Noisy Prop when Gear Engaged

[TheSaintlyOne]

So the BMC 1.5 on my new 48ft Narrowboat Project is running well apart from a little issue with a loose coolant hose now replaced. But the prop shaft when engaged makes a loud noise. Like a constant grinding sound I thought the engine was just really loud when moving until I had to pass another fellow boater and engaged neutral and the BMC sounded like a typlical diesel transit. Any ideas what the noise might be and the best way to rectify it. 

[Boater Sam]

Clarify please. Is the noise there whenever the prop shaft is turning? Or only when the gear is engaged? Same in reverse?

Which gearbox? Is the engine quiet when out of gear?

Are the engine mountings collapsing letting the engine or gearbox touch the steelwork?

Do you have a thrust bearing on the prop shaft or is there nothing between the gearbox output flange and the stern gland?

[TheSaintlyOne]

1 hour ago, Boater Sam said:

Clarify please. Is the noise there whenever the prop shaft is turning? Or only when the gear is engaged? Same in reverse?

Which gearbox? Is the engine quiet when out of gear?

Are the engine mountings collapsing letting the engine or gearbox touch the steelwork?

Do you have a thrust bearing on the prop shaft or is there nothing between the gearbox output flange and the stern gland?

The noise is only present when engaged, in neutral it sound like I guess it should, well similar to my diesel transit connect.. same in reverse. Not sure on the gearbox make 

 

Not sure about the rest tbf

 

I posted a vid of the boat on my Facebook below that is the sound!!!

 

https://m.facebook.com/story.php?story_fbid=10163141063840389&id=621550388

[Tony Brooks]

28 minutes ago, TheSaintlyOne said:

The noise is only present when engaged, in neutral it sound like I guess it should, well similar to my diesel transit connect.. same in reverse. Not sure on the gearbox make 

 

Not sure about the rest tbf

 

I posted a vid of the boat on my Facebook below that is the sound!!!

 

https://m.facebook.com/story.php?story_fbid=10163141063840389&id=621550388

 

Well, how about a photo. At present we can only guess .

 

I can hear a roar but that could just as much be intake or exhaust roar rather than  the gearbox.

 

Use a listening stick between various non-moving parts and your ear to try to localise the noise.

 

If you think a 1940s designed 1.5 is going to sound much like your computer designed Transit then I fear you will be disappointed.

 

From what I can hear I doubt its a drive plate breaking up but might be collapsed engine mounts or an out of alignment engine allowing the shaft to press hard against the stern gear or the engine/gearbox to press hard against the hull. If thsi is an original Tempest/Newage 1.5 then the rear mounts that are now unobtainable did have a habit of collapsing so one or more bolt heads sat on the engine bed. Again photos.

 

If you have a very old sun & planet gear type gearbox they will be noisy in reverse and if bearings have gone in ahead as well.