Diagram of how serpentine belt goes. Last belt had one on pkg.

There's a website that has all this information about all this and manuals everything totally free there are many actually but I personally like few . reliable-store
let me know if u need help
thanks

Here's a link to your belt diagram. 1992 Buick LeSabre Serpentine Belt Routing and Timing Belt Diagrams

Re check the belt routing.

Below is the master help link provided to go through belt routing diagram:---Timing belt, drive belt, serpentine belt, accessory belt, fan belt, engine belt routing diagrams for all types of car models?
Click the link below: ----

http://carbeltrouting.blogspot.in/2012/02/timing-beltdrive-beltserpentine.html
----------This will help. Thanks.

Move the Grand Marquis's serpentine belt tensioner off the serpentine belt with the serpentine belt tool. Pull the belt of the remaining pulleys by hand. Take the belt out of the engine well. Wrap the new belt around the bottom portion of the crankshaft pulley. Follow the belt routing diagram to route the belt over each remaining pulley until only the tensioner remains. Move the Grand Marquis's serpentine belt tensioner aside once more and slip the belt onto the tensioner pulley.Hold the belt in place with one hand while you move the tensioner slowly back into position with the other. Here you can fine the quality AC parts http://www.1airconditioning.com/ac_compresor.htm

Rather than by pass the AC pulley You can actually buy a dummy pulley. It has the same position and size as the the AC pulley but has a frame instead of the AC assembly. In this way you can remove the A and keep all belts etc. the same. The following site has a diagrams for the '95 marquis belt route:- http://www.bestvalueautoparts.com/Replacement_Parts/MERCURY/GRAND_MARQUIS/Illust_c_Belt_Routing.html

First, keep a copy of this diagram as you will need it when you go back to putting it on…



Here’s a link to a “how to” video that will walk you through removal and replacement of your serpentine belt.

Posted by Asker under the 1992 Mercury Grand Marquis for a 1989 model.

Sorry for the delayed response....
I am personally going back to answer your unanswered question.
I do not know if you still need the answer, but am answering it in case you do.

I also do not know if you have the 5.0L or 5.8L Engine or what options (AC/No AC, etc.).

Click on the following free, direct Link. It has the Serpentine/Drive Belt Diagrams for the 1989 Mercury Grand Marquis for both the 5.0L and 5.8L Engines and engine options (AC/No AC, etc.).

http://www.2carpros.com/car_repair_information/year/1989/make/mercury/model/grand_marquis/1989_mercury_grand_marquis_drive_belt_routing_diagram.htm

"HOW TO":
Standard Rules to Removal the Serpentine Belt with an Automatic Tensioner:
1. Find the Tensioner.
2. Using a Serpentine Belt Tensioner Tool, Or Wrench OR Ratchet, Rotate/Move the Tensioner USING THE AVAILABLE NUT (on the Pulley or Arm Base) OR the OPENING (3/8ths or 1/2 inch square opening) rotating the Tensioner Pulley/Arm - moving it away from contact with the belt and towards the area where the belt is not in contact with the Tensioner Pulley. The Tensioner is spring loaded, and is hard to rotate/move.
3. Remove the loosened belt off one of the other more easily accessed Pulleys.
4. DO NOT quickly release the Tensioner, but gently allow the Tensioner to rest in its closed position.

Standard Rules for Installing the Serpentine Belt with an Automatic Tensioner:
a. Pick a Pulley that is most easily accessed. This will usually be on top. This will be the last Pulley that the belt will go on.
b. Using the Diagram: Install the new Serpentine Belt on the remainder of the Pulleys....over, under, left right.
c. Using a Serpentine Belt Tensioner Tool or Wrench or Ratchet Tool: Rotate/Move the Tensioner Pulley/Arm "away" from Belt contact area on the Tensioner. This spring is pretty hard and with a new belt, it will be even harder to install. Rotate/Move this to as-close to the maximum allowed inorder to have enough slack in the belt to get it up and over the last pulley.
d. Using your other hand - Pull the Belt up and over the Last remaining Pulley.
e. Before releasing the pressure on the Tensioner, visually inspect the remainder Pulleys and the Belts' Positioning on them.
Let me know if this helped, or if you have additional information questions. Feel Free to contact me at FixYa.com!

From the Dayco web site:

Try this diagram.

here you go