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Very distressed - transmission and damper plate failure


Feb 26, 2015
Wylo 11 gaff cutter
Hello Everyone, hope you are enjoying the water.

My husband and I started cruising in May last year. Just before we left we installed a M-25XPB Universal/Westerbeke engine. We understand that this engine is in many Catalina 310s. We felt that the new engine would give us greater safety and reliability. The gearbox ZF10M failed after approximately 150 hours. We went through the usual checklist - our alignment, oil, and Morse cabling - all fine.

We were in Vanuatu and paid to have a new gearbox sent to us and missed cruising around this sailing paradise. Our second gearbox failed after approximately 30 hours on the way to Kiribati. We bypassed Kiribati and went straight for the Marshall Islands. Back and fourth, incorrect parts were sent to us and trouble shooting - we have now been in Majuro, Marshall Islands for 3 months and still not yet mobile. Engine troubles have now dominated our time cruising. When we took off the damper plate (R&D 22B4) we found an amazing amount of wear with the teeth on the damper 50% worn away.

We were wondering if anyone else has had trouble with their damper plate/gearboxes? We have been told that our situation is unique and feel isolated and distressed.

Thank you,

Cate and David
Jan 22, 2008
Oday 35 and Mariner 2+2 Alexandria, VA
Damper plates are wear items, and as such I swear they fail in groups. But there is always a chance that you received a substandard part. Perhaps even the spline on the transmission input shaft is suspect? Am I correct in assuming that the engine and gear box were new (and if not, how many hours were on the engine and gear box that you installed)? Is there any chance of damage to the prop shaft? What specific parts in the gear box are failing? Lastly, what condition is the transmission fluid when you have had these failures? Is it picking up particles or turning dark? Please give what specifics that you can.
Jan 4, 2006
Hunter 310 West Vancouver, B.C.
We went through the usual checklist - our alignment, oil and morse cabling - all fine.d
My condolences on your problems.

I have to ask, "did you do the alignment and other work yourself or have it done ? Unless you had defective components, I would guess that a very poor alignment (angular) was the culprit.

With your present location, I would strongly suggest you do all of the work yourself if possible. If you look through this site, you may find the necessary manuals to do the work.
Sep 29, 2008
Catalina 310 #185 Quantico
Check the 310 Forum on this site

Many of us have had problems with out damper plates. The best overall solution is to switch to a Sachs damper plate and get rid of the R&D one. It is a simple enough job that many of us have done the job ourselves at the dock.

Just search the 310 forum with the key words "damper plate sachs R&D"
Dec 31, 2012
Catalina 28 mkll #649 Port Charlotte, fl
Sorry for your bad luck.... I have the M 25 xpb universal in my boat... it has the Hurth HBW 50 trans which is pretty light..... i had the tranny rebuilt last year and there was some wear showing on the internal syncros but not any on the damper plate.... but still replaced also..... i know with my tranny we are supposed to sail with the tranny in reverse or neutral but not in forward gear or it will cause problems with the damper plate and or tranny. Best of luck, brian
Nov 18, 2009
Santana 2023C Matquette Mi

Spline wear comes "chucking" the back and forth motion in the crankshaft from the power pulses of the cylinders firing. The springs and rubbers in the plate are supposed to help dampen this out. BE SURE to use a good grade spline grease and not assemble this dry. Also low rpm operation exaggerates this wear. Be sure your not over propped and lugging the motor. I'd for sure upgrade the plate as recommended by other users. Also BE SURE the alignment pins between the engine and transmission are all there and in good shape. This is a common failure point at higher hours. Sometimes the plates crack and fail also.As for the transmission failure at low hours, someone GOOD will need to determine the failure point as to if it was part quality, lack of or improper lubrication, assembly error or installation error.
Better Luck!
Feb 6, 1998
Canadian Sailcraft 36T Casco Bay, ME
What do you do with your gear when under sail?

As for the damper the R&D plate seems to have a fairly high failure rate. A bunch of images of R&D damper spline wear are out there. Also if your idle is too low this WILL exacerbate damper plate wear and excess idling can also shorten life.
Nov 18, 2010
Catalina 310 Hingham, MA

Just so I am clear, on these engines when the idle is too slow mine shakes something awful. I presume this is what you are referring too. I typically run mine around 900-1000 RPM because that is where it flattens out and runs smooth.


Jun 4, 2010
Catalina Capri 22 Cincinnati
I have been in the "Diesel Engine/Equipment" business for over 45 years and know that there is alway a reason that caused the failure, either a defective part or installation. Of course there are made designs.The trick is to connect the Dots that will lead to the true cause. The "Root Cause," of the failure MUST be found or the failure will repeat. Unfortunately, I don't know enough facts to help you much without pictures and a complete failure analysis. I am would like to know more about the "worn teeth" on the Flex Plate that you mentioned. I believe your motor uses an Adapter Plate, between the engine's Bellhousing and the Transmission, this must be precisely centered or transmission problems will develop. Good luck


Feb 26, 2015
Wylo 11 gaff cutter
Hi All, thanks for your replies.

The engine was installed new last year, and has only minimal hours on it. It is nearly five months now since our first failure, and four since our second, so we haven't put much work on it yet.

The alignment is good on the coupling, I have checked it many times, hoping to find an obvious problem. I have not stripped down the transmissions, as they are under warranty. Westerbeke assessed the first one, but will not share their findings with us. The oil was thick and dark, so I assume the clutch cone has disintegrated. There is no power at all in forward, the shaft spins slowly but does not increase in RPM when the throttle is increased. Reverse works as normal. I have had a dial indicator on the flywheel, which is true.

We always sail with the transmission in reverse, to stop the shaft spinning. This is per the manual.

The teeth in the damper are worn in a manner similar to many images I have seen on this forum. I am having trouble attaching images.

Westerbeke have said that this failure has sometimes occurred when Repowering, but that they do not see this failure in production boats. They named Catalina specifically as having no such problems. The inference is that it is our boat which is causing the problems. The experiences I read about on this forum suggest this may not be the case.

Westerbeke are sending a new damper, make unknown, to replace the R&D. They have supplied a rebuilt ZF10M. They have stressed the importance of setting the idle above 1000rpm.

It does remain that for 5 of the 9 months we have had this engine, it has not worked. Our cruising plans are completely dashed by this, but we can hardly move on to other things while we're stuck waiting for parts. Certainly not the experience we worked for so many years for.

Jun 11, 2011
Hunter 41 Lewes
David I'm sure this is not the trip you planned but it could be worse for sure. I have dealt with manufacturers that won't give you the time of day once you have purchased their product. I could name two off the top of my head. At least Westerbeke is talking to you and sending warranty items. I hope you're having nice weather and plenty of rum.
Last edited:
Sep 29, 2008
Catalina 310 #185 Quantico
Here is what they look like

... I am would like to know more about the "worn teeth" on the Flex Plate that you mentioned. ...
1-2. First two pictures are of my old damper plate on and off the transmission. Note how the teeth are "pointy" and a bit small - not good.
3. Third picture is a picture looking into the bell housing where the damper plate mounts. You CAN remove and re-install the damper plate without removing the bell housing (been there, did that!). With a new damper plate and full teeth, you will need to elevate the engine slightly as you will need an exact alignment to re-attach the transmission. :D
4. Finally a drawing of the transmission.


Jan 22, 2008
Catalina 310 #147 Oakville Yacht Squadron
Westerbeke have said that this failure has sometimes occurred when Repowering, but that they do not see this failure in production boats. They named Catalina specifically as having no such problems. The inference is that it is our boat which is causing the problems. The experiences I read about on this forum suggest this may not be the case. Cheers, David.
Westerbeke either have their head in the sand or are on cheap drugs... They may be correct in terms of time to failure falling within warranty, but mine failed at 625 hrs; an abysmal performance when I have friends with many thousands of hours on Yanmars, Atomic 4's and others.
My transmission stopped driving forward but still operates in reverse as yours does. ATF was dark but didn't smell burned. Plates weren't burnt either. Having it apart now there is no apparent wear nor broken parts so it's back to the local distributor for ideas.
Good luck
C310 #147
Jun 11, 2011
Hunter 41 Lewes
1-2. First two pictures are of my old damper plate on and off the transmission. Note how the teeth are "pointy" and a bit small - not good.
My gut reaction is wrong metal for the hub splines. Water is a pretty soft medium when your considering drive mechanics. It can move out of the way, there can be slippage. It's not like the hard coupling of a car to the road or a bull dozer to it's tread. Was there play in the shaft to hub when you put it on?
Sep 17, 2012
Morgan 383 Fairhaven, NY
trans woes

No direct experience with the engine trans combo. But I agree that the splines must be greased - use as heavy/thick extreme pressure grease as you can find.

What kind of oil are you using in the trans? My Hurth 150 gets Mobil one SYN ATF.

Increase airflow around the trans to enhance cooling if possible

Adjust the valves on your engine to specs. Get the intakes all to the same spec and exhaust to same spec. Just to be clear: if your intake says .005" to .007" set them all at .006". I'm not saying set I & E at the same spec. I am saying make all the intake the same, make all exh. the same. Check your injector timing if possible. These steps make the engine run as smooth as possible. If you're not confident find a real mechanic if you can,

Your shift lever should, (with no cable on) engage a detent in forward or "notch" into place. The shift cable when in forward position at helm, should slip in place on the trans lever. The lever throw can't be short, as if its pulling the lever out of gear toward neutral. Adjust cable as needed.

You said you have a dial gauge. Have you checked prop shaft runout on centers (out of boat? How about with prop spinning/engine running?

Repeated failures are sometimes caused by overlooking the basics,. Assume nothing - check everything. Good luck!


Jul 31, 2014
Hunter 356 Huis Ten Bosch Marina, Sasebo, Japan
When they replaced the engine when did they do the shaft alignment? A shaft alignment can be done in the cradle but it is not complete. The boat should be in the water at least 24 hours and then a final shaft alignment check should be done. Waterborne the stresses on the hull are different than when in the cradle and will affect alignment. One other thing I can suggest is shaft thrust. I would suggest you check that too.
Oct 3, 2006
Hunter 23 Philadelphia
Is it possible that the gear shift linkage is only partially engaging? Alignment aside, that's about the only way I can imagine the "boat" being the problem.