how to replace alternator

Asked by Nov 04, 2013 at 12:55 PM about the 1998 Cadillac DeVille Concours Sedan FWD

Question type: Maintenance & Repair

i need step by step instructions on how to replace the alternator

3 Answers


Go to "" and look it up online under your autos year, make and model. I recommend you disconnect the battery at the positive post first (moving the cable away from the battery post or just cover the cable end with something) so it does not come into contact with the battery post during alternator removal/replacement, and reconnect the battery last after installation.

2 people found this helpful.

MONDAY, FEBRUARY 9, 2015 97 Deville alternator replacement I recently replaced the alternator on my daughter's 97 Sedan Deville. It was a 140 amp without the heated windshield feature. I read several posts on line about the procedure and a video that was first thing on the google search that was not helpful in the least. With that said, I had to read at least three posts to get enough info to decide to attempt the job. Therefore I decided to write a post that completely cover the steps for removal and list the tools for the job. I have a homemade ramp that I use to change the oil in the Caddy and this is what I used to raise the front high enough for me to slide under the front of the car. The ramp is made of 4 pieces of 2x8 pressure treated lumber. the bottom piece is 30" long and each other piece is 2" shorter than the other screwed together in a stair step manor thus creating the ramp to drive the front tires up on. Get the car at least 6" off the ground and be safe, set the parking brake. Get together a straight blade screwdriver, 15mm socket, 10mm socket, 8mm socket; a 15mm, a 10mm, and a 6mm open end wrench and a 1/2 drive breaker bar. There are four 15mm bolts that hold the alternator in place. But first you have to create access to reach the alternator from underneath the vehicle. Crawl under the front of the car and remove the three 10mm bolts from the black plastic access cover that is between the radiator and the cross member, remove the panel. It is approx. 5" wide and 30" long. Remove the four 10mm bolts from the small metal access panel that is directly below the alternator. After you get this panel off remove the 10mm bolt from the metal clamp on the wire loom bolted to the crossmember and tuck the wire out of the way up on the top of the crossmember. Looking up you will be able to see the two 15mm bolts on the engine side of the alternator along with the battery wire connection and the wire plug above it. Also you will see the cooling fan that you will be removing. Get back up to the top side and remove the plastic cover that goes across the top of the radiator. This can be removed by pulling the plastic push plugs out and pulling up on either end firmly to release it. Take the two long mounting screws out of the passenger side cooling fan, unplug the wiring connector, crawl back under and use the screwdriver to pry open the plastic clamp holding the wire loom to the back of the fan. From topside pull radiator hose aside to lift fan up and out. Lay fan down with blade assembly facing up. Next, You Should disconnect the battery cables and maybe cover the terminals so you don't accidently arc the socket wrench on them when removing the two mounting bolts on that side of the alternator. Locate the upper and lower mounting bolts and remove them completely. Take your 1/2" breaker bar and insert it in the square on the belt tensioner. Push the handle toward the front of the car and carefully slide the serpentine belt off of the alternator pulley. Using your right hand, reach down and hold the belt steady near the bottom of the tensioner and take the left hand and deliberately slide the belt toward the firewall side to get it slid back out of the way of the alternator. Careful not to unravel the route of the belt. Crawl back under and remove the battery wire and the wiring plug from the alternator. Use you 15mm open end wrench to remove the two mounting bolts. The lower bolt may not pull all the way out. Hold your hand under the unit for support. Gently pull the alternator down to clear the bracket. Move the alternator slightly toward the middle. Once you have a little room turn the alternator pulley side down and then twist slightly until it slips out between the radiator and the cross member. If you are deliberate, you will remove it without damaging any of the radiator cooling fins. Install new one in reverse. Took me 3 hours with the trip to the parts store included. This job a fairly easy job. A new NAPA alternator was $154.00 I paid a shop to replace one in 2008 and cost 487.00 for the job and they used a Delco Reman. Do not use a ratcheting wrench on the lower mounting bolt on the engine side. there is not enough room for the ratchet to clear the crossover pipe next to it!

24 people found this helpful.

Is '04 the same as '97?

2 people found this helpful.

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