I have a stanley 54zs. Im replacing the engine to hydro belt and not sure the best route to take with out completely dismantling the whole back end. Theres got to be an easier way.

be sure belt is routed the right way
and disengage lever isn't pulled if its a hydro trans
be sure belt is around pulley on engine

Goto:
http://www.swisherinc.com/media/documents/10277_REV_05_109.pdf for the complete manual.

If there is no sticker on fan shroud area with a drawing of belt routing..Look at belt before removal and draw the routing yourself of how it is routed...you will need a long slim 3/8 ratchet or a 1/2 ratchet to fit between front of engine and inner fender..You may have to remove right side tire and inner plastic splash guard to see the lower part of belt ...this will also make it much easier to remove and replace...The tensioner will have a small square at about the center of it where you will insert the square end of ratchet...If you have neither of these.., parts stores sale a long slim tool just for that purpose...Get parts and make sure they are correct...Remove belt..,The tensioner will be bolted to engine..,( Not the PULLEY)..The pulley is connected to tensioner from factory..Put a small amount of blue lok-tight on bolt threads..install tensioner and belt..Crank engine and safety check all.....Re-install all removed in reverse order.....Complete..........Hope this helps.....Brooks

alldata.com
page 1, line 1 (serp)
Tension is maintained using an automatic tensioner pulley assembly. The drive belt is tensioned by adjusting the position of the idler pulley, accomplished by moving the adjuster bolt on the idler mechanism.

here, pasted in whole.

Serpentine Belt Because serpentine belts use a spring loaded tensioner for adjustment, belt replacement tends to be somewhat easier than it used to be on engines where accessories were pivoted and bolted in place for tension adjustment. Basically, all belt replacement involves is to pivot the tensioner to loosen the belt, then slide the belt off of the pulleys. The two most important points are to pay CLOSE attention to the proper belt routing (since serpentine belts tend to be "snaked'' all different ways through the pulleys) and to make sure the V-ribs are properly seated in all the pulleys.
Although belt routing diagrams have been included in this section, the first places you should check for proper belt routing are the labels in your engine compartment. These should include a belt routing diagram which may reflect changes made during a production run.

1. Disconnect the negative battery cable for safety. This will help assure that no one mistakenly cranks the engine over with your hands between the pulleys, and that the cooling fan cannot activate while servicing the belt(s). NOTE Take a good look at the installed belt and make a note of the routing. Before removing the belt, make sure the routing matches that of the belt routing diagram. If for some reason a diagram does not match (you may not have the original engine or it may have been modified), carefully note the changes on a piece of paper.
2. For tensioners equipped with a 1/2 in. (13mm) square hole, insert the drive end of a large breaker bar into the hole. Use the breaker bar to pivot the tensioner away from the drive belt. For tensioners not equipped with this hole, use the proper-sized socket and breaker bar (or a large handled wrench) on the tensioner idler pulley center bolt to pivot the tensioner away from the belt. This will loosen the belt sufficiently that it can be pulled off of one or more of the pulleys. It is usually easiest to carefully pull the belt out from underneath the tensioner pulley itself.
3. Once the belt is off one of the pulleys, gently pivot the tensioner back into position. DO NOT allow the tensioner to snap back, as this could damage the tensioner's internal parts.
4. Now finish removing the belt from the other pulleys and remove it from the engine.

To install:

1. While referring to the proper routing diagram (which you identified earlier), begin to route the belt over the pulleys, leaving whichever pulley you first released it from for last.
2. Once the belt is mostly in place, carefully pivot the tensioner and position the belt over the final pulley. As you begin to allow the tensioner back into contact with the belt, run your hand around the pulleys and make sure the belt is properly seated in the ribs. If not, release the tension and seat the belt.
3. Once the belt is installed, take another look at all the pulleys to double check your installation.
4. Connect the negative battery cable, then start and run the engine to check belt operation.
5. Once the engine has reached normal operating temperature, turn the ignition OFF and check that the belt tensioner arrow is within the proper adjustment range.

Dealer visit

could be engine timing not right

Make sure your timing marks are lined up and start putting your belt on the rear cam first that would be 1,3,5 cam. Then route it under the water pump and up around the front cam 2,4,6 cam being careful the rear cam don't jump off it's mark. Keep tension on the belt while routing it. Continue routing it over the idler pulley keeping tension on it route it down and around the crank sprocket. Now set your tension pulley and replace the tension pin. Once the belt is set hand crank the engine 2 to 3 complete cycles then recheck your marks. This is for a 2.5 engine. Good luck hope this helps.

Make a drawing of the old belt routing. Some models have a decal in the engine compartment showing the correct routing. Verify that the decal routing does indeed match the routing actually on the engine. Routing must be correct or the new belt won't be the correct length or something will end up running backwards. Locate the belt tensioner. Usually a device with a round body which is slightly offset from the attached pulley. The pulley will be smooth with no ribs. My 302 is best accessed from underneath. On the front of the pulley will be a square hole which will accept the square drive of a socket wrench handle with no socket attached. Insert the socket handle into the hole and use the handle to defeat the spring tension by moving it left or right. This removes the tension from the belt and allows you to wiggle the old belt out and the new one in. Be sure to keep the tension off the tensioner while removing and replacing the belt. You do not want it to slip and catch your fingers under the belt and you will need the "slackness" of the belt to give you room to maneuver the belt onto the pulleys. A helper to hold the tension off is very useful. Compare the old belt and the new one for length. They need to be very close. Now is a good time to inspect the tensioner for sloppy pulley bearings or looseness in the hinge joint between the offset base and the pulley. They commonly fail and are available at any auto parts store. Position the new belt with the correct routing onto the pulleys. I use duct tape or zip ties to temporarily hold the belt in place on the pulley ribs. Once the belt is in position on all the pulleys, slowly release the tension on the tensioner and allow the belt to tighten up and seat itself in the ribs. Be certain that the belt is seated correctly in all the ribs and not on top or off to the side. Verify correct routing. Remove duct tape and ties and start engine. I will start the engine for a minute or so while listening for unusual noise. I will then shut the engine off and visually inspect the belt again to make sure it is properly and completely seated in the ribs. Note that some models do not use the square hole on the front of the tensioner, but rather use a hex headed bolt. In that case use a wrench instead of the socket handle.

REMOVAL & INSTALLATION Because serpentine belts use a spring loaded tensioner for adjustment, belt replacement tends to be somewhat easier than it used to be on engines where accessories were pivoted and bolted in place for tension adjustment. Basically, all belt replacement involves is to pivot the tensioner to loosen the belt, then slide the belt off of the pulleys. The two most important points are to pay CLOSE attention to the proper belt routing (since serpentine belts tend to be "snaked'' all different ways through the pulleys) and to make sure the V-ribs are properly seated in all the pulleys. Although belt routing diagrams have been included in this section, the first places you should check for proper belt routing are the labels in your engine compartment. These should include a belt routing diagram which may reflect changes made during a production run.

1. Disconnect the negative battery cable for safety. This will help assure that no one mistakenly cranks the engine over with your hands between the pulleys, and that the cooling fan cannot activate while servicing the belt(s). NOTE: Take a good look at the installed belt and make a note of the routing. Before removing the belt, make sure the routing matches that of the belt routing label or one of the diagrams in this book. If for some reason a diagram does not match (you may not have the original engine or it may have been modified), carefully note the changes on a piece of paper.
   
2. For tensioners equipped with a 1⁄2 in. (13mm) square hole, insert the drive end of a large breaker bar into the hole. Use the breaker bar to pivot the tensioner away from the drive belt. For tensioners not equipped with this hole, use the proper-sized socket and breaker bar (or a large handled wrench) on the tensioner idler pulley center bolt to pivot the tensioner away from the belt. This will loosen the belt sufficiently that it can be pulled off of one or more of the pulleys. It is usually easiest to carefully pull the belt out from underneath the tensioner pulley itself.
3. Once the belt is off one of the pulleys, gently pivot the tensioner back into position. DO NOT allow the tensioner to snap back, as this could damage the tensioner's internal parts.
4. Now finish removing the belt from the other pulleys and remove it from the engine. To install:
   
5. While referring to the proper routing diagram (which you identified earlier), begin to route the belt over the pulleys, leaving whichever pulley you first released it from for last.
6. Once the belt is mostly in place, carefully pivot the tensioner and position the belt over the final pulley. As you begin to allow the tensioner back into contact with the belt, run your hand around the pulleys and make sure the belt is properly seated in the ribs. If not, release the tension and seat the belt.
7. Once the belt is installed, take another look at all the pulleys to double check your installation.
8. Connect the negative battery cable, then start and run the engine to check belt operation.
9. Once the engine has reached normal operating temperature, turn the ignition OFF and check that the belt tensioner arrow is within the proper adjustment range. Fig. 1: Often the underhood label will display the serpentine drive belt routing
   Fig. 2: Relieve the belt tension by pivoting the automatic tensioner away from the belt, then remove the belt
   Fig. 3: Verifying serpentine belt alignment in the pulley
   Fig. 4: Fig. 1 Accessory V-belt routing (alternator) — Mazda MPV 3.0L engine
   Fig. 5: Fig. 2 Accessory V-belt routing (power steering) — Mazda MPV 3.0L engine
   Fig. 6: Fig. 3 Accessory V-belt routing (A/C compressor) — Mazda MPV 3.0L engine