Re: [Amel Yacht Owners] Expected RPM at WOT


 

Porter,

Some random thoughts...read the last paragraph/suggestion.

I believe any alignment problem will present itself with considerable vibration.

I think you should press Volvo, but I guess you could disconnect the Vetus coupling and see what RPM you can achieve with the transmission in gear. I don't know what the RPM should be in this case, but probably very close to the RPM achieved in neutral. 

I believe an alternator could be a source of too much load, however, if you achieve high RPM in neutral, the alternator(s) can be eliminated.

We must remember that the Volvo computer is designed to prevent sending more fuel to the injectors than the engine is capable of burning. This minimizes pollution, which was the primary goal of the D3. The best example of pollution caused by sending more diesel to diesel cylinders is exhibited by large trucks accelerating with plumes of black smoke (unburned diesel).

What about this scenario:
Remembering that Volvo specified the prop, what about an RPM test with no prop? I believe if you achieve high RPM, you have eliminated all connected sources of friction and proven that the only source of your problem is the Volvo engine and probably, wiring, sensors, or computer.

I hope this helps.

Best,

CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus

Amel School  http://www.amelschool.com
720 Winnie St
Galveston Island, TX 77550

+1(832) 380-4970

Any opinions and conclusions expressed in this message are solely those of the author and should not be construed as representing the opinion of an expert. Manufacturers' and Expert's precautions must be considered when dealing with mechanical and/or electrical systems to ensure that you are NOT harmed, and/or the device and/or system is NOT ruined. If in doubt, do not touch any mechanical and/or electrical device or system referred to above.


On Fri, Aug 31, 2018 at 8:27 AM Porter McRoberts portermcroberts@... [amelyachtowners] <amelyachtowners@...> wrote:
 

Bill 

As always I really appreciate your thoughts on this.. I think it is the computer or sensors too. Also we were getting 2600 rpm before that long block exchange (with poor compression). 
So today I’ll try and wiggle the fixed prop off and run the naked spline. 

And I’ll take you up on your offer of a letter to Volvo. 

Thanks again Guru

Porter. A54-152

Excuse the errors.  
Sent from my IPhone 

On Aug 30, 2018, at 4:36 PM, Bill Rouse brouse@... [amelyachtowners] <amelyachtowners@...> wrote:

 

Porter,

If you can easily spin the prop in neutral with the shaft brake OFF, the C-drive isn't adding friction.

I think that you have two remaining possibilities:
  1. The brand new transmission is faulty, when it was not faulty before the long block change (I think very, very unlikely)
  2. Volvo Computer is not allowing higher RPMs for some unknown reason.
With a new transmission, a changed prop (which Volvo spec'd in the 1st place), and the c-drive tested, I have to believe that the problem is with the Volvo Computer. There is one more reason I point to the Volvo Computer: Of all of the possibilities, it is the most likely because of our combined experience with Volvo, the D3 and its computer.

I will happily write Volvo a more detailed explanation when you get to that point.

Best,

CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus

Amel School  http://www.amelschool.com
720 Winnie St
Galveston Island, TX 77550

+1(832) 380-4970

Any opinions and conclusions expressed in this message are solely those of the author and should not be construed as representing the opinion of an expert. Manufacturers' and Expert's precautions must be considered when dealing with mechanical and/or electrical systems to ensure that you are NOT harmed, and/or the device and/or system is NOT ruined. If in doubt, do not touch any mechanical and/or electrical device or system referred to above.


On Thu, Aug 30, 2018 at 2:05 PM Porter McRoberts portermcroberts@... [amelyachtowners] <amelyachtowners@...> wrote:
 

Nick. Yes. Thank you. 


Re WOT out of gear: 3100rpm

The transmission is fairly new:  replaced in he spring. 


Re friction within the cdrive. 

With engine idling in neutral, brake open I swim under the boat and can easily spin the prop. 

How can I better evaluate resistance in the system?: motor—New ZF tranny—vetus(friction??)— cdrive— prop. 

I think the next step is to take the fixed prop off. 
I need a gear puller to get it off I think (which I don’t have and need to get (any recommendations?).. Unless anyone has another suggestion? Tying the autoprop puller to the fixed prop using low stretch amsteel?  

Again all very good suggestions. 

Let’s say it is the cdrive. What then??????

Thank you all!!

Porter 

Amel 54-152

Excuse the errors.  
Sent from my IPhone 

On Aug 30, 2018, at 12:47 PM, Nick Newington ngtnewington@... [amelyachtowners] <amelyachtowners@...> wrote:

 

Sorry Porter,


Just going over the email again.

You have max RPM of 2200 at WOT with the new fixed prop, right? If so that can not be correct. It should be around 2850.  I doubt Amel would supply a spare prop that is not correct for the engine, at least not to that degree. To be so far from the desired RPM at WOT may cause problems with your new engine. 

What RPM can you achieve out of gear? 

What about the C drive? Have you checked that is working without friction? 


On my 54 with 2006 D3 110 and the Autoprop I get 2850 at WOT, with a clean prop and hull. 

Nick



On 30 Aug 2018, at 15:46, Porter McRoberts portermcroberts@... [amelyachtowners] <amelyachtowners@...> wrote:

Thank you everyone for your thoughts re our engine woes they are quite appreciated. 


May I ask thoughts re expected rpm during WOT with the supplied fixed prop on the Amel 54?


Has anyone with the fixed prop determined an observed RPM with WOT?  Volvo is telling me that they think 2200 is due to too large a prop. Now I know the H6 is a slight over propping, reducing the expected 3100-3200 Volvo D3-110 to your observed 2900ish range. 

But 2200 (our WOT RPM with the fixed prop in calm seas) is much lower than 2900, and I have a hard time thinking such a great drop is due to the lack of prop arm adjustment for appropriate bite as seen with the autoprop. 

Any data would be very appreciated. 

Many thanks

Porter Helen Grace and Lilly
S/V Ibis A54-152
Isla Contadora, Panama

Excuse the errors.  
Sent from my IPhone 

On Aug 30, 2018, at 5:40 AM, Nick Newington ngtnewington@... [amelyachtowners] <amelyachtowners@...> wrote:

 

Hi Porter,

I watched the video that is a massive reduction in RPM. Is their black smoke when it does that because it looks like the engine is seriously overloaded and about to stall?

So the fixed blade prop stops it right. Therefore there is nothing wrong with the engine itself.

Thus it must be something to do with the Bruntons Autoprop, which is a variable pitch prop.

The pitch varies automatically in order to maximise efficiency. "The Autoprop blades, unlike those of conventional propellers, maximise the thrust delivered whatever rpm the yachts engine is running at “

quote from Autoprop website.

So if the thrust  is maximised at all times then load on the engine must vary a bit. Just like say the big alternator kicking in when one runs a heavy load off it, say a toaster for example. So I would expect a slight variability in the rpm as the load on the engine varies but not like in your video.

Agreed there is something wrong with the prop. You could strip it down yourself, it is pretty easy, before returning for service.


Nick

Amelia (Amel 54 019) back at home for a bit.

On 30 Aug 2018, at 10:44, trifin@... [amelyachtowners] <amelyachtowners@...> wrote:

Porter,

Wow, that is a pretty major "wander" in the video, so glad to see it was resolved by changing prop.  
Your numbers look ok, except for WOT 2200 seems awfully low. I think you do need to follow that up with Volvo, particularly with the fixed prop now in place.

I checked my WOT this morning in flat water/no wind and it was stable at 2920rpm.  

I also took a short video of the wandering I was referring to, its in the" ZF25 Transmission" folder in the files section.  It shows a variation from 1170 to 1210, difficult to hear the engine note on the video, but 40rpm variation is just enough to make the ears prick up!. Given yours and Mohammad's observations, i'll put it down to propeller effects..

I've also uploaded my Sea Trial results from a few weeks ago after we had the gearbox fitted.
It was a bit choppy and breezy, so the speeds are a bit lower than we get in flat water.

Danny, and others - I've solved my oil leak.  Not sure exactly what to attribute it to.
I found an extra 1/4 turn on one of the fwd end sump bolts, but I've also done my regular oil/filter change including replacing the Oring on the oil filter cap.  One of those things solved it - I suspect the filter cap may have been the culprit.   

Cheers
Dean
SY Stella
AMEL 54 #154






Join main@AmelYachtOwners.groups.io to automatically receive all group messages.