Automobile Repair/99 mercury cougar alternator replacement

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Alternator replacement: The placement of the alternator in the 1999 Mercury Cougar can really take the fun out of performing your own automotive repair, but hopefully with these tips you can avoid the 6-hour job taking days instead.

1. Disconnect the negative battery cable.

2. Using a 3/8" drive, release tension on the tensioner and slip the belt off of an accessory.

3. Loosen the passenger side front wheel lug nuts, then raise front of vehicle and remove wheel.

4. Reinstall two adjacent lug nuts onto the brake rotor and using a prybar on the lugnuts and a socket with a breaker bar, loosen and remove the nut from the splined half shaft(this nut supposedly looses its torque ability and needs to be replaced after being loosened).

5. Remove the Stabilizer bar link. This will require two wrenches, one placed near the rubber seal area. (This step caused me a 3-day delay as I had to order a new one when the nut broke off with the bolt intake)

6. Remove the steering knuckle pinch bolt and separate the ball joint from the "A"-shaped suspension component with the appropriate tool or prybar.

7. Remove the "Y"-shaped exhaust pipe from underneath the vehicle. Spraying a lubricant on the 6 studs and nuts will aid the removal of these nuts. (Stripping of these threads is easily done with the galling that can happen from the hot conditions it has undergone. This accounts to adding another 3 days to my repair.If possible tighten the nut 1/8 of a turn before removing to keep from pulling rust into threads)

8. Remove the half shaft after extracting it from the steering nuckle. (It may be just as easy to remove the nuckle prior to removal of the half shaft, even though this requires removing the ABS sensor, brake caliper, and rotor.) A slide hammer can assist on freeing the half shaft from the other half shaft.

9. Loosen the 5 nuts needed to remove the half shaft that goes into the transmission. Apparently this half shaft is balanced from the factory and should be reinstalled in the same alignment, so mark the transaxle and the half shaft to make this possible. Remove the half shaft.

10. There are 3 electrical connections to the alternator: a 3-pin connector that can be removed by slipping off the clip, a 1-pin connector that is removed by gently prying the plastic clip portion up, and a battery cable sized cable that attaches with a nut that can be removed with a 3/16" socket.

11. There are now 4 bolts that need to be loosened before the alternator can be removed. Three of the bolts are easily reached, while the 4th is not visible and will have to be felt for. A 13mm socket will be needed to remove these bolts. The exhaust manifold and the attached O2 sensor blocks access to the hidden bolt, and removal of the manifold has its own set of hidden bolts which makes removal of the manifold to access the alternator bolt unfeasible.

12. Installation is the reverse of the above, but it is highly recommended that you replace the O2 sensor that is now exposed. It uses a square connector, not a round one like the more accessible "catalyst monitor" sensors. This vehicle has a whopping 4 sensors distributed over 2 banks. If you choose to replace this sensor, a tip on removing the electrical connector: find a 3-inch or so 3/16" diameter or less piece of metal(I used a tap) and using one hand to feel for the access hole which will point to the rear of the vehicle, use the other hand with the metal piece to insert into the hole and releasing the clip, pull on the connector to disconnect the heated oxygen sensor.

Alternative method[edit | edit source]

This task can also be accomplished WITHOUT removing the drive shafts.

Jack the car up as high as possible and support with jack stands.

1. Disconnect the battery.

2. Remove the passenger side wheel & inner fender well covers


4. Remove the serpentine belt from the alternator.

6. Unbolt the steering joint & press out of the steering arm.

At this point you should be able to see the bottom portion of the alternator

9. Use a 13mm socket with a universal joint on the end of a long extension to get to the upper alternator bolt. I was able to reach around into the wheel well with my right hand up to the top of the alternator bolt to help guide the socket onto the bolt.

11. The rear alternator bracket is removed with a 10mm socket.

12. Once the bolts are out you make need to pry the alternator out of the bottom of its mount.

13. Once loose, pivot the alternator on its pulley down towards the control arm. If you are having problems bringing the alterantor down past the rubber boot, just rotate the brake disk and it will walk the alternator out. You will have easy access to the electrical connections.

Replace with new alternator and reverse the process.

While you are down there you can splice a jumper wire from the Red wire in the three wire plug over to the "Output" terminal of the alternator.

Question: Why?

Answer: It gives the voltage regulator a better reading than the factory wire that runs all over the engine compartment. The factory did the same thing in the later model cars. I think there was even a recall for this. If your battery light flickers when the engine is rev'd up than this is an inexpensive mod that may fix your problems.


I've done this job and it is a BEAR!!! I recommend that one has access to a lift as life will be a lot easier. Also power air tools with a flex shaft extension* for sockets. This will alleviate some disconneting of components for access purposes.

This is a job one will not want to repeat so I recommend that you spend the money and buy a good replacement alternator-I got a rebuilt one with a 3 yr. warranty. ($170).

Reassembly can be difficult too. I have long arms so I could reach through from the middle of the car as there is a small passage way. I found the reconnecting of wires to be VERY difficult-took several attempts to align things and tighten.

Absolutely make sure to properly put on the serpentine belt-align it and release the tensioner-making sure it is in the proper grooves-no overlap of pulleys as this stress on start up may in my opinion crack one's alternator case.