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How noisy inside boat when engine running?


Pirateringo

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My first boat had an old knacker two cylinder Lister that resounded through the boat from its designated engine room. I learnt very quickly that after five years a nice modern watercooled engine under the ares end was the way to go. Ths boat, number 8 of our liveaboards has an isuzu and its Waaaaaaaaaay quieter than the Lister. If its in the back and you hear it 60 or more feet away in the front sommets wrong!!

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3 hours ago, Alan de Enfield said:

Take the other end and 'dab' it onto the engine mounts and all over the engine.

 

The engine could be out of balance if one cylinder is not firing

 

WATCH OUT AND STAY CLEAR OF ROTATING PARTS

 

You will feel the source of the vibration in your ear bones as soon as you get close to it.

This will deaden the noise almost completely. And all other noise.

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7 hours ago, mrsmelly said:

My first boat had an old knacker two cylinder Lister that resounded through the boat from its designated engine room. I learnt very quickly that after five years a nice modern watercooled engine under the ares end was the way to go. Ths boat, number 8 of our liveaboards has an isuzu and its Waaaaaaaaaay quieter than the Lister. If its in the back and you hear it 60 or more feet away in the front sommets wrong!!

Not only can you hear it at front but you cN also feel it vibrate

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9 hours ago, mrsmelly said:

My first boat had an old knacker two cylinder Lister that resounded through the boat from its designated engine room. I learnt very quickly that after five years a nice modern watercooled engine under the ares end was the way to go. Ths boat, number 8 of our liveaboards has an isuzu and its Waaaaaaaaaay quieter than the Lister. If its in the back and you hear it 60 or more feet away in the front sommets wrong!!

Not only can you hear it at front but you cN also feel it vibrate

I've managed to get a quick look at engine bay before work this morning. At some point the engine mounts have been changed as the footprint from the ones before was much larger almost twice the size of current mounts. I'm assuming the small ones are not big enough for size of engine? 

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33 minutes ago, Pirateringo said:

Not only can you hear it at front but you cN also feel it vibrate

I've managed to get a quick look at engine bay before work this morning. At some point the engine mounts have been changed as the footprint from the ones before was much larger almost twice the size of current mounts. I'm assuming the small ones are not big enough for size of engine? 

 

I think you may well be correct and unless the centre part of a mount has dropped and is hitting the engine bed I suspect its the shaft transmitting engine vibrations to the hull.

 

One "test" is to get help and set the engine speed to a bad vibration point and then get the helper to put their boot sole on a strong part of the engine ( not pipes etc.) and push really hard sideways. If the noise and more to the point vibrations reduce then its a fair bet its the mounts.

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https://youtu.be/buWveNYdTuo

This is a video from another member on here (hope you don't mind me linking it) 

Mine sounds very similar to this and the engine and stern gland etc are pretty much identical to this only difference I can see is someone has replaced the mountings with smaller ones at some point. Just to point out the vibration and noise comes in waves 

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Isuzu 42 with standard mounts and Python drive. Cant tell if the engine is running in the front cockpit. Noise inside the boat not excesive. However,the engine is water cooled by raw water passing through a heat exchanger. The water is then ejected through the exhaust, This is standard practice for seagoing boats and does quieten the exhaust a lot.

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But my 3 cylinder seems to be quieter and smoother than a lot of fours. Probably because it has an internal balance weight shaft. Still BIzzards idea is worth checking out. Easy to do just loosen and the re-tighten each injector large union in turn and see how much difference it makes to engine speed and movement.

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  • 3 weeks later...

Hi all, have only just had time today to have a proper look as I've been working away. 2 of the engine mounts rubber seems to have become a putty type substance I can literally take of blobs with my finger. I'm assuming this is the reason the vibration is so bad. The previous owner had a battery leak (explosion) I'm assuming this is too blame? Or is that just age? Any way the 2 bad ones are front right and rear left looking at engine from tiller. Is it an easy job to change. Please bide with me, I'm new to this ?

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7 minutes ago, Pirateringo said:

Hi all, have only just had time today to have a proper look as I've been working away. 2 of the engine mounts rubber seems to have become a putty type substance I can literally take of blobs with my finger. I'm assuming this is the reason the vibration is so bad. The previous owner had a battery leak (explosion) I'm assuming this is too blame? Or is that just age? Any way the 2 bad ones are front right and rear left looking at engine from tiller. Is it an easy job to change. Please bide with me, I'm new to this ?

Assuming you have no flexible shaft coupling or one with just one pint of flexibility your problem will be in realigning the engine to the shaft. You might also have to lift the engine several inches dependant on the mount design. For this one I would suggest pay and watch.

 

If you have a two point of flexibility coupling like an Aquadrive then apart from lifting the engaging no alignment is really needed

 

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8 minutes ago, Tony Brooks said:

Assuming you have no flexible shaft coupling or one with just one pint of flexibility your problem will be in realigning the engine to the shaft. You might also have to lift the engine several inches dependant on the mount design. For this one I would suggest pay and watch.

 

If you have a two point of flexibility coupling like an Aquadrive then apart from lifting the engaging no alignment is really needed

 

Thanks for the reply Tony, I have no idea if it's flexible or not. Is there a way to tell? I'm assuming I could just scissor Jack the engine up a bit and do one mount at a time? 

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1 minute ago, Pirateringo said:

Thanks for the reply Tony, I have no idea if it's flexible or not. Is there a way to tell? I'm assuming I could just scissor Jack the engine up a bit and do one mount at a time? 

Post a photo of what is between the gearbox and the stern gland

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2 minutes ago, Pirateringo said:

Thanks for the reply Tony, I have no idea if it's flexible or not. Is there a way to tell? I'm assuming I could just scissor Jack the engine up a bit and do one mount at a time? 

Its not changing the mounts its the realignment. The fact you do not know what type of shaft coupling you have convinces me my Pay & Watch comment is in your best interest.

 

Incidently it is not unusual to have different mounts front and back and they need matching to the engine.

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1 minute ago, Pirateringo said:

Thanks for the reply Tony, I have no idea if it's flexible or not. Is there a way to tell? I'm assuming I could just scissor Jack the engine up a bit and do one mount at a time? 

The point is that if there isn’t a flexible coupling then unless the engine is aligned to the prop shaft within a few thou the stern gland/bearing will not last long.  The new mounts are going to be a different height to the current mounts, so without the flexible coupling you must align the engine as part of changing the mounts.

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7 minutes ago, Tony Brooks said:

Its not changing the mounts its the realignment. The fact you do not know what type of shaft coupling you have convinces me my Pay & Watch comment is in your best interest.

 

Incidently it is not unusual to have different mounts front and back and they need matching to the engine.

LOL fair enough, cheers for the advice. I think I'll just get all 4 mounts replaced then 

Anybody know a person who could come out and do this for me? West Midlands area (lichfield) 

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1 hour ago, Pirateringo said:

LOL fair enough, cheers for the advice. I think I'll just get all 4 mounts replaced then 

Anybody know a person who could come out and do this for me? West Midlands area (lichfield) 

 

If you can get your boat to Streethay Wharf they will be able to do it.

 

I don't know if they would come out for this but I'm sure a phone call to them will establish this.

 

01543 414808

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