bukh dv 24

[cass1]

Hi everyone  THis is my first post  .Im fitting a dv24 into my boat .I was advised by a bukh specialist that it had to be rubber mounted or the mountings could break .I have done so but  the thing vibrates far too much  Have i been misinformed ? The engines have counter balancers and my experience with twin engines says solid mount them Hoping someone on here can help .

[mrsmelly]

Brilliant choice of engine, they can not be bettered. Cant remember what my mounts were on the boat with that particular engine. Tony will be along soon I think as he knows his stuff and had a Bukh on his boat.

[Athy]

10 minutes ago, mrsmelly said:

Brilliant choice of engine, they can not be bettered. Cant remember what my mounts were on the boat with that particular engine. Tony will be along soon I think as he knows his stuff and had a Bukh on his boat.

He's the man who wrote the bukh about it, asyermightsay.

 

Welcome Cass, I hope you and your (rather desirable) engine will soon be peacefully co-existing.

[WotEver]

@Tony Brooks?

[Flyboy]

1 hour ago, cass1 said:

Hi everyone  THis is my first post  .Im fitting a dv24 into my boat .I was advised by a bukh specialist that it had to be rubber mounted or the mountings could break .I have done so but  the thing vibrates far too much  Have i been misinformed ? The engines have counter balancers and my experience with twin engines says solid mount them Hoping someone on here can help .

Have you got the correct rubber hardness mountings for this engine ?  Also are they adjusted too high up the threaded studs?  A picture of your installation would be helpful.

Edited May 15, 2020 by Flyboy

[cass1]

The mounts were sold to me by the dealer for the engine   The only mod i had to make was to extend the brackets out to suit the engine bearers  My next job was to try to move them nearer to the motor which is quite a job The bracket was just bolted onto the top of the rubber  Any height adjustment was by shimming under the mount  Just for your interest the engine is in to replace the bolinder munktel which has now completely worn  out RIP {rest in pieces} .

[Batavia]

Try Nick at TW Marine - very knowledgeable and helpful.

[cass1]

Nick sold me the mounts

[Tony Brooks]

The Bukhs for canal use were normally sold with an Aquadrive so engine movement is not much of an issue. Is this a second hand or overhauled engine? If so I wonder if someone has mistimed the counter weights. If they are mistimed the movement will be worse.

 

I know the DV36 has different stiffness mounts front and back so if the DV24 is the same could you have mixed them up. I would imagine if they are misplaced diagonally the vibration would be a lot worse.

 

If you don't have and can not fit an Aquadrive/Pythondrive/long Centaflex coupling then I can't see why you should not solidly mount it AS LONG AS you get it properly aligned.

 

The mounts do not have a threaded stud, the engine sits on top of the steel insert with shims to align the engine to the shaft.

 

If its vibrations in neutral then I would suspect something out of balance or a too rigid exhaust pipe, if its when underway I would suspect shaft alignment as first options.

 

Cant say much else but Bukhs are normally very smooth.

[Neil2]

I had a DV24 for several years - if the engine "shakes" out of gear, at any speed, something is wrong with it. These engines are smooth as silk.  

 

As Tony says, in a narrowboat they are normally partnered with an Aquadrive, in fact I've never seen one rigid mounted to the shaft, - that's why they are sold with flexible mounts.  These mounts are very flexible though, so if you try and use the engine without a flexible coupling I would certainly expect a whole lotta shakin' goin on..  Even with perfect alignment.

 

I don't see why you shouldn't solid mount it, they are lifeboat/fishing boat engines after all, and I can't think they put Aquadrives in lifeboats.

 

Is it new or secondhand?  If it's new and it shakes out of gear go straight back to Nick/Steve, but I would be amazed.  If it's secondhand it could have been reconditioned and not correctly reassembled with the balance weights but to be honest Bukh engines are so well made there can't be many in the uk that have been rebuilt, though it could possibly have come from a fishing boat I suppose.  Final thought is the engine could just be goosed, Bukhs are made to keep on going regardless of condition or abuse so it's possible you could have a badly neglected engine with serious bearing wear.

 

 

 

 

 

[cass1]

The engine has come out of a lifeboat  bought from a firm in dorset I think they sourse them from india where they break ships  They check em out service and run them so they are supposedly good and low hours It starts straight away no smoke My thoughts on the vibes are because the original engine bearers were too far apart i extended the brackets  So the rubber mflex mount is about five inches from the block instead of about two  I suspect this may give the engine more flex than it needs  I will try solid mounts next

[Tony Brooks]

7 minutes ago, cass1 said:

The engine has come out of a lifeboat  bought from a firm in dorset I think they sourse them from india where they break ships  They check em out service and run them so they are supposedly good and low hours It starts straight away no smoke My thoughts on the vibes are because the original engine bearers were too far apart i extended the brackets  So the rubber mflex mount is about five inches from the block instead of about two  I suspect this may give the engine more flex than it needs  I will try solid mounts next

So enough room to bolts a couple of good bulks of hard wood to the inside of the engine beds to give you the proper mounting points.

[Bee]

Just a thought, Python / Aquadrives are dear things, I wonder whether a couple of universal joints would do the job just as well with a plummer block to keep things nice and straight.

[Neil2]

3 hours ago, cass1 said:

The engine has come out of a lifeboat  bought from a firm in dorset I think they sourse them from india where they break ships  They check em out service and run them so they are supposedly good and low hours It starts straight away no smoke My thoughts on the vibes are because the original engine bearers were too far apart i extended the brackets  So the rubber mflex mount is about five inches from the block instead of about two  I suspect this may give the engine more flex than it needs  I will try solid mounts next

Ah, I see, that wouldn't help however well balanced the engine was.

 

I've seen the advert for these engines, must admit my initial thought was too good to be true - given the price of a new unit.  But if it's a lifeboat engine it should have been hardly used - hopefully...

 

Did it come with a gearbox and is it the ZF marinegear - if so it's probably a better buy than a new engine which I believe has a much inferior box these days.

 

What does slightly concern me is that you say the engine doesn't smoke - it should, especially from cold.  It's the only downside of these engines that you can't totally eliminate the white smoke (unburnt fuel) unless it is running really hard under load.   

[mrsmelly]

13 hours ago, Bee said:

Just a thought, Python / Aquadrives are dear things, I wonder whether a couple of universal joints would do the job just as well with a plummer block to keep things nice and straight.

To be honest they are not so expensive these days and the beauty of them is that over time as the bearers wear and inevitably move even a fraction they stop undue wear on the shaft and alignment is of far less importance.

[Bee]

£700 from Midland Chandlers, probably better deals available. Incidentally the two CV joints in the Python /Aquadrives are listed at £369 but they are standard parts from various cars, they just pull off the shaft with a gentle (!) tap and are repairable by any number of specialists. We carry a spare joint, I think it cost about £40 from somewhere in Birmingham and should the original fly apart somewhere in the middle of nowhere I can feel incredibly smug.

[Neil2]

One good reason to buy the genuine article is to support guys like TW Marine who are experts in their field, hard working and give a lot of their time for free.  It's the same reason I buy my dog food in bulk from our local post office even though it is much cheaper from Pets at Home.  When folk moan about the lack of real shops on the high street or the demise of independent traders, this is where it starts.

 

In any case what you get from an Aquadrive is out of proportion to the initial outlay, I simply don't understand why all boats don't have them.  

 

 

[Tony Brooks]

32 minutes ago, Neil2 said:

One good reason to buy the genuine article is to support guys like TW Marine who are experts in their field, hard working and give a lot of their time for free.  It's the same reason I buy my dog food in bulk from our local post office even though it is much cheaper from Pets at Home.  When folk moan about the lack of real shops on the high street or the demise of independent traders, this is where it starts.

 

In any case what you get from an Aquadrive is out of proportion to the initial outlay, I simply don't understand why all boats don't have them. 

Me neither, but any two flexible element coupling plus thrust block will give similar benefits.

 

I agree firms like TWM deserve our support, very helpful and excellent service.

Edited May 16, 2020 by Tony Brooks

[Tracy D'arth]

1 hour ago, Bee said:

£700 from Midland Chandlers, probably better deals available. Incidentally the two CV joints in the Python /Aquadrives are listed at £369 but they are standard parts from various cars, they just pull off the shaft with a gentle (!) tap and are repairable by any number of specialists. We carry a spare joint, I think it cost about £40 from somewhere in Birmingham and should the original fly apart somewhere in the middle of nowhere I can feel incredibly smug.

As far as I can remember one joint is off a VW caravanette and the other a Porsche car but can'r think which one.

They are constant velocity joints, ordinary universal eg. Hardy Spicer joints are not, and will impart varying speed and torque into the shaft as they rotate.

[Tony Brooks]

50 minutes ago, Tracy D'arth said:

As far as I can remember one joint is off a VW caravanette and the other a Porsche car but can'r think which one.

They are constant velocity joints, ordinary universal eg. Hardy Spicer joints are not, and will impart varying speed and torque into the shaft as they rotate.

Only if they are not correctly aligned to each other or if each are driving through different angles. The variations will cancel each other out at the actual shaft.

 

I would not be overkeen to put prop thrust through hooks (spider) joints though so a thrust bearing would still be needed.

Edited May 16, 2020 by Tony Brooks

[Bee]

Its finding a thrust block and bearing that's the tricky bit, I reckon its much kinder to the gearbox to have the thrust taken by the hull but if the engine is moving around on rubber mounts you need to have a bit of fore and aft movement so the engine doesn't pull the innards out of the gearbox. Python / Aquadrives have this as the cv joints are on splines, same as cars and vehicle prop shafts to allow for suspension movement. Hardy Spicer joints have to be fitted at 180 degrees to each other (check that before you weld anything up solid!) Python/Aquadrives actually need a few degrees of angle on them apparently so they vary the wear on the internals so no more feeler gauges and shims. Hooray.

[Trevor Lyons]

Bruntons, who make the superb Autoprop, also make the SigmaDrive, an excellent device on the prop shaft to take account of misalignment and vibration. They say:

 

"What makes SigmaDrives different is their ability to resist propeller thrust when installed as a standalone coupling, directly from the shaft to the output flange on the engine’s transmission. It reduces and even eliminates vibrations that originate from an imperfect alignment between the propeller shaft and the engine, compensating for up to 3 degrees in all directions. This system can also be installed using thrust bearings so that the engine can be placed utilising the space available ergonomically.

SigmaDrives are designed to fit virtually all boats from yachts to workboats, canal narrow boats ... They are extremely easy to fit, requiring no modifications to the craft, which can usually be equipped with the drive unit whilst still in the water. Together with its anti-noise and vibration abilities having a SigmaDrive on your vessel also ensure that seals and bearings are always perfectly aligned, reducing wear and guaranteeing a longer trouble-free life for all associated components."

 

https://www.bruntonspropellers.com/sigmadrive

 

[Tony Brooks]

57 minutes ago, Trevor Lyons said:

Bruntons, who make the superb Autoprop, also make the SigmaDrive, an excellent device on the prop shaft to take account of misalignment and vibration. They say:

 

"What makes SigmaDrives different is their ability to resist propeller thrust when installed as a standalone coupling, directly from the shaft to the output flange on the engine’s transmission. It reduces and even eliminates vibrations that originate from an imperfect alignment between the propeller shaft and the engine, compensating for up to 3 degrees in all directions. This system can also be installed using thrust bearings so that the engine can be placed utilising the space available ergonomically.

 

SigmaDrives are designed to fit virtually all boats from yachts to workboats, canal narrow boats ... They are extremely easy to fit, requiring no modifications to the craft, which can usually be equipped with the drive unit whilst still in the water. Together with its anti-noise and vibration abilities having a SigmaDrive on your vessel also ensure that seals and bearings are always perfectly aligned, reducing wear and guaranteeing a longer trouble-free life for all associated components."

 

https://www.bruntonspropellers.com/sigmadrive

 

 

When I looked at the SigmaDrive at Crick it appeared to be a single element flexible coupling and a such it could not deal with radial misalignment as you would get when the engine shakes about. All the company rep would say is that it will deal with radial misalignment but was unable to explain how it did it. Basically its a single CV joint. Unless Brunton have rewritten the laws of physics I simply can not see how it in any way takes the place of an Aquadrive, Pythondrive or long Centaflex. If any engineers on here will look at their website and explain how It absorbs radial misalignment I would be very happy to know.

 

If you have a flexible stern gland like Vetus etc. AND a single Cutless rubber shaft bearing then in my view the SigmaDrive looks a far better prospect to avoid some vibrations than the 2maybe flexible" couplings like the R&D that is often used on such stern gear for inland use. My own feeling is that Bruntons probably know their original market very well where the norm tends to be a flexible stern gland and a Cutless shaft bearing bt they seem to have little idea about a typical narrowboat setup with a rigid stern gland and a plain metal bearing that allows all but zero play in the shaft. When I put this to them Brunton simply denied there was any potential problems with ridgid stern gear.

 

Take care and treat adverts and websites with a lot of scepticism.

 

I fear more copywriting be people who don't know engineering. Take this quote "compensating for up to 3 degrees in all directions". Note its not a technical statement because 3 degrees in all directions refers to what? Radial misalignment, angular misalignment, or both? Looking at their diagram I can only see it compensating for angular misalignment, not radial. So I think it very misleading

Edited May 16, 2020 by Tony Brooks

[Tracy D'arth]

4 hours ago, Bee said:

Its finding a thrust block and bearing that's the tricky bit, I reckon its much kinder to the gearbox to have the thrust taken by the hull but if the engine is moving around on rubber mounts you need to have a bit of fore and aft movement so the engine doesn't pull the innards out of the gearbox. Python / Aquadrives have this as the cv joints are on splines, same as cars and vehicle prop shafts to allow for suspension movement. Hardy Spicer joints have to be fitted at 180 degrees to each other (check that before you weld anything up solid!) Python/Aquadrives actually need a few degrees of angle on them apparently so they vary the wear on the internals so no more feeler gauges and shims. Hooray.

Its the splined stub that wears on Aquadrives, I tried to buy a new one, not available.  As I had a proper thrust bearing on the drive shaft albeit mounted on thin rubber bushes I locktighted it in the CV joins, no more slop.

Edited May 16, 2020 by Tracy D'arth

[Tony Brooks]

4 minutes ago, Tracy D'arth said:

Its the splined stub that wears on Aquadrives, I tried to buy a new one, not available.  As I had a proper thrust bearing on the drive shaft albeit mounted on thin rubber bushes I locktighted it in the CV joins, no more slop.

That's what Nick told me to do - was still OK when I sold the boat last september after 10 years or more.