It sounds like you may have routed the belt around the outside of a belt guide. With the engine OFF, engage the blade and see if the belt is rubbing against something it shouldn't. Also check any belt guides for discoloration (bluing).

Thanks...I'll check that out. With the engine OFF, should the blade rotate freely or should there be some friction?

I'll let you know what I find.

Don't you have an owners manual to show the belt routing?
If you go to the Sears website at the link and enter your model# (probably 917.xxxxx or similar), it MIGHT show a link to the right to download one.

Here is a link that might be useful: Sears parts

what do you mean by "oil disappears" ? Belt over a guide probably ?

Remember, the vee side of the belt goes into the vee pulleys, and the flat, back, side of the belt runs on the flat pulleys. Also, as some have said, be sure the belts are inside of the belt guides. (Those long things hanging down that look like bolts without nuts!)
Looking down at the engine and deck, be sure the deck belt is turning the same way as the engine rotation. Engine turns to the right, deck belt does too, as do the blades.

The oil seems to be simply burning up. I tried running the mower twice with the blade engaged for a few minutes and each time I had to add a significant amount of oil. It was not leaking...just getting consumed. Needless to say I won't be testing it like that again until I fix this!

Thanks to everyone for your input. Weather permitting tomorrow morning, I'll check that the belt is run on the pulleys properly. I do have the manual, but it was a little difficult for me to follow. It seems that the likely culprit could be the belt running over a guide.

I'll let you know what I find out...

My 89 model has the routing of the belts up under neath the foot running boards. maybe your you model is the same? take the deck off and run the mover and see if it get hot and uses up all the oil? if so you might have the cooling fins pluged or worn out engine and not a deck problem.

Update:

Good news...I think! Here's what's happened today: First, I checked the routing of the belt and verified that it was correct. Check. No blue marks on the belt. So I proceeded to take the deck off. Done. Started the mower...no smoking from the engine. Check. I then proceeded to put the deck back on.

During this process it dawned on me that there was one thing that I had unnecessarily removed the first time that wasn't in the same spot as it appeared to be in the manual (the first time I removed the deck I pretty much removed every pin I found). I'm not sure what it is, but it was a rod (bent on each end) that was connected to the deck that seems to move (slide) a couple of parts on top of the deck. All I know is that when I looked at the mower assembly guide in the manual, it should have been connected from the deck to the back of the deck where another rod is also anchored (for the clutch?). Anyway, I put it on and reattached everything else.

So I started the mower...everything ok so far. Let it warm up and bit and started to drive around. Ok. Then I engaged the mower. Seemed ok. So I started mowing the backyard. Other than running out of gas it was fine and I mowed the whole back yard!

Well, I wish I could remember where I had connected that rod (by pin) the the first time so maybe it would make sense to you all what I had done wrong, but the main thing is I think I'm ok - for the moment!

It started raining again so I'll have to finish the yard at another time. Thank you so much to you that offered advice. I was pretty much ready to give up before I posted this, and your input motivated me to keep trying.

Jeremy

Just a guess, but that rod may be attached to a spindle brake. The default position is with the brake on, so if you remove the rod, it wouldn't take off the spindle brake.

I don't know how that would make you burn oil, but it would definitely put a load on the engine. I'd think the belt would snap or slip before anything happened though.