Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-10-2021, 07:41 AM   #1
Veteran Member
 
City: Oyster Bay
Join Date: Dec 2020
Posts: 62
Transmission rattle

On my Mainship 34 trawler twin 4lhastp one transmission is making a rattling( what I call death noise) when in gear at idle once I give it a few hundred rpm’s more it goes away and is quiet. Mechanic believes there is a sacrificial plate between engine and transmission that could be failing. Is anyone familiar with this ?
Roger L is offline   Reply With Quote
Old 11-10-2021, 08:02 AM   #2
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Join Date: Oct 2007
Posts: 16,565
Greetings,
Mr. RL. Damper plate, perhaps? If so, a maintenance item.
__________________
RTF
RT Firefly is offline   Reply With Quote
Old 11-10-2021, 08:48 AM   #3
Guru
 
tiltrider1's Avatar
 
City: Seattle
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 4,308
My experience says it is not the dampener plate. My guess is we are talking about a velvet drive transmission. I have seen this issue in velvet drive transmissions. Maybe some one can confirm transmissions type.
tiltrider1 is online now   Reply With Quote
Old 11-10-2021, 09:34 AM   #4
Guru
 
catalinajack's Avatar
 
City: Edgewater, MD
Vessel Name: Catalina Jack
Vessel Model: Defever 44
Join Date: Nov 2011
Posts: 3,585
Quote:
Originally Posted by tiltrider1 View Post
My experience says it is not the dampener plate. My guess is we are talking about a velvet drive transmission. I have seen this issue in velvet drive transmissions. Maybe some one can confirm transmissions type.
Yes, it's the damper plate springs becoming worn and loose in their mounts. When RPM is increased the springs compress and the rattling stops. Eventually one or more of those springs will break and drop down to the bottom of the bell housing where they have been known to stop an engine dead. Replace the damper plate soon. By the way, there is no such thing as a "sacrificial" plate. The damper plate is not part of the transmission. It is bolted to the engine flywheel and is synonomous with a pressure plate on vehicles with manual clutches.
catalinajack is offline   Reply With Quote
Old 11-10-2021, 11:03 AM   #5
Guru
 
City: Anacortes
Join Date: Nov 2012
Posts: 1,189
A failed damper plate is extremely common and produces precisely these symptoms. I’m not familiar with other issues with Velvet Drive, though I’ve owned a few, but even so those issues would be far less common than a failing damper plate.

Start there.
ghost is offline   Reply With Quote
Old 11-10-2021, 11:06 AM   #6
Guru
 
City: Boston
Vessel Name: Adelante
Vessel Model: IG 30
Join Date: Nov 2016
Posts: 1,609
Quote:
Originally Posted by tiltrider1 View Post
My experience says it is not the dampener plate. My guess is we are talking about a velvet drive transmission. I have seen this issue in velvet drive transmissions. Maybe some one can confirm transmissions type.
Yanmar 4LH engines are probably matched with ZF transmissions. Very unlikely to have older velvet drives. Yanmar damper plate goes for about $500 ea. I believe they are polyurethane so may not have springs. Investigation of noise location should be done with mechanics stethoscope.
SoWhat is offline   Reply With Quote
Old 11-10-2021, 12:59 PM   #7
Guru
 
porman's Avatar
 
City: Duvall, Wa. USA
Vessel Name: Beach Music II
Vessel Model: 2003 Mainship 430 Trawler
Join Date: Aug 2014
Posts: 1,040
Our Mainship has ZF transmissions. In order to make the props counter rotating one transmission is in forward and the other is in reverse when moving forward. At idle speed and moving forward the transmission in reverse rattles. Goes away with a slight load. At idle speed and moving in reverse the other transmission rattles, as it is now in reverse. After some research I've decided it is the design of the transmission causing the noise. It has been rattling since we bought the boat 7 years and 1400 hours ago so I think if it was a damper plate it would have broken a long time ago. As an aside, I just found out that the Z in ZF stands for Zeppelin, the company that made dirigibles.
porman is offline   Reply With Quote
Old 11-10-2021, 02:09 PM   #8
Guru
 
AusCan's Avatar
 
City: Adelaide
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 3,218
You can buy a bushing kit for the polyurethane type damper plates for about $50. Easy to replace on the Centa brand damper plates.

Pulling the transmission can be a pain in the butt. Before you start, pick up a couple 4" long bolts the same diameter & thread as the bolts holding the gearbox onto the bellhousing. Cut off the heads and screw them in by hand. Use them to guide the gearbox shaft into the damper plate splines.
AusCan is offline   Reply With Quote
Old 11-10-2021, 02:38 PM   #9
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
I agree w RT.
Edit, and AusCan

But once I had a very noisy (rattle like) gearbox .. (Kanzaki). It was aluminum and seemed to amplify the noise.
I installed a pricy gear oil pump and plumbed it (in and out) to the gearbox. I then mixed motorcycle synthetic racing oil w 85/140 automotive gear oil and one other thing I can’t remember. All to get the viscosity up.
That fixed the noisy gearbox noise and no other changes were noticed.

I’m quite sure the gear teeth in the trans were whack’in back and forth from the three cylinder engine’s torsional vibration (Yanmar).
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 11-10-2021, 03:34 PM   #10
Guru
 
City: Boston
Vessel Name: Adelante
Vessel Model: IG 30
Join Date: Nov 2016
Posts: 1,609
Quote:
Originally Posted by AusCan View Post
Pulling the transmission can be a pain in the butt. Before you start, pick up a couple 4" long bolts the same diameter & thread as the bolts holding the gearbox onto the bellhousing. Cut off the heads and screw them in by hand. Use them to guide the gearbox shaft into the damper plate splines.
McMaster sells double ended studs. I leave them in.
SoWhat is offline   Reply With Quote
Old 11-10-2021, 04:23 PM   #11
Arc
Guru
 
City: Long island
Vessel Model: Eastern
Join Date: Aug 2018
Posts: 633
Change the oil . I had ZF’s do this. I ran them on #46 hydraulic oil and 30# motor oil 50/50. Solved the problem .
Arc is offline   Reply With Quote
Old 11-10-2021, 04:26 PM   #12
Guru
 
AusCan's Avatar
 
City: Adelaide
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 3,218
Quote:
Originally Posted by Nomad Willy View Post
I agree w RT.
Edit, and AusCan

But once I had a very noisy (rattle like) gearbox .. (Kanzaki). It was aluminum and seemed to amplify the noise.
I installed a pricy gear oil pump and plumbed it (in and out) to the gearbox. I then mixed motorcycle synthetic racing oil w 85/140 automotive gear oil and one other thing I can’t remember. All to get the viscosity up.
That fixed the noisy gearbox noise and no other changes were noticed.

I’m quite sure the gear teeth in the trans were whack’in back and forth from the three cylinder engine’s torsional vibration (Yanmar).
The noise often is from the gearbox, but but a good damper plate can reduce or eliminate the rattle. Mine does until the bushes wear out. I'm still searching for the the root cause of the problem.
AusCan is offline   Reply With Quote
Old 11-10-2021, 05:43 PM   #13
Arc
Guru
 
City: Long island
Vessel Model: Eastern
Join Date: Aug 2018
Posts: 633
If it’s a straight cut gear transmission they can rattle. A lot has to do with the prop. At low speed the hull can make the blades cavitation. This causes what would be normal Load to disappear for a split second . This lets the prop speed up . When that happens the gear flips from one side to the other causing a rattle. Think of a harmonic wave. The minute you speed up the engine load overcomes any slippage and the rattle goes away. This is also very common with twin engine boats that run a transmission in reverse . The ratios are often slightly different and it unloads one prop. Usually just a few hundred RPM makes it go away.
Arc is offline   Reply With Quote
Old 11-10-2021, 08:49 PM   #14
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
Quote:
Originally Posted by AusCan View Post
The noise often is from the gearbox, but but a good damper plate can reduce or eliminate the rattle. Mine does until the bushes wear out. I'm still searching for the the root cause of the problem.
AusCan,
Looks like my damper plate was OK since the increased lube oil viscosity solved the problem completely.
Did’nt think of the damper plate then. But I can see how it likely would have solved the problem also.

FYI the syn oil I used was two stroke racing oil that wouldn’t work in two stroke oil injected engines .. not recommended by the manufacturer. Viscosity too high. Very high viscosity retention at high temperatures. Hard to mix and doesn't stay mixed for long periods.

I think the semi-transparent multi-colored damper elements used in place of the usual springs or plastic wedges have the best dampening absorption rates and should be the most effective. But since they don’t seem to be the most widely used there may be a downside like don’t last as long …. but I don’t know.

I’d like others to follow up on this and deliver better and more recent information. Springs in damper plates probably are susceptible to variations in dynamic rotational mass and rpm in addition to other things that are involved. In short it appears to me that most damper plates ideally should be designed for only one engine. Food for thought .. or/and conversation.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 11-11-2021, 04:57 AM   #15
Guru
 
Cigatoo's Avatar
 
City: Narragansett Bay
Vessel Model: Grand Banks 36 Classic #715
Join Date: Sep 2016
Posts: 1,857
Quote:
Originally Posted by Roger L View Post
On my Mainship 34 trawler twin 4lhastp one transmission is making a rattling( what I call death noise) when in gear at idle once I give it a few hundred rpm’s more it goes away and is quiet. Mechanic believes there is a sacrificial plate between engine and transmission that could be failing. Is anyone familiar with this ?
You didn’t say what type of transmission you have. 4LH Yanmars can have a Kanzaki transmission that is a gear driven (vs hydraulic) transmission. A rattle at low idle is somewhat normal. If it is a Kanzaki change the gear oil every year. Use same oil as in engine.
__________________
Carl
Cigatoo is offline   Reply With Quote
Old 11-11-2021, 05:44 AM   #16
Veteran Member
 
City: Oyster Bay
Join Date: Dec 2020
Posts: 62
Thanks for the counter rotating info but the port transmission is quiet in forward and reverse.
Roger L is offline   Reply With Quote
Old 11-11-2021, 05:47 AM   #17
Veteran Member
 
City: Oyster Bay
Join Date: Dec 2020
Posts: 62
I’m hoping this is the correct diagnosis as the mechanic suspects, not a major repair.
Roger L is offline   Reply With Quote
Old 11-11-2021, 06:23 AM   #18
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Join Date: Oct 2007
Posts: 16,565
Greetings,
Mr. RL. I've never done it but I understand changing a damper plate is NOT considered a major repair.



I could be way off here but...I'm not sure about your "mechanic". "Mechanic believes there is a sacrificial plate..." Perhaps you should hire someone more familiar with the technology of marine machinery.
__________________
RTF
RT Firefly is offline   Reply With Quote
Old 11-12-2021, 01:54 AM   #19
Guru
 
catalinajack's Avatar
 
City: Edgewater, MD
Vessel Name: Catalina Jack
Vessel Model: Defever 44
Join Date: Nov 2011
Posts: 3,585
Quote:
Originally Posted by RT Firefly View Post
Greetings,
Mr. RL. I've never done it but I understand changing a damper plate is NOT considered a major repair.



I could be way off here but...I'm not sure about your "mechanic". "Mechanic believes there is a sacrificial plate..." Perhaps you should hire someone more familiar with the technology of marine machinery.
Yes, removing the damper plate, eight bolts more or less, and replacing it with new is not a big deal. Plates cost less than $200 or so. It is a big deal to remove the transmission or even just sliding it back on threaded bolts. It requires decoupling the prop shaft and sliding it backwards through the stuffing box which sometimes can be difficult in itself. So, not a major repair?
catalinajack is offline   Reply With Quote
Old 11-12-2021, 02:20 AM   #20
Moderator Emeritus
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 21,187
I replaced the damper plates in our last boat. It was easy BUT I had the engines and transmissions out of the engine room at the time so it was easy to slide the transmission back from the engine. If the engine and transmission are installed in the boat it may range from easy to a real PITA depending on how the boat is configured.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
Comodave is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 03:47 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012