I searched the forum but was unable to find a how to. The question, How do I replace the alternator on my 1990 LS400?

Thanks in advance!

 

start by stopping the power steering pump from above leaking onto your alt.

 

http://www.lextreme.com/alternator.html

 

I replaced the alternator on my '91LS400 last June and here are the notes I made to myself:

ALTERNATOR REMOVAL:

1. Remove battery negative terminal & jack up front end.
2. Remove plastic engine undercover
2. Remove battery cover screw and 12 mm nut
3. Remove 10 mm battery cover nut and lift cover out.
4 Remove the air intake duct,
4. Remove coolant jar cap.
5. Drain coolant through radiator drain ****
6. Remove 17mm coolant filler nut above the thermostat housing.
7. Remove upper radiator hose
8. Retighten radiator drain **** after draining.
9. Remove two transmission cooler hoses at radiator.
10. Remove lower radiator hose.
11, Remove hose connecting radiator to coolant jar.
12. Remove two two radiator support and radiator & fan electrical connector, shround strap
11. Remove serpentine drive belt.
12. Loosen 14mm upper alternator mounting nut
and lower 14mm alternator mounting bolt.
13. remove lower alt bolt then top nut
14. disconnect stuff to alternator and pull out alternator

alternator installation:

1. attach stuff to rear of alt from top:
a) put on lead wire then 12mm securing nut
b) snap in elect connector
c) from below tie lower alt bracket out of the way with string
while struggling to get top
alt hole mounted onto threated 14mm stud. Then tighten upper
14mm nut, then tighten lower 14 mm bolt

2. install serpentine drive belt. slip onto ps pulley last while depressing
tensioner counterclockwise
4. install radiator, and attach white fan electrical connector
then attach shroud strap.
5. Install hose connecting radiator with coolant jar & 2 clamps
6. Install lower radiator hose with 2 clamps
7. install two transmission hoses with 4 clamps.
8. Install upper radiator hose with 2 clamps
9. fill coolant through coolant opening & rad cap / patience
10, add 1 cup tranny fluid
11. install pass side radiator support with 12 mm bolt
12. install air duct
13. install batt - cable
14 install driver side batt cover
15. install coolant
16. Check trans fluid level
17. Install engine undercover

 

It is sooo much easier to take it out through the top...but drain rad, remove lower rad hose and remove the fan shroud / battery/ battery tray...easy peezie.

 

No reason to do anything with the radiator, to remove the alternator. Need ramps.