Flange Couplings

[Stu Jackson]

An update about a recurring issue:

In http://c34.org/bbs/index.php?topic=1134.0 we discussed the bolts at the flange coupling.  That was in 2003.  In 2004 and 2005 I also had to tighten and replace some or more of the bolts and nuts.

This weekend, late January 2007, we had the same experience of rough engine operation.  The engine worked fine with no hull vibration in neutral, but in gear the noise came back. 

When we docked I checked and three of the four nuts on the flange coupling bolts were starting to back off.  The bolts should be fine thread, not coarse.

I tightened them all, and everything was fine on our return cruise.

Just another reminder for all that if there is unusual engine noise when in gear, check out all of the other possible symptoms, but also check the flange bolts and nuts perhaps as a first step, which may eliminate the problem.  Many believe their engines could be out of alignment and start on the engine mounts, which not be the appropriate first step and could make things worse if the engine was properly aligned already.  Also check engine operation out of gear -- if it sounds smooth, it's something in the drive train.  Transmission oil should be changed regularly.

While "down there" I also checked the stuffing box, which needed a 1/8 turn.  Good time to do both.

[Craig Illman]

Stu -

I doesn't sound like your lock washers are very effective. Maybe you need to replace them or supplement them with a drop of locktite or lock nuts. When I did my motor mounts a few weeks ago, it was pretty challenging to reach and get adequate torque to break my flange bolts loose.

Craig

[Ron Hill]

Took me a minute to figure out which "flange" youall were talking about!!
 
As I wrote in the Mainsheet tech notes and in pictures, you need to make "slippage marks" and not completely trust lock washers. 
The nut or bolt head side should be where it is visible.  Then use white or red finger nail polish and make a SMALL stripe from the bolt head on to the stationary surface or from the nut onto the bolt threads.  At a glance you can see when that small stripe is broken - it means something is no longer tight.  I also have slippage marks on the top nuts on the engine mounts, but used a thin line magic marker.
A few thoughts.      

[cwmarine]

Good advice regarding the need to check the flange connection to be certain it is tight.  On a very related topic, has anyone used a "drive saver" or flexible coupling application?  I have been considering the flexible coupling from R&D Marine.  Given the cost, I am seeking some input as to the value of adding this.

Regards,  Chuck
S/V Glory #1602

[Ron Hill]

Chuck : I've had both and wouldn't waste my money on a "Driversaver"!!  Get a flexible coupling and you'll end shaft alignment.  Mine happens to be a Vetus, but other flexible couplings are also OK. 
Now that I see you have an M35B engine - Just make sure that you have space between the transmission and the packing gland for that flex coupling. 

Another way to make sure that nuts don't back off - is to use self locking nuts or a second (jam) nut if you don't want to make slippage marks!!
A few thoughts.     

[Rocco]

Chuck,

I investigated both a Drive Saver and Vetus flexible coupling, but neither would work on the MKII with a PSS shaft seal; there isn't enough shaft left between the coupling with Drive Saver or the Vetus coupling to properly adjust the PSS bellows (due to the extra length of the M35).  My MKII (Hull #1347) originally came with a stuffing box which I upgraded to a PSS.  I believe the newer MKII's come with the PSS now (I could be wrong about this), if so, I'm not sure when the "cutover" occured.  If you have a PSS, be sure to measure things up to ensure there is enough room to accomodate the new coupling arrangement and still allow the SS rotor on the PSS to slide forward to the point that it just contacts the carbon sealing flange (for proper adjustment in the future).

Regards,
Rocco

[cwmarine]

Thanks to both of you for the response.  My 2002 MkII came with a traditional stuffing box and the locking nut.  Your point is well taken regarding the ability to accommodate the flex coupler.  I will recheck this area again to be certain.  During my last haulout, and shaft zinc replacement, I tried to anticipate the aft movement of the shaft with a coupler installed. As a result, I positioned the shaft zinc accordingly.  I was concerned that if the zinc was too close to the leading edge of the shaft strut, it could interfere with the flow of water to the cutless bearing.

Again, thanks for the input.

Chuck
S/V Glory #1602