Jammed deck on 420 mower. Now wont engage properly?

[MilesToEmpty]

Boy did I hit a winner on this.

Just got our 86 Deere 420 (newer Onan) lawn tractor running and I go and hit a solid 4x4x8" piece of pressure treated lumber.

I clipped it on the left side of the mower deck, and it jammed the deck instantly. The mower coughed and sputtered and as I was trying to recover, it died before I could disengage the PTO.

I drove it back to the garage and was able to pop the wood out with ease. Blade turned freely, no damage visible anywhere. Turn the blades and the 3 pulleys on the front of the engine would turn. If you grab the belt you can turn the pulleys and the blades with ease. So i know nothing is jammed or bent.

When you flick the PTO on now, it sounds almost like a steam engine chugging off, and the mower is very slow to, I guess you can say, fully engage.

Forget turning it on at anything other then idle... Just makes the puffing noises and it either does nothing (light always comes on) or starts spinning about 2x as fast as the second hand on a clock. It may or may not start up.

Before we would get a hiss and the thing would just engage, and run like a bat out of ****.

My question is, what happened when the crank was trying to power that PTO.

I have brand new belts and an idler pulley (not the issue since nothing up front really spins)

And the next thing... all the parts Im finding for this thing only show one belt up front. Ours uses 2. Am I just looking at the wrong information?

Thanks!

 

[IcUdoUcme]

Have you taken the mower deck off and checked to see if the pto shaft spins freely by hand?

 

[beenthere]

Which mower deck do you have.

Belt driven deck (you mention two up front) ?

More info needed here. Sorry to hear of the problem. Maybe something sheared loose.

 

[beenthere]

I found a 420 lawn&garden Deere with two drive belts for the PTO, that run off a PTO gearcase (shown here). If so, possibly the gears in the gearcase (hope not) where you should look.
Remove the deck as ICU said, and try to engage the PTO to see if the noise is in that gearcase (if that is what you have).

 

[MilesToEmpty]

Have you taken the mower deck off and checked to see if the pto shaft spins freely by hand?

Which mower deck do you have.

Belt driven deck (you mention two up front) ?

More info needed here. Sorry to hear of the problem. Maybe something sheared loose.

The PTO will spin if you attemp to turn it. There are 2 belts on the front of the engine. The Pulley config is:
.......engine
..idler
.......pto

The PTO is of course shaft driven to the mower deck.

If you spin the PTO shaft by hand, you can see the blades and belts ON the deck spin, as well as the belts/pulleys on the front of the mower.

 

[beenthere]

So Miles, you don't think you have that gearcase behind the double belts driving the PTO shaft?
From the parts manual, it is hard to decipher what is on the engine side of these double belts (shown here)

Maybe that gearbox previously shown is just for 540 RPM shaft on the front of the 420 tractor. And this pic of the double belts is a pulley direct off the engine.
With the deck off, what does engaging the PTO sound like? Normal?

 

[IcUdoUcme]

Sorry I ment spin the pto (male end) on the rider. It should spin freely if you turn it to the left (counter clockwise) it will normal make clicking noises like a ratchet. When you spin it feel it to see if you have any vibrations or any inconsistencies in sound or feel. If you can spin it clock wise and counter clockwise pretty freely some gears got stripped or something broke. you shouldn't be able to spin it clockwise by hand. If you can something broke. If you diconnect the mowing deck pto shaft from the riders pto and engage the pto does it sound normal like it used to, or does it sound worse? Do you feel any vibrations?

I had done the exact same thing you did with JD445 ride on mower. as soon I as brought it back to my garage I took the deck off removed the belt and checked the blade shaft. I over spun one bolt holding on the blade and bent that blade. I also damaged the gear case on the mower deck.. Anyways my point is try isolating the deck from the power source. If the power source is the problem(PTO) you can better diagnose the problem.



This will also allow you to check your blades to make sure they didn't bend or crack.

 

[MilesToEmpty]

I feel as the the main clutch providing the PTO is the problem here.

When you flip the switch to turn the deck on, Im assuming the engine crank pulley engages somehow, which powers the pulley for the PTO gearbox/shaft/etc.

When you flip the switch, barely anything at all happens. The whole belt assembly start to turn ever so slowly.

I feel like if I took the belts off, the engine pulley would just spin freely, but not at proper speed.

I should also add in, that we are still able to use the mower. It doesnt have that 420 power, maybe almost as much power as my honda push mower to the deck. If gearbox was damaged, we'd be SOL.

Sometimes once the deck fully spins up you hear the clutch fully click on.

 

[MilesToEmpty]

So Miles, you don't think you have that gearcase behind the double belts driving the PTO shaft?
From the parts manual, it is hard to decipher what is on the engine side of these double belts (shown here)

Maybe that gearbox previously shown is just for 540 RPM shaft on the front of the 420 tractor. And this pic of the double belts is a pulley direct off the engine.
With the deck off, what does engaging the PTO sound like? Normal?

Thats the diagram for the idler and PTO. I think I need a breakaway for the pulley on the engine itself.

 

[zzvyb6]

Remove all of the blades, I'll bet one is bent and the resulting imbalance is causing a vibration problem. All the blades should nestle together when stack on top of each other.

Or, you bent a spindle...