velvet drive issue

[topseaturvy]

Suddenly my starboard transmission is making lots of noise. It sounds exactly like a bunch of gravel in a cement mixer. Not a patterned steady sound but rather very random, but constant and very loud when listening to it in the engine room. At times it sort of gets quieter for a few seconds. But I'm not sure if the noise is coming from the forward part, or in the reduction gear part of it. I don't have the knowledge to diagnose it or rebuild it. But I think I can figure out how to remove it. I'm assuming I would support the back of the engine by blocking it up from the fibreglass crossmember just forward of the transmission. On my configuration the rear mounts are attached to the transmission. I'll take lots of pictures while disconnecting everything, and then slide the driveshaft back just enough to pull it out. I'm getting a little long in the tooth and my biceps aren't exactly bulging like they were 60 years ago. Not to mention a bad back. So it might be a bit too heavy and there isn't a lot of room in there to lift it up and get it out of the engine room. No place to really configure a tripod to rig up a chain hoist either. Perhaps I getting in over my head even at that point. Rather than trying to save a few hours of a qualified marine mechanic time, (ka-ching! ka-ching!) perhaps I should just let one of those guys deal with it, start to finish?
The noise started when I had the boat hauled out to change my anodes recently. So I only went from my slip to the haul out ramp and then back again. Total run time is about maybe 20 minutes. Almost half that time it was in reverse. The noise is the same in both forward and reverse. By the way, the fluid looks fine and doesn't smell burnt.
It is a Borg Warner Velvet drive transmission model number 1018-012, Ratio 2.91:1, Serial number 3717, with just about 2000 hours on it. The engine is a Crusader 350 ( 454 ci) and the boat is a 1985 Trojan37.

At this point I'm just looking for experienced advise and hopefully parts won't be hard to track down, once the problem is diagnosed.

[mrrudely]

You can probably do it yourself and I get the money part, but If you're asking for an opinion,
let the mechanic do it.
Save yourself the aggravation and do the easier stuff yourself.

rr

[prowlersfish]

Trojan 37? Do you mean an 11-meter? Yes, the back of the engine has to be supported. The trans will weigh about 150+ pounds. Whether you can or should do it yourself or is a decision only you can make, I have no clue what your abilities are. Paying a pro to diagnose it is not a bad idea. Any chance you got something in the prop moving it around?

[topseaturvy]

Trojan 37? Do you mean an 11-meter? Yes, the back of the engine has to be supported. The trans will weigh about 150+ pounds. Whether you can or should do it yourself or is a decision only you can make, I have no clue what your abilities are. Paying a pro to diagnose it is not a bad idea. Any chance you got something in the prop moving it around?

Yes, that's right, 11 meter. I'm confident that I have the ability. I removed my heat exchangers on both engines and cleaned them out and reinstalled them a few years back. They were awkward and heavy enough. What I'm not sure about is any specific procedure when reinstalling the velvet drive like lining it up or gaskets needed etc.
The other issue is a reliable and economical parts supplier in BC Canada.

While I had the boat out to replace the anodes, I gave the prop a spin and everything felt fine. I even thought that the brass half piece that's pressed up against the driveshaft, that bonds the anodes on the driveshaft to the rest of them, had got out of alignment and was banging on something. But that's when I was up on the bridge. Once I got in the engine room, I knew it wasn't that. It's actually so loud it's difficult to tell exactly where in the Velvet drive that the noise is coming from. I do have a stethoscope tool, but I'm leery of running the trans anymore. It's probably best to have a marine mechanic hear it. I used my phone to record the sound. That might be enough for the mechanic to tell what it is. Especially if they have worked on this vintage of velvet drives before.

[topseaturvy]

You can probably do it yourself and I get the money part, but If you're asking for an opinion,
let the mechanic do it.
Save yourself the aggravation and do the easier stuff yourself.

rr

You're probably right. I pretty much do everything myself mechanically on the boat. But then again, I'm not a trained marine mechanic. A number of years ago I installed a bow thruster on the boat. Let me tell you that was a really nervous time drilling that hole in the bottom of the hull. But all went well and it sure makes a difference backing into my slip with only a couple feet clearance on both sides on a windy day.

I'm not sure how the trans case is configured inside, but I thought I might pull out the dipstick, and lower one of those collapsible arm type magnets in there, to see if it will bring out any broken teeth.

[mrrudely]

bow thruster?
now i'm jealous!

all kidding aside it won't matter how much looking you do
the tranny is coming out and getting rebuilt

[topseaturvy]

bow thruster?
now i'm jealous!

all kidding aside it won't matter how much looking you do
the tranny is coming out and getting rebuilt

Ain't that the truth. Skitter skatter, it's time to get at er.

[Big D]

Many a mechanic have been fooled into thinking that noise coming from behind the engine is always a tranny issue. You'd be amazed how sound bounces around the engine bay leading you to believe it's coming from a place that's not actually the source. Unless there's an obvious indication of a tranny problem like black/burnt oil, stuck in gear or non engagement, etc., don't condemn the tranny until you've ruled out other things like an engine issue. An engine not firing on all cylinders or just running poorly for example will cause the tranny to chatter due to an imbalanced rotation. It could also be broken springs in the damper plate. A muffler in close proximity with a broken baffle inside can be deceiving too as that usually results in a loud chatter as well. Would hate to see you go through all the work and expense only to find out the issue still exists after you replace the tranny.

[mrrudely]

does the noise go away in neutral?

[prowlersfish]

Many a mechanic have been fooled into thinking that noise coming from behind the engine is always a tranny issue. You'd be amazed how sound bounces around the engine bay leading you to believe it's coming from a place that's not actually the source. Unless there's an obvious indication of a tranny problem like black/burnt oil, stuck in gear or non engagement, etc., don't condemn the tranny until you've ruled out other things like an engine issue. An engine not firing on all cylinders or just running poorly for example will cause the tranny to chatter due to an imbalanced rotation. It could also be broken springs in the damper plate. A muffler in close proximity with a broken baffle inside can be deceiving too as that usually results in a loud chatter as well. Would hate to see you go through all the work and expense only to find out the issue still exists after you replace the tranny.

Very good info above. Does it go away when you raise rpm? Neutral?

[topseaturvy]

Many a mechanic have been fooled into thinking that noise coming from behind the engine is always a tranny issue. You'd be amazed how sound bounces around the engine bay leading you to believe it's coming from a place that's not actually the source. Unless there's an obvious indication of a tranny problem like black/burnt oil, stuck in gear or non engagement, etc., don't condemn the tranny until you've ruled out other things like an engine issue. An engine not firing on all cylinders or just running poorly for example will cause the tranny to chatter due to an imbalanced rotation. It could also be broken springs in the damper plate. A muffler in close proximity with a broken baffle inside can be deceiving too as that usually results in a loud chatter as well. Would hate to see you go through all the work and expense only to find out the issue still exists after you replace the tranny.

Thanks for that suggestion and yes, I haven't ruled out the damper plate. But to get at it I have to remove the fluid drive anyways. I've spent the last couple days building a gantry.

[topseaturvy]

does the noise go away in neutral?

No noise until I engage in forward or reverse.

[prowlersfish]

does the noise go away in neutral?

No noise until I engage in forward or reverse.

Does it go away when you raise the rpm?

[topseaturvy]

does the noise go away in neutral?

No noise until I engage in forward or reverse.

Does it go away when you raise the rpm?

I didn't try that. I didn't want to do any further damage. Especially if it meant being towed back to my marina. So the boat hasn't left the slip since I heard the noise. I have tried a couple times since while tied up to the dock, to try and pin point the noise, but only running at around 800 rpm in forward and reverse.
Are you suggesting that if the noise goes away or gets softer that that would indicate that it might be the damper plate? What rpm are you suggesting?

[prowlersfish]

If the noise goes away when you raise the rpm, the cause could be a misfire or the dampener plate or both. They will aggravate each other. Even a slight miss can cause a noise. I have fixed many a transition noise issue with a carburetor adjustment.

Maybe 1000-1200 rpm?

As far as getting towed back to the marina, you have 2 engines and a bow thruster so...... But that's your call, not mine.