Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

   How does the belt drive pulley on a Poulan rear engine rider model WELRV1 come off?

   The parts list shows a 1 piece pulley attached by a bolt in the usual way in the center of the crank end.  This one seems
to have a one piece collar with 1/2 of a pulley on the end.  The other half of the pulley is also the drive plate for a
friction disk.  [This thing has a drive section just like a snowblower.]

   There was no allen set screws in the collar part. 

   There were three bolts on the inside part of the pulley which screw into the other half, the drive plate part.  I assumed
with the screws out the drive half would come off.  It would not. 

   The drive half is fairly thick so I tried tapping from the back with a brass hammer but it would not budge. 
I tried a couple of pickle forks and no movement.  I heated it up and hammered in the pickle forks with stiff blows. 
It still would not budge. 

   This thing has me puzzled.  Since the collar does not have allen screws what holds it on?  On the collar part of
the pulley there's an impression on the outside like for a key.  But since it's on the outside there's nothing that
goes over that slot or could mate to it. 

   What's up with this pulley?  How does it stay on and how does it come off?
  
   This machine if only a few years old and had been garaged so no rust and looks like new.  The drive plate
looks funky but that's due to the heat applied.  There's no rust on this machine and I don't think the pulley sections
are rust frozen.

   [The engine is hosed and I'm taking it apart to see what happened.  The cam went for some reason and in a
weird way.  When the fly is turned to work the valves (Briggs 8.75hp OHV) the two valve rods move together.  That is
they open the valves at the same time, then close them so no intake exhaust action.  One valve also clicks with 1/16
inch jumps.  I don't see how a messed up cam could work the valves like that so opening it up to see why?  The
flywheel will only go in one direction but the rod seems fine moving the piston up and down at it should. 
   The engine had issues and I fixed those then took it for a test drive.  It ran for about 15 minutes then stopped without
any noises and developed the valve issue. ??]
 

   This is the machine.  The engine is a Briggs 8.75 engine.
   

   This is the engine.  The combination pulley and drive plate are mounted to the engine crank.  The engine mounts in back of
the rider on the frame and the shaft end with the combination pulley stick into the drive section of the mower.
    The pulley drives the belt and the outside half of the pulley acts as the drive plate for the friction disk.  The drive plate
drives a friction disk just like a snowblower and off the friction disk axle chains that drive the wheel axle.


  This section of the pulley has three holes.  Three short bolts go those holes and screw into the drive plate part of
the pullet.   If you look close you can see the holes. 
   There is also a key like slot on the collar which is a puzzle.  There is nothing to go into the slot so I'm not sure what
it was put there for. 
   Since the screws hold on the drive plate half it seems like it should come right off.  Just how to get the collar and pulley
part of is a puzzle. 



   The valve action is very weird i.e. both rising at the same time and never individually, plus one clicks.

    I got this fee as it smoked and the guy could not start it after it smoked.   The sump was loaded with oil and gas.  The
valves were way off so that probably let in the gas.  Those were reset.  The spark was too low to start the engine so a
new coil fixed that.  I put in new oil and it fired right up and ran well.  I drove it around for about 15 minutes then it stopped
running.  There were no noises like something broke it just stopped. 

   I figured a valve may have slipped it settings so tried to adjust the valves.  When I did that and rotated the flywheel
to get the piston at TDC the valves moved together and one clicked.  I could rotate the flywheel only in one direction so
something in there is wedged.  I can't figure out how the cam is making the valves move together.  It's obviously
turning but the lobes are are different places on the cam shaft so the rods can't be moved together by the lobes.  It's
very odd so the reason for cracking open the engine to see how this could happen. 

I think that the cap in the middle needs to be removed and you will find a bolt holding it on.

jrtrebor & ajallen,
   What both of you have said makes sense.  That the key like indentation in the collar probably extends into
a slot on the crank.   That the end part of crank in the drive plate section of the is probably a cap.  Then the
bolt holds the combined halfs of the pulley on.

   I had called Poulan support and got nowhere the first time and refered to local dealers.  I went to three
this afternoon and none had ever seen this arrangement before.  I called Poulan to see if I could get
to an engineer but the support guy was savvy and a great help.  He assumed as ajallen mentioned that
the cap was a press fit and a bearing behind it then a bolt that holds everything on.  When the bolt is in
the three screws on the inner pulley half will hold on the pulley drive plate.

   The reason for the cap we were fuzzy on but now I realized what it's for.  The drive plate drives the
friction disk and the friction disk at low speed will be in the inner section of the drive plate.  The drive
plate turns and if there was no cap the friction disk would ride on the edge of the hole in the center
of the friction disk. So the cap is to prevent that. 
    It should also turn so the friction disk won't burn up.  They put a bearing behind the cap so the cap
can turn..  The cap must pressed into the bearing and the bearing press into the hole in the drive
plate.  That all makes sense.

   Just how to get the cap out is a mystery.  Boston Lawnmower is one of the better dealers loaded
with good mechanics.  We figured it was a cap so he tried to get it out by hammering with a very
small punch.  Some of the other guys there gave some opinions but the cap would not come out.

    I'm going to try to grind it out.  The bearing is probably a very tight fit and the cap a tight fit into
the bearing (ball bearing) so it can turn but stay in. 



31 is called a neutral spacer which through me off.
30 is the ball bearing.

  Now that I think about the neutral part of the description maybe that name is from the center being "neutral".  That is
one side of the friction disk is forward and the other reverse.  Neutral is the center.  I'm not sure how this thing works
but maybe the friction disk is aways turning.  ??

So I think grinding out the neutral spacer and ball bearing will give me access to the bolt and I'll be able to get the engine apart.

jrtebor:
>>The cam lobes are usually cast as part of the shaft so they can't spin change where they are on the shaft.
   Right, and their at different places to time the lifting of the rods.  Both can't lift at the same time.  The drawing
shows a single piece part so no slip on lobes to shift.  There must be something attached to the cam shaft
to cause the lifting.  ??

>>Do the rockers look like the are in the right place and position?
   The rockers are in the right place.  One end over the rods and the other on the valve spring cap ends. 
  

    So it was a cap, rollerbearing and under that the bolt which held on the pulley. 

    All in all a somewhat clever design if you leave out trying to repair this arrangement.   Poulin made the, not MTD.
Poulin's customer support does not know about this design so does not know how to deal with it or give customers
advice.  Taking this off or replacing a pulley is not in their service manual per the Poulin service department.  Neither
them or their field service dealers know how to deal with this design (three dealers here in eastern Mass). 

   This half of the pulley is the inside view.  The three holes are for attaching this half to the half that goes on the
crank shaft.  That half has the other half of the pulley and a keyed collar for the slot in the crank.  The bottom crank
bolt holds it all together. 

   The middle boss is to make room for the roller bearing and cap.  The other side is flat and the friction disk side.



   The next two are of the hole for the bearing and cap.  From what I could tell the bearing is in there with so tight a fit
that it would be impossible to get out.  

jrtrebor,
   I'm not sure about the way to get it out with saving the part.  The top cover is mated to the bearing and I'm not sure
if it could be pulled out by screwing something in there.  You'd probably destroy the cap in the process.  Same with
welding.   What you suggest may be cleaner than what I did which was use a Dremel tool with a diamond disk. 
There's still a lot left in there that maybe can be cleaned up but very time consuming already.

For the cam part I've started a new thread.