Rod_N

Many thanks for those helpful replies. I think I understand it now. Cheers!

Hi, I have a stern gland shown below which is assembled using rings rather than the more usual nuts and bolts. There are two rings (moved with a C-spanner). In the attached picture the top ring is nearer to the propeller. I need to know which ring do I adjust when too much water is coming in, and how do I dismantle it to re-pack it? Normally I would just try it and see, but I am aware that a mistake here could end up with a sunken boat! Any advice on this would be gratefully received.

Yesterday I obtained the new alternator belts from a nearby chandlery, and successfully managed to change the belts! I needed a good torch to see what I was doing. For reference, the belts are SPA-882 for the left-hand belt (driving the water pump and left-hand alternator), and the right-hand belt is an SPA-975. These are not Isuzu belts, but as I understand that Isuzu no longer make these engines, Isuzu belts may be hard to source. To change them, I had to sit astride the engine and lean well forward, until I could feel the pully wheels and the ends of the nuts which attach the alternators. Fortunately it was not too difficult to get the new belts on, and I ran the engine without problems for several minutes after fitting the belts and tightening everything up. On reflection, I would definitely change the belts myself again if required! Thanks again for the suggestions and comments posted here.

I think that would be a job where I would get a professional in!

Unfortunately it would mean cutting into a main bulkhead, so I don't think I will go for that! I've now managed to get the old belts off and order new ones. I can put my hands round the front and feel all the wheels and grooves, so I shouldnt have any problem putting the new belts on as long as they are not too tight.

Thanks for all the replies so far. So far I have discovered (confimed above) that each alternator pivots about a bolt which requires a 6 mm allen key at the rear, where I can see it, and a 13 mm spanner on the head (where I can't see it). THere is also a nut and bolt which passes through a slider which holds the alternator in the chosen position. I've managed to loosen the left-hand alternator, but the right-hand one is done up so tight I haven't been able to loosen it, even with lots of WD40 applied! I'm going to try to get some sort of socket with a 6 mm hex end as my allen key is not long enough to apply sufficient leverage. Possibly a longer 13 mm spanner will help as well.

The stern decking is removable, but the opening created stops about a foot or so short of the front of the engine. So although I can get in to the engine compartment, I can't see round the front of the engine, where the belts are located.

Hi, my first post to this forum as a narrowboat owner for just a few months! I need the two alternator belts on my Isuzu 42 hp diesel engine. The belts can't really be seen as they are at the front of the engine under the stern decking so it will have to be done more or less by feel. Can anyone tell me whether it is a straightforward job or not? So often I find there are unexpected difficulties when doing a job for the first time, with a worst case scenario of ending up with a boat that no longer works! Also are any special tools needed?