Yanmar 4JE - alternator belt replacement

[Caladh]

Was it really that difficult ? Helped a friend do this yesterday. We had to remove the whole caboodle to do the job. There appears to be no way to adequately adjust the belt Oror even remove the belt) becuase the alternator housing mates up with one of the large fresh water pipes. I'd hate to have to replace it in anger at sea.

We then went on and changed the impeller which went ok other than the Yanmar owners book shows a picture of the the water pump and direction of fin-travel but it is in fact upside down !! I mean how easy can it be.....

 

[pissativlypossed]

The easy (?) way is to remove the pulley on the engine block and fit the belt onto the pulley then refit the pulley, it isn't exactly easy or straightforward but that's how the manual tells you to do it. I tried for hours to fit it without following the instruction. Impossible!
Keep the old belt, I found that mine had worn sufficiently to be refitted without following the above procedure, should be OK in an emergency.

 

[Mistroma]

I found it easy to remove & refit on my Yanamar 4JH4AE. It can be tight when the belt is new and I revert to splitting the pulley as described in the manual. Only 4 bolts so not difficult. Once it has stretched it isn't difficult to remove or replace without splitting the pulley. I've only used 3 genuine belts so far and no signs of wear, but replace every 2-3 years and keep old one as spare.

 

[RichardS]

Fitted a new Yanmar belt on my 3YM30 recently and that was also incredibly tight so used a car engine technique of a screwdriver as a level on the belt against the water pump pulley whilst a helper turns the engine over with a spanner on the crankshaft pulley. As the screwdriver goes over the pulley the belt slips off the screwdriver and onto the pulley.

Richard