Shearing bolts on elastic coupling D2-55C

[xhogpilot]

I have a lagoon 440 with volvo penta d2-55C engines and s130-b sail drives.

The bolts on the elastic coupling (shock absorber between the flywheel and the sail drive during gear change)sheared off...under normal careful shifting. As I just bought the boat, I assumed this occurred due to previous user wear or throttle technique.

I replaced the crankcase housing, elastic coupling, endplate, engine mounts and of course the 6 bolts. All bolts were torqued to spec.

Afters less than 5 hours of engine use, 2 adjacent bolts out of 6 sheared (flush with the flywheel) with no apparent damage or backing out of the other 4 bolts.

Machine shop tested the balance of the flywheel and indicated it was well within limits (14lbs at 3000 rpm).

During all of this, the clutch on the other engine was slipping, so a clutch and seal kit were installed. While taking that apart, it was noticed that the elastic coupling had no signs of wear other than there was much more play between the two plates it's comprised of. So, I replaced that, as well. This engine has less than 5 hours on it since the repair and last night on start up, created an unpleasant and familiar sound like that of a bolt head getting jammed inside the flywheel housing.

All repairs were done very carefully, with attention to detail, and all torque values followed. I observed them all myself.

Anyone have any knowledge of this issue and, if so, share some insight.

If not, don't.

Thanks

[Captsteve53]

OK, at the risk of dire comments i will relate an issue i found on A Volvo Sail drive some years back with the same issue, as my memories seem to be not so good lately I cant confirm the model but pretty sure it was your engine the
Volvo 55 but the sail drive model not sure??

Any way at time there was an issue with the flexible coupling securing hole size they were all sloppy (even from new) so the fix was was to make up the small bushings to take the sloop out of the holes being careful not to make them thicker than the coupling,

We made sure that high tensile (grade 8 ) bolts were used and removable thread locker (both drives on this cat had the same problem) and it seemed to us a manufacturers screw up, obviously (well to me) any mounting holes that are not a tight fit with the bolts will cause them to move(even if marginally) thus causing the sheering,

Bottom line the Cat is still in the local Marina and 6 years later still sailing on with no issues,

May be worth looking at yours?(Dont want to waste your time!)

Cheers Steve

[DougR]

There were a couple of issues with the torsional dampers, their attachment to the flywheel, and the alignment with the flywheel housing that could result in problems with the attachment bolts. However I don't recall that there were stand alone bolt shearing problems that weren't related to one of the other issues.

- The original damper that was supplied had an aluminum flywheel attachment flange that was about 4.5 mm thick, as seen in the attached photo. Along with this 4.5mm thick flange there was a 6mm spacer (also in the photo) that went under the lockwasher under the Allen screw head. This provided 10mm of bolt length between the head of the screw and the threads in the flywheel. This "free" bolt length is necessary to allow the screw to stretch a bit when torqued, and the stretch maintains tension on the damper to keep it from slipping and to also help prevent the screw from loosening. Unfortunately the strength of the 4.5mm flange was inadequate for hard use and there were cases of the flange failing with disasterous results.

- The original damper was replaced with a damper with a flange approximately 10 mm thick, and in this case the 6mm thick spacer was no longer necessary and it was deleted. There was a parts bulletin to make dealers aware that dampers and spacers shouldn't be mixed up. As seen in the photo, the damper is machined with a pilot that locates in a female pilot on the flywheel and this provides the centering effect necessary for the damper, leaving the bolts to provide only the clamping force to prevent the damper from slipping on the flywheel face. Over time, the second damper was replaced with a third with more mass added to smooth small torsional vibrations, but the basic design remained the same.

- There was another problem that arose for a brief period of time that could effect the damper, and this was a misalignment of the locating dowel holes in the flywheel housing that locate the flywheel housing on the engine block. Mislocated dowels result in the centerline of the transmission or saildrive input shaft being offset from the centerline of the crankshaft/torsional damper. This results in the damper hub effectively osscilitating within the outer portion of the damper when the engine is running, and could cause damper wear and possibly loosening of the attachment bolts. Again, there was a service bulletin about this problem and the defective housings should have been replaced.

- As mentioned above, I don't recall particular issues with the screws loosening on their own without help from another problem, but as stated by Capt. Steve, these screws and flywheel threads should be cleaned with an effective solvent and a thread locking liquid used when ever installed. Going a step further, the screw heads could be drilled and locking wire installed for a belt and suspender approach.

Hope this is helpful.

DougR

[xhogpilot]

Thanks to you both. My problem apparently is that I was installing the spacer as per the exploded parts diagram when I shouldn't have. Expensive.

[xhogpilot]

I flew out of Clark AB 1981-83. Had some good times on the base at Subic. Thanks again.

[Cordylia2]

Hello , i bought a sailboat recently that is powered with a d2\75 engine. 10 yrs old and less than 600h on the engine . i quickly realised there was something wrong with the coupling in the transmission. I took everything apart and the flex coupling was definitely bad, i proceed to replace it. As we were setting out for a year cruise from canada to Panama, all good for a while , but now 100hrs into it and the coupling is going bad again, since they cost around 1000$ , i really need to understand what is going wrong , DougR : you are talking about a misalignment of flywheel housing dowel ... Do you have more info on this service bulletin/recall , my feeling and understanding points toward this explanation as everything else look right ! Any other ideas are welcome .

Best regards

[DougR]

Hello Cordylia2,

Unfortunately I'm not at my primary residence at the moment so I can't give you the specific information on the service bulletin in question. However as mentioned, the problem was that the machined pilot for the gearbox/saildrive attachment in the flywheel housing was not centered on the crankshaft centerline, so the input shaft for the transmission was slightly offset from the crankshaft CL. This happened because the front surface of the flywheel housing was slightly mismachined.

The instructions for checking this were to insert a long bolt with a locknut in one of the tapped holes on the flywheel and measure the distance between the bolt and the edge of the flywheel housing pilot at numerous points around the opening. An allowable tolerance was provided to determine if the housing should be replaced.

Any decent VP diesel dealer should be able to provide a copy of the bulletin, or if you're in the US you can call VP at 757-436-2800. VP Canada is in Vancouver, but I don't know the # off the top of my head.

DougR

[NordicCruiser]

It is quite a long time ago since the last discussion in this post. But I am currently investigating some vibration issues on my D2-55C and saildriver 130S-B. I got some information from a local dealer to check the flexible coupling which is discussed in this topic. Does anybody have access to the product bulletins mentioned above? I would like to check which of those are relevant to my engine / saidrive revision.

Best regards
NordiCruiser

[GordMay]

Greetings and welcome aboard the CF, NordicCruiser.

[NordicCruiser]

Thanks a lot, I have been following for a while and appreciate the good technical discussions. So I finally created an account.

[NordicCruiser]

Does the flywheel housing need to be removed to dismount and exchange the flexible coupling? On images, It is difficult to see i there is enough diameter in the opening to get the coupling out when the housing is still mounted.

[DougR]

Your local VP dealer should be able to do an online search on the VP "partner network" by your engine serial number to see whether there are any service or parts bulletins which apply to your engine. Actually, now that I think about it, I think you can go online to the VP website with your serial number and do this search yourself....

The early D2-55 engines required the flywheel housing to be removed to change the torsional damper, but the flywheel housing on later engines like your "C" version were made with " notches" which allowed the damper to be removed and replaced with the housing in place.

DougR

[NordicCruiser]

Thanks DougR, I have already checked the engine serial number against the VP website and there is nothing shown for my engine. Last year I was also asking a VP partner and he did not mentioned something either.

Concerning the housing, are you really sure that the notches already came on the "C" version? Looking at the partscat online the housing has only been amended in design from "F" version? If you compare "C" and "F" dravings, is that the difference you mean?

"B" to "E" version
https://www.marinepartseurope.com/da...0-21-5301.aspx

"F" version
https://www.marinepartseurope.com/da...-21-35209.aspx

[DougR]

Well, my recollection is that the introduction of the " notches" which you see on the "F" drawings came very early on in the production, some where in late "A" or early "B" series engines. The drawing which is shown for the early series engines shows the housing without notches, but most likely the drawing was just never updated to show the notches.

My own D-55 engine is a "C" version like yours, and it has the notches. However I built this engine up from various warranty parts during the time I was at VP, and I did change the housing because of some stripped bolt holes. My recollection is that both the original and replacement housing had notches. At that time it was well before the "F" version and the notches were there.

The only difference between the two parts shown in the parts breakdown is that the hole for the tachometer sender, on the top of the housing, has changed diameter.

DougR

[NordicCruiser]

Thanks DougR, from your experience, how likely would you suspect the torsional damper mentioned here to be responsible for some vibrations that I have about 1.200 to 1.800 RPM? As I first got the boat, I ignored it but it was always a bit annoying. Then I realized, that the enginge was making ticking noise, like as you are using a hammer and ticking on metal. It was more noise on the port-side so I assumed something was in the prop and touching the hull. But it wasn't. I have ruled out propeller (changed to new) and propeller shaft, Installed a new cone kit as well. Then I realized that the bolts from the engine mounts on the port side were loosening from time to time, possible produching the ticking noise. I thought, that was it now everyting ist ok, but then I got the chance to sail the same boat with same drive, prop and engine on a fair. It was new and there was a huge difference. Everything was very smooth. So a VP advised me to check that flexible coupling. In Idle, I was thinking: there is no vibrations, but the damper is also turned in idle - however without load. So it might only be an issue with load. It is much work to check that, so one could make the saildrive diaphragm in the same run. What else could it be? Any idea how to check the engine mounts?