Mower deck Husqvarna Z254 - belt shakes very badly and engine tries to die when blades engaged

This is for a 2015 model - always run pretty well, but last year there was a lot of vibration when the blades were engaged - you can see the belt vibrating a lot, especially on the left side.

The belt had a few chunks missing and looked pretty worn so I went ahead and replaced it this weekend. The vibration is still really bad and now whenever I engage the blades it seems like the engine bogs down and almost dies - it picks right back up, but the belt seems pretty violent.

I'm really not sure what the next step would be - any advice on what to check/try next?

Thanks!

Take the belt off and either remove the deck or get the mower high enough to get under the deck.
Grab each end of each blade, try to move it up & down the rock from side to side see-saw style.
Any movement = time for new bearings.
spin each one and check for smooth quiet rotation.
Again any rumbles or jerkieness = new bearings.
Have a close look at the blades
Any lumps missing, any splits or bends where they should not be = new blades + new bearings
Check the spindle housing where they bolt to the deck.
While the 4 bolt ones are a lot stronger than the old 3 bolt ones the lugs still crack or break off.

Now on top of the deck check the tensioning arm for a free smooth movement.
Check the pivot on the tension arm as it tends to wear oval.

Spin both idler pulleys again checking for smooth quiet movement .
Again any failure = replacement of the whole pulley as the bearings are captive.
Check all of the pulleys ( including the engine pulley ) for something stuck in the groove.
Tree nuts get in there and can be near impossible to remove.
While you are checking the pulleys for debris also check the flanges for dents.

Just put on new blades, so can at least remove that from the equation. I bought a mower lift to make maintenance a little easier so I will check this stuff out this weekend - or try. Not sure on this thing what should move with what amount of force.

I should also ask if the belt keeper/guide could cause a problem? At one point a couple of years ago I loosened the bolt holding that and didn't know what position it should be in - always meant to go to Lowes and take a picture of what it should look like, but pretty sure it isn't in the right spot. I had an issue around this time where the belt kept shooting itself off.

If the guide has deep wear in it then it is in the wrong position.
If the belt is on the wrong side of a guide then it will do what you describe but with lots of smoke & a burned belt.

Pulleys on the spindles can also be worn in the center hole. Check that too.

If you look at the idler tension arm on the deck there may be a hole between the two idler pulleys . If so the end of the belt guide should drop into that hole and then tighten the the nut on top of the idler pulley that holds it. Also that belt guide should face straight up and down with no angle to it. It is not uncommon for the belt to grab that guide and put a nice twist into the guide rod.

If I posted a picture, would it be possible to tell if the position is correct?

Belt guide should be straight between the two idler pulleys, in line with that square hole in the arm. May even drop into that hole.

ILENGINE said:

Belt guide should be straight between the two idler pulleys, in line with that square hole in the arm. May even drop into that hole.

Click to expand...

Up too high to fit in there. As much as I try, I cannot unloosen the bolt holding that thing on - tried both directions and barely get any movement - probably why it ended up being in that position.

Okay, so it seems they don't sell this at the Lowes around me anymore - replaced with Craftsman.

Took the belt back off and tested the blades - no wobble, but I did notice that while the center blade spins freely, the left side has a little resistance and the right has a ton, as well as being bent very slightly (see picture). I hit a tree stump last year and the blade tore through part of the deck, must have happened then.



Does the whole assembly have to be replace? I tried to remove the top part (see picture), but I'm not sure what is safe to hold onto to remove the nut.



Without the belt there is zero hesitation when the blades are engaged, so at least it isn't related to the main spinner. I know, my technical terms are great.

Edit - So, finally removed it. Not sure if it happened now or earlier, but the mandrel broke off two of the bolt holders. Pretty sure the spindle that sits on top also made its own new grooves as I had to use a hammer to remove it. Ordered all new parts and fingers crossed that is all. Afraid to remove the other two in case they crack.