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There are a number of write-ups out there, but none are exactly applicable to the 1997 model year; they suggest steps that lead to unnecessary work such as removing the PS pump, PS pump pulley, shrouds, hoses, or other stuff. The 1997 FSM procedure is correct; I'll simply be adding some additional hints and photos. My steps shamelessly borrow from the procedure posted for the 1998 LS400 by listensr10 on another forum; however much is modified. Reader's Digest version of this post: On the 1997 LS400, the alternator comes out the bottom; there is room!
1. Raise front of car; ramps or jack stands. Though some bolts can be reached from above, it's easier to do all work from below with one exception: removing the accessory belt.
3. Remove the under-engine plastic cover. This is secured with 10 mm bolts. (you will now be able to see the underside of the alternator).
4. Lift to un-clip the plastic cover that is forward of the battery. Remove the single 10 mm bolt that secures the plastic cover / air intake assembly over the radiator, and remove the cover.
5. Check to see you have the sticker showing the fan belt routing under your hood (if not, make notes), the remove the fan belt. This is simple using a 14 mm socket with a 4” extension on the belt tensioner, rotate counter-clockwise to relieve tension and just slip off the belt. Note: The tensioner pulley is a smooth (non-ribbed) pulley located just to the right of the power steering pulley. It has a protruding 14 mm bolt head.
6. Working from below, loosen the 14 mm nut from the upper alternator mounting stud, and leave it loosely in place for now. Remove the the 14mm alternator lower mounting bolt. Note: The bolt has a shallow head. Cheap sockets often have excessive chamfer at the end; those may slip, partially rounding off the bolt head. That can lead to a world of hurt! As of this writing, a good choice is the Harbor Freight deep well impact socket (they are flat black). Yes, arguable quality tools, but the point is this particular socket has little chamfer, is six point, and grabs the alternator bolt very well. Other high quality sockets will certainly work well too.
Alternator mounting stud and mounting bolt locations; alternator obviously has been removed in this photo.
7. The cables are restrained by cable clips and a small bracket attached to the alternator. Use an 1/4" drive 8 mm socket to reach the nut behind the bracket and remove it. The bracket blocks the sight line to the nut, so you must do this by feel. You may be tempted to try to undo the plastic cable clip from the bracket instead; possible, but it can easily lead to a broken clip; they are old and a bit brittle. I prefer to remove the bracket.
8. Remove the two 10 mm screws from the cushion mount that holds the power steering oil line to two tabs that stick out from the oil pan. Move the line to the side a bit to give you room for the alternator to come out.
9. You will have two wire sets to remove from the alternator working from below. The first is the “terminal B” heavier wire. Remove the rubber boot to access the 12 mm nut. A 1/4" drive socket works well. Note: If the alternator has been changed out before, it may have a 13 mm nut. I kept the original 12 mm nut to reuse.
10. To more easily remove the next wire set, you can now remove the upper mounting nut and slide the alternator off the mounting post. Then rotate the alternator so you can access the wire connector. Remove the rubber boot. On one side (the long outside edge) there is a tab you can push in; then you can (with difficulty in my case) wiggle the connector off. Note: That little tab tends to stick in, and it can take some force plus wiggling to release it. Try not to break it.
Alternator connector. The release tab is on the top and hidden when the alternator is in place.
11. With alternator fully disconnected, wiggle it out through the bottom. Use the space that is aft of the two tabs that stick out from the oil pan. Trust me, there is enough space. If you go forward of the tabs, it's not going to work. Hint: It comes out with the pulley facing up.
This shows the space where the alternator can come out. Wish I had aimed the camera more to the left, but you get the idea. Stay aft of the tabs sticking out from the oil pan!
12. Prepare the new alternator by removing the 8mm nut in the position where the cable bracket will attach. Remove the B stud nut and washer.
13. Assembly is the reverse. Wiggle the alternator in, pulley up, through the open space aft of the oil pan tabs. Then, hang it from the upper stud, and loosely install the nut. With the lower bolt still out, you can pivot the alternator to make installing the wires easier. Make sure the tab on the push-on connector engages; on mine I had to push hard on the connector before it would seat.
14. Torque the mounting bolt and nut to 29 ft-lb.
15. It's prudent to ensure the battery is charged before the first start with the new alternator. Follow the instructions that came with the replacement alternator for the check out procedure. But basically, you will start the car, turn the headlights on, wait for the idle to stabilize, and then check the voltage at the battery. You should see somewhere in the range of 13.2-14.5 VDC depending on outside temperature. Make sure there is no squealing or smoke coming from the alternator.
Footnote: Because mine failed 100 miles from home on a Saturday, I had to buy what was in stock locally. The first one I installed, a Carquest rebuild from Advance Auto, lasted about 5 minutes before the voltage dropped to battery voltage, and the alternator started smoking. AA cheerfully accepted the return. The second one, from O'Reilly's, is working fine (knock on wood). Both were rebuilt in Mexico.
10. To more easily remove the next wire set, you can now remove the upper mounting nut and slide the alternator off the mounting post. Then rotate the alternator so you can access the wire connector. Remove the rubber boot. On one side (the long outside edge) there is a tab you can push in; then you can (with difficulty in my case) wiggle the connector off. Note: That little tab tends to stick in, and it can take some force plus wiggling to release it. Try not to break it.
Quite often 98% of your time is spent on this step
06-17-18, 10:26 AM
Procedure to Replace Alternator on a 1997 LS400
