat surveyed, diagnosis was bad clutch plate on one engine. I tuned it up the first week I had it and one of the plug wires was bad at the cap. That was 400 hours ago and I've never heard it again.
There is a legendary post of a guy who removed his VD something like 4-5 times with multiple rebuilds, new damper plate etc. This went on for over a year and the problem turned out to be a bad wire or cap.
Bob
There is a legendary post of a guy who removed his VD something like 4-5 times with multiple rebuilds, new damper plate etc. This went on for over a year and the problem turned out to be a bad wire or cap.
Bob
This noise is common on almost every velvet drive I have seen including mine which are 18 years old. The noise in mine sounds like marbles at idle and have been there since boat was new. Mine are also connected to crusader 502's. I would not lose any sleep over this especially since you are not having any issues
My present Velvet Drive 72C's connected to 5.7L MPI's don't ever clatter, but they engines are well-tuned and idle speed is completely controlled by the ECM.
My old VD 71c's on the old 5.7 carbed would clatter at low idle in gear occasionally, but that always disappeared after a tune up and resetting up to spec carb idle-rpm-in-gear correction.
My old VD 71c's on the old 5.7 carbed would clatter at low idle in gear occasionally, but that always disappeared after a tune up and resetting up to spec carb idle-rpm-in-gear correction.