Belt tightness on mower decks

[msjanket]

My 42" deck received a new belt. How tight does it need to be adjusted? Do I measure spring length on the tightening pulley? I had some smoke come out of the compartment where the belt is located, is my belt too tight or too loose? The bottleneck appears to be around the idler pulley on these types of mower decks, the belt goes from the drive pulley to the idler pulley in a short space and I wonder if I am generating too much heat from this area where the belt changes direction in a very small distance.

[J_J]

Check your idler bearing.

Spin each blade with belt off to check bearings.

Do you have alignment correct?

Is that a factory spring on the belt tension pulley?