Bad Vibrations (from an alternator)

[system 4-50]

Whilst you are waiting for a mobile welding man or other fixer to turn up, is there any chance of providing more pics of the whole engine setup?  I am intrigued as to why anybody went to such extraordinary lengths to mount an alternator.  Is this arrangement standard for a Beta 43 of this period?

[Sir Nibble]

The mounting bolt at the bottom appears to have bottomed out on the threads. There's a gap at the front. When you reassemble replace it with two shorter bolts and tighten the pulley end one first. 

[GUMPY]

Beta can normally supply parts for all the engines they have made, give them a call they may well be able to supply a new mount. You will need the engine number as a reference.

[Alan de Enfield]

4 hours ago, system 4-50 said:

Whilst you are waiting for a mobile welding man or other fixer to turn up, is there any chance of providing more pics of the whole engine setup?  I am intrigued as to why anybody went to such extraordinary lengths to mount an alternator.  Is this arrangement standard for a Beta 43 of this period?

 

It seems odd to me that it has 6 (quoting the OP - 3 each side) engine mountings.

Never seen that before.

[Tony Brooks]

15 minutes ago, Alan de Enfield said:

 

It seems odd to me that it has 6 (quoting the OP - 3 each side) engine mountings.

Never seen that before.

 

Nothing to do with the OP's problem, but:

 

You are too young Alan.  At one time with huge mechanical gearboxes, a third set of mounts on a bracket between gearbox and reduction box was not unusual. But certainly odd for a Beta. I wonder if the OP is stalking about the bolts that holds Beta's length of angle iron engine foot  onto the block.

[Alan de Enfield]

1 minute ago, Tony Brooks said:

 

Nothing to do with the OP's problem, but:

 

You are too young Alan.  At one time with huge mechanical gearboxes, a third set of mounts on a bracket between gearbox and reduction box was not unusual. But certainly odd for a Beta. I wonder if the OP is stalking about the bolts that holds Beta's length of angle iron engine foot  onto the block.

 

Ha Ha - if only .........................

 

Being a boat that is 'from the late 90's' I wouldn't have thought it would have dated back " at one time ......."

[spicemouse]

Lots of great replies here, thanks!!

Here are some images that will hopefully clarify what's going on:

 

as you can see I've removed the alternator (and had to remove the stop solenoid too) and arm to make it easier for me to see what was going on.  

 

1 hour ago, Alan de Enfield said:

 

It seems odd to me that it has 6 (quoting the OP - 3 each side) engine mountings.

Never seen that before.

I was questioning if I should try and add a third set to reinforce the existing. There are only two.

 

 

here you can see which mount has gone. Thankfully not on the other side. 

 

Here is a much clearer image of the shear.

1 hour ago, Loddon said:

Beta can normally supply parts for all the engines they have made, give them a call they may well be able to supply a new mount. 

I assumed that this mounting system would be custom, I'll give Beta a call. I've got an account with them and they know the engine number etc.. 

 

FInally, can someone correct me on the plan as I understand it:

 

1) I'll need to get a jack under the engine, lift it up to the correct height

2) The top bolts on the mounting points will be removed and the bolts on the engine mounting points will be removed.

3) a new/repaired mount will be bolted back to the frame

4) then arm will be replaced and everything bolted back together. 

5) jack removed, I'll replace the alternator etc.. 

 

 

9 hours ago, Eeyore said:

Looks like the "best" way it could fail; loose bolts could have given a much bigger headache.

There are things in your photo that say this is not the first time that it's failed; no paint on the washers and what looks like a strengthening plate ( obscured by the dipstick tube).

You'll need to remove the top nuts from the new engine mounts and jack it up in order to get the engine mounting beam out.

The alternator mounting beam can probably be left attached as long as you disconnect and remove the alternator.

Make sure that the beam sits equally on the engine mounting points before you fit the bolts otherwise the whole thing will twist as you tighten the bolts, which is very likely to have be a contributing factor in the failure.

I've tried to follow what you suggested in the steps I've written. 

The you can see the silver paint on the mounting more clearly in today's pictures. 

[Alan de Enfield]

4 minutes ago, spicemouse said:

Here are some images that will hopefully clarify what's going on:

 

Yes, they make it much clearer.

 

It looks as if the engine has been installed quite recently, what is the history for that happening ?

[spicemouse]

7 minutes ago, Alan de Enfield said:

 

Yes, they make it much clearer.

 

It looks as if the engine has been installed quite recently, what is the history for that happening ?

 

The boat had a BMC when first converted from a working boat. At some point it was removed and the Beta 43 installed. Beta have dated the engine to 1997, but of course I don't know if it was new when installed. I've only owned the boat his year, and there is zero service history.  

Edit:

I should also add the mounting points on the wood support were replaced 2 months ago, which might be why it looks like a recent install. 

Edited June 26, 2021 by spicemouse

[Alan de Enfield]

11 minutes ago, spicemouse said:

I should also add the mounting points on the wood support were replaced 2 months ago, which might be why it looks like a recent install. 

 

Before you go spending money - I am just wondering who did the recent instalation and why.

 

There may be some comeback if the cracked mounting can be atributed to bad workmanship.

[spicemouse]

6 minutes ago, Alan de Enfield said:

There may be some comeback if the cracked mounting can be atributed to bad workmanship.

The engine was remounted by workshop at the brokerage, under condition of sale (paid for by previous owner). I can ask, but as I didn't pay for the work I doubt I'll get far. 

[Tony Brooks]

The mounts and engine feet should have an easy time of it with a hydraulic drive because they don't have to take prop thrust, so to me the question is why has the engine foot broken? I have no answer to that but a suspicion.

 

If you look at the length of stud sticking out of the top mount nuts in the last photo, it looks to me as if they are not equal. On a hydraulic boat, I would expect them to be, because there is no need to sit the engine at an angle to match the shaft. It may be an optical illusion but if I am correct then there is a good chance the engine weight was never evenly distributed front to back, side to side, and diagonally. This would stress on engine foot more than the rest, so that may be why it's broken. Uneven mounts will allow the engine to move about more than "normal".

 

However it is repaired, I would want to ensure the weight is equally distributed across the mounts to prevent it happening again.

 

With the front engine foot broken, the front of the engine would wave about, putting tension on and off the belt. That in itself might  cause the movement we see in the mounting bar.

 

I can see no reason it needs another pair of mounts as long as the existing ones are adjusted properly.

 

Note: Some engines use different mounts front and rear to allow for the weight of the gearbox or in this case the  hydraulics.

 

One of the photos suggest the hydraulic tank, pump, and valves may all be hung off the back of the engine and if so that may pull the back down so the front mounts are subject to little load, that may allow the engine to wave about at the front more than usual.

 

[spicemouse]

12 minutes ago, Tony Brooks said:

One of the photos suggest the hydraulic tank, pump, and valves may all be hung off the back of the engine and if so that may pull the back down so the front mounts are subject to little load, that may allow the engine to wave about at the front more than usual.

 

The whole tank/pump setup hangs off the back of the mounts. You'd think this would reduce the load on the front, but many this uneven loading allows more vibration? 

 

21 minutes ago, Tony Brooks said:

If you look at the length of stud sticking out of the top mount nuts in the last photo, it looks to me as if they are not equal. On a hydraulic boat, I would expect them to be, because there is no need to sit the engine at an angle to match the shaft. It may be an optical illusion but if I am correct then there is a good chance the engine weight was never evenly distributed front to back, side to side, and diagonally. This would stress on engine foot more than the rest, so that may be why it's broken. Uneven mounts will allow the engine to move about more than "normal".

These? 

[Alan de Enfield]

 

The 'piece of wood' underneath the engine mounts looks to me to be a cork floor tile.

[spicemouse]

9 minutes ago, Alan de Enfield said:

 

The 'piece of wood' underneath the engine mounts looks to me to be a cork floor tile.

Haha, you actually made me go and check! 

Steel plate thankfully. They were added to allow more mounting points to the wood. 

[Alan de Enfield]

4 minutes ago, spicemouse said:

Steel plate thankfully. They were added to allow more mounting points to the wood.

 

 

Phew ............

 

From the top view they looked very much like the cork tiles we had in the boat galley.

[Tony Brooks]

14 minutes ago, spicemouse said:

The whole tank/pump setup hangs off the back of the mounts. You'd think this would reduce the load on the front, but many this uneven loading allows more vibration? 

 

These? 

 

Yes, circled areas in bottom photo

 

I was thinking more about uneven side to side or diagonally and yes it may allow more vibration.

 

As long as it did not allow something to  foul something like the sump on the baseplate I would simply screw the lower nuts on each mount right down so you know they are all the same height and there is less leverage on the rubber in the mounts.

 

I am also struggling to see the purpose of the wood/cork on a flexibly mounted engine system. Good practice for solid mounted engines but not flexible ones. Seems it might be a body way of packing the mounts up.

 

Please don't take my thoughts a gospel. I would prefer other of our engineer members to give their opinions.

[David Mack]

23 minutes ago, spicemouse said:

The whole tank/pump setup hangs off the back of the mounts. You'd think this would reduce the load on the front, but many this uneven loading allows more vibration? 

With all that gubbins hung off the back of the engine it would be better if that angle iron was longer, extending further back, allowing the rear flexible mounts to be set further back, to give better load distribution between the four mountings.

[Tony Brooks]

11 minutes ago, David Mack said:

With all that gubbins hung off the back of the engine it would be better if that angle iron was longer, extending further back, allowing the rear flexible mounts to be set further back, to give better load distribution between the four mountings.

 

I think that would be the easiest fix apart from that hydraulic connection right in the way but I am unsure as to how relevant it is to the broken foot. Engine feet do not normally just break, something causes it.

[spicemouse]

The fix I'll be trying for will be:

 

1) I'll need to get a jack under the engine, lift it up to the correct height

2) The top bolts on the mounting points will be removed and the bolts on the engine mounting points will be removed.

3) a new/repaired mount will be bolted back to the frame

4) then arm will be replaced and everything bolted back together. 

5) jack removed, I'll replace the alternator etc.. 

 

Ideally I'd have the wood removed and the engine mounted directly to the hull. But I'm afraid I think I'll be doing well to just get moving again. 

[Bee]

You might not need a jack, I have had to alter engine height and all sorts of fiddly jobs and an old pickaxe handle will lever the thing up and down quite easily, a heap of wedges, offcuts and bits of firewood will keep it dangerously poised at the required height whilst you risk your fingers.

[Alan de Enfield]

51 minutes ago, spicemouse said:

 I'll need to get a jack under the engine, lift it up to the correct height

 

Make sure you put a large piece of wood / metal underneath the jack to spread the load. If you try and lift "a tonne" of engine on a couple of square inches of the foot print of the typical jack, if the bottom is not 'in the first flush of youth' you could go straight thru the bottom of the boat.

[Chris Lowe]

The edge on that crack loocks fairly clean and shiny, no corrosion so it would seem to point to a recent break.

[Tony Brooks]

55 minutes ago, Alan de Enfield said:

 

Make sure you put a large piece of wood / metal underneath the jack to spread the load. If you try and lift "a tonne" of engine on a couple of square inches of the foot print of the typical jack, if the bottom is not 'in the first flush of youth' you could go straight thru the bottom of the boat.

 

I would be more concerned abut the sump, so two large pieces.

[Eeyore]

Here's something to read

http://www.randdmarine.com/downloads/RandD_Engine.pdf

The dry weight of the engine is about 180kg, so about 200kg with alternator, oil, coolant and other items added by Beta.

Take the opportunity to estimate the centre of gravity of the assembly whilst you have the jack under it. The rough position for the centre of gravity of the engine alone is somewhere in the area of number three cylinder; so a lot closer to the flywheel housing with the hydraulics hanging off the back.

Extending the engine mounting beam, as David Mack says, can only help; but I doubt you get sufficient length to achieve perfect balance.