John Deere 175 Hydro 38" deck - throwing deck belt

[dragon73]

I have a John Deere 175 Hydro with a 38" deck. The belt that is on the deck keeps jumping off at the tensioner. Today, i finished putting new bearings in both blade spindles, the drive pulley, and idler/tensioner pulley (pulley and bearing were one unit). After assembling everything making sure it was together properly using the exploded parts diagram, I noticed that the Pulleys were all on a different plane. The blade pulley is the lowest, then the idler pulley, and the drive pulley is the highest. Also, there is a tilt to the drive pulley and I don't know if this is correct. The plane of the idler pulley and the blade pulley are parallel The deck looks like it's in good shape with no dents or bends to it that would cause the pulleys to misalign. Is this correct or is there something wrong? Here is a picture of it.

 

[tomplum]

That is a heavy made deck, but a lot can happen in 20 years. I assume that you also replaced the bushings on the stack pulley arm. These are not really known to toss belts. You have to start somewhere. Being concerned with the pulley alignment, start with the spindles and bring the rest as near as you can into alignment. Start with a new OEM belt and replace the tension spring if there is a question.

 

[dragon73]

No, I didn't replace the bushings. They were as tight as can be - zero play. When I took it all apart, it had obviously been rebuilt not too long ago. I had been using it just fine for a quite a while and then all of the sudden it started throwing belts. There was a little play in the bearings, but not much. The local lawn and garden place told me to replace them so that is what I did.

Should the pulleys all be in the same plane? I can't really see how they would be because the stack pulley can't go much lower and I know that I put the blade assembly back together properly. Everything is very heavy made like you said and nothing looks bent. The tilt of the stack pulley concerns me but again nothing looks bent. I can shim things up so that the pulleys are in alignment if that is what it needs. Just don't know what it was originally like.

 

[tomplum]

It isn't uncommon to see fixed tension pulleys askew to make the transition from the last spindle to the engine pulley. The real question - does the housing show ANY deflection at that bracket or spindle? The stack pulley should run straight with the spindle pulleys.

 

[Jimmy Joe]

Did you put a new belt on at the same time? If so was it a deere belt I would try a new one of those also wherever the idler or drive pulleys pivot there is sometimes a plastic bushing to replace check that. Sometimes once a belt throws it gets sort of a memory where it naturally wants to twist and derail.