I have a Poulan (Weedeater) 38" mower deck that is always engaged. The new belt is loose enough to pull off the engine pulley, but when I start the engine, the blades start turning. I have pulled the deck out at least 20 times, adjusted the manual engage/disengage bolt from one end to another (about 2" span), added a spring to pull the idler pulley so the belt loosens, and other adjustments. This one makes no sense. I have the belt routed as the manual shows but I cannot get it to disengage. Sometimes it will drop off the engine pulley by itself. Very odd. Anyone seen something like this?

I am wondering if you have the right belt for that machine. or possible its not installed properly.The belt should be tight when engaged. The tightener may not be working as well. These are things to check. Does the belt try to tighten up when you engage it?
I am wondering if the wrong belt was the reason why some one lowered the deck too low.

You either have a bad bearing on one of the pulleys or one is loose and moving up and down drawing the belt when it is engaged. I would pull the mower deck off and go through it .

Your mower uses the #144200 belt by A.Y.P. This belt is 1/2" by 88.3" You must use a wrapped belt for this application. The #144200 is available through www.searspartsdirect.com and will also be readily available at your local repair shop.
Good luck!

No it should not be against the gear shifter look over and try to rearrange.You may have to turn a bolt or two.Thanks for asking and I hope this helps out.Please leave me 4 thumbs up.

The squeal is most likely the drive belt moving against a pulley or tensioner which is frozen due to a bad bearing. This can start a fire at worst and burn through the belt at the least. You need to have someone take a look at your belts.

Sounds like the mower belt may not be routed correctly around the pulleys or may be running on the wrong side of a belt guard. Also check under the deck to make sure there are no obstructions to the turning of the blade or bent blades....you did not state where the hammering was coming from ( engine or deck ) I can only assume that it is on the deck....so these are the things I would check. Also check the tightness of the bolt on the main pulley sheave (the pulley on the bottom of the engine that drives the belt. the bolt is in the center hole of the pulley) if it is loose it can cause misalignment of the belt and juddering of the deck. If the bolt is tight, remove the belt from the engine pulley sheave and start the engine and look to see that the crankshaft is not bent causing the pulley to wobble....worst case scenario....will require new engine...hope this helps... ;-D

NO IF YOU HAVE THE RIGHT BELT IT SHOULD GO ON

need a diagram of how to put a deck belt on a 15.5 hp/38" cut 5 speed poulan lawn mower model number 9601200-3801

42 inch poulan belt broke on mower deck diagram to replace new belt

make sure the pulleys are aligned and then check for burrs or sharp steel cuts on the pulleys as for the battery check for a short or bare wire.