Need some Velvet drive help.

[yorklyn]

Here is a short video of my newly rebuilt port velvet drive 1:52. It didnt sound quite right when I first idled the boat to the gas dock for fuel. originally thought it could be an alignment issue so the next morning I checked the alignment and it was very close. the rotation is correct. I decided to run the engine with the tranny in gear, the video shows the sound. I did decide to to run her later in the day as I was going to completely "lose it" if i was not able to try her out. I ran her about 2 miles at 3500 rpm and didnt have any noticeable vibration. Its not on the video but when I brought the rpms up to 2000 with the shaft disconnected the noise didnt seem to get worse.
Could this be the flex plate between the engine and tranny (which is also brand new)??? I REALLY am getting sick of pulling out and putting back engines!
Any Ideas?????
https://youtu.be/xlE-H8NQnhk

[mikeandanne]

Todd your boat looks great ,nice job......google velvet drive rattling/noise....there is a ton of info about it,seems fairly common, maybe not as bad as you think....Mike

[yorklyn]

Mike,
You just made my day!! Never even thought to google that issue! just read a bunch of sites where my exact issue was described to a "T". My idle is set low , 500-600, didnt get into the fine tuning yet. Will be bumping up the rpms before this weekend.
Thank You!

[prowlersfish]

Whats it sound like with the shaft hooked up , and at speed ?

[yorklyn]

sounds the same with the shaft hooked up at idle and in gear. quiets down when rpms go up. still some noise at 1000 but couldnt really hear it above 1500.

[prowlersfish]

Engine running smooth ?

[yorklyn]

Very smooth. Of coarse the starboard engine looks like it may have a small oil leak at the rear main seal! Sure glad everything was working perfectly before I threw 20k into the engines and trannys, lol!

[yorklyn]

I realize I'm being optimistic thinking a higher rpm will fix that awful sound but it sounds like a lot of people had the same issue.
Who knows, maybe I'll actually get lucky for once! Probably not but there is a slight chance!

[BobCT]

Todd,

(Edit.... The first 1/2 clearly sounds like a rattle, I hear more of a squeal just towards the end).

That sounds more like a squeal than a rattle to me (anyone else agree)? When I bought my boat, the surveyor said I had a bad flex plate and it turned out to be a bad wire on the cap so it was running on 7 cylinders. That sound is identical and misdiagnosed all the time. Just for kicks, I would throw your timing light lead at the plug end of each cylinder and make sure each is firing.

If the idle is too low AND you have that issue it'll appear to go away as RPM's go up. Some people swear that all/most VD's make noise at low RPM's and is normal. Mine don't and I keep my idle a little lower than spec. By ear, close to where yours our now.

A few seasons ago, mine port trans starting making a squealing/screeching sound when I ran it w/o fluid for a few minutes. The noise eventually went away but I had to rebuild it because the clutches overheated and it was hanging up in neutral.

Can you feel it with your hand, meaning some physical contact/interference? (Like... Starter just touching edge of flywheel?).....

[prowlersfish]

The reason I asked the questions , many times a flex plate noise will go away with load and a little rpm . The same goes with a rattle noise due to miss / rough running .

[Big D]

I agree it could just be an engine runnability issue. As described above, check that all cylinders are firing. Maybe it's a video thing but it almost seems as though there is a jitter on the flange when it's spinning. You can try bringing the coupler about 1/4" away from the flange, put a mark on top of both, like a timing mark, then stick your timing light on it while running. If it hops all over the place, you need to find the cause; likely engine related.

[yorklyn]

The engine "seems" to be running fine. When I set the Timing the timing Mark was smooth and steady. I did find out that I was quite off on the original timing during the original 20 min warm up. Had to turn the distributor almost 1/4 turn to get it set properly. Wonder if I could have fouled a plug? It seems to be idleing ok though, even at the low rpm. I've had a bad flex plate before and it sounds kind of like that but the sound seems to be coming from the flange/reduction gear area??
I do like the idea of checking plug wires with the timing light as well as checking the flange speed for smoothness with the light as well.
Will bring a mechanics stethoscope down with me next time to try to pin point the noise.
The description of the noise ,which ironically was described the exact same way by other people with this same issue , sounds like " there are spare parts that came loose rattling around in the case"
I also checked the trans oil for signs of metal shavings but didn't find any.
Thanks for the assistance everyone!

[BobCT]

Todd, there was a legendary post on the Crusader forum a couple of years ago. Guy had the exact same issue and rebuilt his trans like 2x, replaced the damper plate more than once, flywheel, starter.. Etc.
This went on for like 6 months and turned out he had 2 plug wires crossed.

Once you know all cylinders are firing, make sure it's the right cylinders. With all the work you've done, easy for you and/or rebuilder to make an easy mistake. If for some reason you need to pull the trans give me a call. You can do it in the slip...

Did the rebuilder bench test it? Kind of hard to believe a new damper went bad. I know you ran it in your shop, any hint if noise then? Did you do anything plug wire related after that first run?

Bob

[yorklyn]

Bob,
Ive been thinking about what everyone has been saying about it being the engine either missing or not firing. I had triple checked everything before firing them up in my shop but at the last minute decided to put shrink wrap #'s marking each plug wire 1-8. I could have easily screwed up the wires up at that point. that could explain why the starboard engine fired right up but the port was much more difficult and why I had to turn the distributor a 1/4 turn to dial it in so it would idle?????
the builder did not bench test engines because i didnt have the funds to have him purchase all the new accessories and install them plus i wanted to paint the engines properly.
I did make the mistake of painting the flywheel and dampeners and flanges. luckily P-dogg pointed out my mistake and i ground the paint off of the mating surfaces. the springs on the dampeners are painted but I cant imagine that being a issue.
when I started them in my shop i fired them up and ran them at 2000 rpm for 15 minutes then shut them down immediately, I woke as told not to idle them until i had the cams broke in . i ran them again in the slip at 2000 rpm for another 15 minutes before i let them idle to set the timing. in hindsight i should have put them in gear and tested the transmissions .

[LandVF36]

Todd, I listened to your video and I have to say that on my port engine, I've have a similar rattle at low RPMs when its cold. After I've ran them a little and I return to idle it goes away. I've changed the fluid a few times and never see any pieces. Over the past 8 years, I've often though about pulling that tranny and having it looked at, but an old timer around our marina told me it was normal, so I don't put it in gear with the hatches open and I rarely drive from the salon so I don't hear it. I bet I've put on 1000 hrs since I first noticed it.