Blade engage pulling down engine.

[Wynnsman 8]

I have a 1257, I just replaced a pulley bearing the last time I mowed it didn't bog down at all. I mowed last night and could barely mow for the engine bogging. This has happened a few times in the past but last night was bad. The blades move freely and everything look and moves easy. Any suggestions?

[dsholler 54]

Not sure of the setup on that tractor, but any friction on the belt path will cause my 414 to bog down a bit. I accidentally lost one of the spacers on the mule drive, so the belt was rubbing on the edge of the cover. Not enough to make serious noise, but the engine bogged down noticeably. Check the whole run for friction...

Also, I think it is possible that if something is wrong with the deck, it could have a different geometry when hung on the tractor vs sitting on the ground. I would make sure it is spinning freely when it is in the mowing position... mine definitely flexes a bit when I lift it.

 

If it is not that, then I would start suspecting the engine is not putting out full power for some reason. I assume you are running at full throttle.

[Wynnsman 8]

Yes very much full throttle. I will check the belt. It's the same deck that's been on for 40 years so I don't think it's the deck. The belt friction may be the issue. Thanks!

[dsholler 54]

The reason I mentioned the deck is that there have been a lot of other reports on this forum of the decks getting bent or cracked from being banged into stuff. Not that any of us would ever hit anything with the deck of course   Mine must have hit something, because if I raise it to the travel position and spin the deck, one of the blades grazes a bold head on the underside, which it does not do when in mowing position or upside down.  If yours is doing the same, there might be friction on the deck belt that does not exist when you have it off the tractor.