2006 Beneteau 423 - Volvo engine / prop shaft vibration

[Richard McDonald]

A sea trial, earlier this week, on a 2006 Beneteau 423 revealed a Volvo Pentax engine / prop shaft vibration. Even at a moderate 1500 rpm I could see significant visual deflection of the shaft when under way as I was inspecting the engine back side compartment. The vibration can also be felt in the cockpit and increases with significant intensity up to 2900 rpm, where I would called it severe. The obvious vibration is what pushed me and the surveyor to check further while underway with the engine.

The sea trial was done after the haul out inspection. No lateral shaft movement was felt when the propeller and shaft was inspected while on the hard before splashing back in for the sea trial.

I am several hundred miles from the boat and a subsequent inspection done by the "broker/mechanic" did not show any alignment issues between the engine and shaft coupling. He suspects a shaft and/or propeller issue.

The vessel has a 3 blade fix propeller, see attached pictures.

This is the only major issue (other then some other medium and small stuff, which are normal for a 2006, that needs to be addressed) that is holding up the purchase process until the root cause of this vibration is identified and corrected.

Any feedback on the vibration issue would be greatly appreciated, as well as, any other recommendations as to shaft and propeller choice, if it they need to be replaced.

Richard

 

[sail sfbay]

Suggest having a marine Volvo Pentax engine mechanic inspect and check the motor mounts.

 

[JamesG161]

It looks like no water flow through the Cutlass Bearing. Some sort sealant against the strut.
But that set up is new to me.

Jim...

 

[Ralph Johnstone]

It looks like no water flow through the Cutlass Bearing. Some sort sealant against the strut.

Looks like the PO didn't want it to get wet !

 

[Ralph Johnstone]

Suggest having a marine Volvo Pentax engine mechanic inspect and check the motor mounts.

I would want that as a minimum and nothing less.

Not to sure if a broker/mechanic is one individual but I can always tell when a boat broker is lying, his lips are moving .

 

[Davidasailor26]

It looks like no water flow through the Cutlass Bearing. Some sort sealant against the strut.
But that set up is new to me.

Jim...

That’s a normal Beneteau set up. What you see coming out of the skeg is a stainless shaft log. Sealant is applied where the log comes out of the skeg. The shaft goes through the log with a black rubber cutlass bearing at the very back of the log. They usually have a dripless shaft seal and a way of injecting water behind the seal. The water flows between the log and the shaft, out the grooves in the cutlass.

The fact that there was no lateral play in the shaft suggests that the cutlass is adequately lubricated, otherwise it would heat up and wear out.

I would lean toward potential motor mount wear as the cause of the vibration.

 

[Richard McDonald]

That’s a normal Beneteau set up. What you see coming out of the skeg is a stainless shaft log. Sealant is applied where the log comes out of the skeg. The shaft goes through the log with a black rubber cutlass bearing at the very back of the log. They usually have a dripless shaft seal and a way of injecting water behind the seal. The water flows between the log and the shaft, out the grooves in the cutlass.

The fact that there was no lateral play in the shaft suggests that the cutlass is adequately lubricated, otherwise it would heat up and wear out.

I would lean toward potential motor mount wear as the cause of the vibration.

David, thanks for the feedback. The engine has a little over 1,300 hours showing up on the digital display. Would it be normal on a 2006 Beneteau 423 or similar to have "tired" motor mounts?
Richard

 

[Alfa]

Richard,

1600 hours for 2006 Diesel engine indicate very low use and if engine vibration is caused by engine mounts it is most likely attachments of the mounts rather than worn rubber. Check if all upper and lower nuts of the engine mount are tight. Problem with engine mounts are easy to spot when engine is running in NEUTRAL; from idling speed to higher RPM.

If you could see …”significant visual deflection of the shaft under way”… ”and significant (vibrations) intensity”...at higher RPM in the cockpit it, it could be engine/shaft misalignment, bent shaft or worn out cutlass bearing (usually) by unbalanced propeller. Shaft play in worn out cutlass bearing is is usually not lateral but UP and DOWN.

Vibrations caused by unbalanced propeller (and worn out cutlass bearing) is much easier to recognized with free wheeling fixed propeller when running with wind than under way with engine. Momentary increase of speed when sailing will produce vibration in cockpit floor.

If you like the sailboat, except those vibrations, estimate cost of repair work and buy it.. Work on Beneteau Oceanis drive train is very easy.

 

[Richard McDonald]

Richard,

1600 hours for 2006 Diesel engine indicate very low use and if engine vibration is caused by engine mounts it is most likely attachments of the mounts rather than worn rubber. Check if all upper and lower nuts of the engine mount are tight. Problem with engine mounts are easy to spot when engine is running in NEUTRAL; from idling speed to higher RPM.

If you could see …”significant visual deflection of the shaft under way”… ”and significant (vibrations) intensity”...at higher RPM in the cockpit it, it could be engine/shaft misalignment, bent shaft or worn out cutlass bearing (usually) by unbalanced propeller. Shaft play in worn out cutlass bearing is is usually not lateral but UP and DOWN.

Vibrations caused by unbalanced propeller (and worn out cutlass bearing) is much easier to recognized with free wheeling fixed propeller when running with wind than under way with engine. Momentary increase of speed when sailing will produce vibration in cockpit floor.

If you like the sailboat, except those vibrations, estimate cost of repair work and buy it.. Work on Beneteau Oceanis drive train is very easy.

Alfa, thanks for the insight. Did run the engine in neutral a couple of days ago and no engine vibration. Vibration happens only when in gear and more apparent from 1500rpm with increased intensity up to 3000rpm. Suspecting prop, shaft and cutlass. Actually working on cost estimate to purchase as is and take care of the issue. In that case may be inclined to install a new Max Prop.

Not sure how difficult to replace the cutlass on the Beneteau 423, will research that more.

Richard

 

[Alfa]

Richard, good decision. You are right suspecting prop, shaft and cutlass, but you still have to check engine alignment.
Suggest you start again from checking shaft play in the cutlass bearing.

1. Grab the prop and vigorously check if shaft has any movements, lateral and UP AND DOWN. If vibrations are due to propeller out of balance, some wear of cutlass bearing could be present, but not always.

2. Check concentricity of shaft in the stern tube:
With propeller still attached to the shaft, inside the boat: check shaft between shaft seal and shaft flange for crevice corrosion, or impurities which may damage lip seals inside Volvo shaft seal. If necessary, use soft Scotch Brite and than clean the shaft with wet cloth soaked in soupy water. Remove clamp from the Volvo-Penta shaft seal and rotate/slide the seal FWD.

ATTENTION: When working on shaft seal, do not exert any significant force on the barbed fitting or rubber hose attached to the stern tube to prevent barb fitting breakage.

Visually observe concentricity of the shaft in the stern tube. Make short wedge out of cardboard or plastic to check distances from shaft to the stern tube ID, to get approx distances at TOP, BOTTOM, STBD and PORT. As you know, engine must be aligned to the shaft located in the centre of the stern tube.

NOTE: Since you are new to Beneteau Sailboat and probably to Volvo-Penta shaft seal, you must know the following:
Volvo Shaft Seal is a radial, double lip, self-aligned rubber seal. The AFT lip seal is lubricated and cooled by sea water. The FWD lip seal (back-up seal), is not lubricated by water and must be lubricated once a year with water resistant grease. To provide supply of water, bronze barb fitting is threaded and sealed with epoxy in the stern tube. Some sailboats have passive supply of water by 3/8” rubber hose from a thruhull, other boats by flow of water from the heat exchanger.
Volvo seal must be vented to remove trapped air when boat is launched in the water. In Beneteau Oceanis venting is done by squeezing FWD end of the seal until water drips out. In Beneteau First, barbed fitting in the stern tube is venting trapped air via hose when splashed.

3. Remove cutlass bearing:
Pour soapy water from inside the boat into stern tube until it flows outside from the cutlass bearing. Outside, remove 2 screws from the stern tube exiting from the skeg (the whole length of the stern tube is precision cast GRP with only last portion clad in thin tube of SS). Have ready spray bottle with soapy water during removal of the bearing.
With rubber gloves, grab cutlass bearing FLANGE AND SHAFT with both hands and ask helper to rotate the prop left and right as you rotate flange with shaft pulling the flange out. When you manage to remove short length of the bearing, stop and remove propeller.
Don't remove completely cutlass bearing at this time. The shaft flange is still attached to transmission flange. If shaft did not had any play it is good to be used. If you have to replace cutlass bearing, do it when you are ready. No need to put any additional stress bending shaft 7.5mm.

4. Remove propeller:
Remove Zinc from propeller nut. In Beneteau, prop nut is secured by thin SS washer bent against flat of the nut. On your first picture, washer is visible but not bent. Check the other side and unbend before unscrewing propeller nut.

5. Balance propeller.
Even if you are considering installing Max Prop, you should balance your fixed 3 blade prop to know if unbalanced prop was causing vibrations. Your pics show not damaged propeller, so most likely shaft is strait. Vibrations probably are due to unbalanced propeller OR engine misalignment.

More next time: out of balance propeller in 2 year old Beneteau Oceanis 31 with originaly installed propeller at Beneteau US.

NOTE: Now It is good time to check if barbed fitting epoxied in the stern tube is not PLUGGED WITH SALTS (especially if you don’t know if PO checked or replaced barb fitting). Gently, not breaking the barb fitting in the process, remove from the fitting 9.5mm I.D. rubber hose. IT IS SAFER TO CUT THE HOSE very close to the fitting to prevent breakage. When hose is removed, check if you can blow air through the fitting. If not, poke with stiff wire (small size Allen key will work). Best will be to replace existing fitting with a new one.
If interested I will show you (and other Beneteau owners) how to make DIY, never corroding Titanium fitting.

Attached picture shows completely blocked with salts, barbed fitting removed from Beneteau First 45.5 in my marina.
ALFA

 

[Richard McDonald]

Richard, good decision. You are right suspecting prop, shaft and cutlass, but you still have to check engine alignment.
Suggest you start again from checking shaft play in the cutlass bearing.

1. Grab the prop and vigorously check if shaft has any movements, lateral and UP AND DOWN. If vibrations are due to propeller out of balance, some wear of cutlass bearing could be present, but not always.

2. Check concentricity of shaft in the stern tube:
With propeller still attached to the shaft, inside the boat: check shaft between shaft seal and shaft flange for crevice corrosion, or impurities which may damage lip seals inside Volvo shaft seal. If necessary, use soft Scotch Brite and than clean the shaft with wet cloth soaked in soupy water. Remove clamp from the Volvo-Penta shaft seal and rotate/slide the seal FWD.

ATTENTION: When working on shaft seal, do not exert any significant force on the barbed fitting or rubber hose attached to the stern tube to prevent barb fitting breakage.

Visually observe concentricity of the shaft in the stern tube. Make short wedge out of cardboard or plastic to check distances from shaft to the stern tube ID, to get approx distances at TOP, BOTTOM, STBD and PORT. As you know, engine must be aligned to the shaft located in the centre of the stern tube.

NOTE: Since you are new to Beneteau Sailboat and probably to Volvo-Penta shaft seal, you must know the following:
Volvo Shaft Seal is a radial, double lip, self-aligned rubber seal. The AFT lip seal is lubricated and cooled by sea water. The FWD lip seal (back-up seal), is not lubricated by water and must be lubricated once a year with water resistant grease. To provide supply of water, bronze barb fitting is threaded and sealed with epoxy in the stern tube. Some sailboats have passive supply of water by 3/8” rubber hose from a thruhull, other boats by flow of water from the heat exchanger.
Volvo seal must be vented to remove trapped air when boat is launched in the water. In Beneteau Oceanis venting is done by squeezing FWD end of the seal until water drips out. In Beneteau First, barbed fitting in the stern tube is venting trapped air via hose when splashed.

3. Remove cutlass bearing:
Pour soapy water from inside the boat into stern tube until it flows outside from the cutlass bearing. Outside, remove 2 screws from the stern tube exiting from the skeg (the whole length of the stern tube is precision cast GRP with only last portion clad in thin tube of SS). Have ready spray bottle with soapy water during removal of the bearing.
With rubber gloves, grab cutlass bearing FLANGE AND SHAFT with both hands and ask helper to rotate the prop left and right as you rotate flange with shaft pulling the flange out. When you manage to remove short length of the bearing, stop and remove propeller.
Don't remove completely cutlass bearing at this time. The shaft flange is still attached to transmission flange. If shaft did not had any play it is good to be used. If you have to replace cutlass bearing, do it when you are ready. No need to put any additional stress bending shaft 7.5mm.

4. Remove propeller:
Remove Zinc from propeller nut. In Beneteau, prop nut is secured by thin SS washer bent against flat of the nut. On your first picture, washer is visible but not bent. Check the other side and unbend before unscrewing propeller nut.

5. Balance propeller.
Even if you are considering installing Max Prop, you should balance your fixed 3 blade prop to know if unbalanced prop was causing vibrations. Your pics show not damaged propeller, so most likely shaft is strait. Vibrations probably are due to unbalanced propeller OR engine misalignment.

More next time: out of balance propeller in 2 year old Beneteau Oceanis 31 with originaly installed propeller at Beneteau US.

NOTE: Now It is good time to check if barbed fitting epoxied in the stern tube is not PLUGGED WITH SALTS (especially if you don’t know if PO checked or replaced barb fitting). Gently, not breaking the barb fitting in the process, remove from the fitting 9.5mm I.D. rubber hose. IT IS SAFER TO CUT THE HOSE very close to the fitting to prevent breakage. When hose is removed, check if you can blow air through the fitting. If not, poke with stiff wire (small size Allen key will work). Best will be to replace existing fitting with a new one.
If interested I will show you (and other Beneteau owners) how to make DIY, never corroding Titanium fitting.

Attached picture shows completely blocked with salts, barbed fitting removed from Beneteau First 45.5 in my marina.
ALFA

Alfa, thanks for the detailed response and instructions. Much appreciated!
Should be closing on the 423 in the next few days and will be tackling the vibration issue.
Already shopping for a new replacement prop. Will probably opt for a feathering one.
Since I sail the great lakes, no salt issues for me, until we decided to sail down south, but probably some other owners may like to know more on your DIY fitting.
Thanks again.
Richard

 

[Bob S]

how to make DIY, never corroding Titanium fitting.

I'd be curious!

 

[Hollyberry]

......
Already shopping for a new replacement prop. Will probably opt for a feathering one.
......

I'm really missing the Max Prop that we had on the last boat. It's a beautiful piece of engineering, and I think you'll be very happy with a 3 blade once you sort out the vibration issue...

Best of luck...

 

[arf145]

I was thinking mounts as I read this. That prop is amazingly clean. BTW, my Bene came with a MaxProp from the previous owner and I love it.

 

[Alfa]

To Bob S: I’m on vacation and don't have access to all my photos now. Will write when back on Volvo Seal and DIY Titanium barbed fitting.

Richard, for your info: two years old Beneteau Oceanis 31 (with original 3 blade fixed prop installed by Beneteau US) had very small up/down play in the cutlass bearing, but no significant vibration on power or sail during trials. However, few months later vibrations could be detected in the cockpit when sailing at at 7kn or higher. I build simple device shown below to check prop balance and noticed that one blade in the prop was 1/8” longer and thicker; prop obviously out of balance. By using angle grinder with 60gr sand paper and polisher, I easily restored prop balance.

 

[Richard McDonald]

Alfa: I'm now a 2 sailboat owner for a while! Closed on the "new" for me 2006 Beneteau 423 on Thursday and will be looking for a good home for my 1979 H37C Cherubini which has been a great ride for 18+ years with many great memories sailing the Great Lakes.

Hauled out the Beneteau 423 on Friday to further investigate the vibration issue and remove the old fixed blade prop today.

Found:
1) up/down play in the cutlass bearing, more then I would like to see.
2) 1 blade of the fix blade prop bent back by at least a 1/4"+ compared to the other 2.
3) After bending back the SS washer, the prop nut came loose with almost no effort and the prop was pulled off also with little effort, which leads us to believe that it was probably not seated completed tights on the prop shaft.

Will check out the prop shaft in the next few days.
I now have a new PYI 3 blade Max-Prop on order and will have the old prop serviced locally and keep as a spare.
I intend to replace the cutlass bearing, now need to find where I can purchase it. PYI suggested I contact Ward at Beneteau USA. Will try that on Monday.

Planning to sail the new baby from Lake Erie to Lake Michigan to our slip in Milwaukee WI in August, should be a nice 3 week sailing vacation!

Richard

 

[BigEasy]

NOTE: Now It is good time to check if barbed fitting epoxied in the stern tube is not PLUGGED WITH SALTS (especially if you don’t know if PO checked or replaced barb fitting). Gently, not breaking the barb fitting in the process, remove from the fitting 9.5mm I.D. rubber hose. IT IS SAFER TO CUT THE HOSE very close to the fitting to prevent breakage. When hose is removed, check if you can blow air through the fitting. If not, poke with stiff wire (small size Allen key will work). Best will be to replace existing fitting with a new one.
If interested I will show you (and other Beneteau owners) how to make DIY, never corroding Titanium fitting.

Please post photos & details of your DIY titanium stern tube fitting. Thanks.























































7

 

[Brad Gregg]

Sent a PM to Richard in case he doesn't see this, but also wanted to post here to ask what the eventual FINAL fix was for this issue. I have something very similar going on with one caveat -- mine vibrates above 1500 rpm in forward gear, but doesn't do anything in reverse. Nice and smooth.

 

[NYSail]

Alfa, thanks for the insight. Did run the engine in neutral a couple of days ago and no engine vibration. Vibration happens only when in gear and more apparent from 1500rpm with increased intensity up to 3000rpm. Suspecting prop, shaft and cutlass. Actually working on cost estimate to purchase as is and take care of the issue. In that case may be inclined to install a new Max Prop.

Not sure how difficult to replace the cutlass on the Beneteau 423, will research that more.

Richard

replacing the cutlass is not a big deal….. just have to remove the prop, then slide the cutlass out. The new one will go in very tight. I lightly sanded the exterior of the cutlass bearing then used dish soap on the inside and out. Takes some effort to slide into place. One challenge is the set screws. The cutlass has indentations for them but in wrong place. I used a heated (red hot) drill bit once the cutlas was in place and it cut / melted it perfectly.
Regarding your vibration, I would suspect the engine mounts need some attention. I have. Yanmar so different mounts but I’m sure for the volvo there are specs for the rubber clearance. Check tightness as well.
Good luck
Great boat!

 

[Brad Gregg]

For what it's worth, my vibration was related to a worn out max prop. Two mechanics, on the hard, looked at it and said it was fine. More recently a diver looked at it and said it was fine. As soon as I touched it during a haul out, it was clear the blades had way too much play. This was causing a nasty vibration in forward but nothing in reverse. From the feel of the blades, I would have expected to feel it in reverse as well. Replacing the max prop with a fixed blade completely eliminated the vibration.