deekim

iTrader: (-1)

does anyone have a detailed explanation possibly with pictures on how to replace an alternator on a 91 ls400? is this an easy project for someone who has never worked on a car mechanicly?

Kansas

Replacing an alternator on a gen 1 LS is probably not much different than what's described in this recent thread for a 2000 LS400: https://www.clublexus.com/forums/ls4...placement.html

Note that Garage7RP said he replaced the alternator on his gen 1 LS without having remove the the PS pump pulley like some apparently have had to do on the later LS400s.

I've never replaced the alternator on either my 90 LS or current 00 LS but I have on other cars -- usually pretty simple ... unplug, unbolt, etc.

As far as it being an easy job "for someone who has never worked on a car mechanicly", it's certainly a far easier job than many.

You'll need a decent set of metric tools (probably a socket set and maybe some wrenches) and a good set of jack stands or ramps to elevate the car safely.

If your alternator has failed due to leakage from the PS pump, consider making a protective guard for your new alternator from a plastic bottle -- some cut up a bleach bottle like in the attached photo.

deekim

iTrader: (-1)

how would i know if its due to a leakage from my ps? i would know until i took it off? I took my car into kragen to get a check on my alternator, they said its a diode problem. what is a 'diode'?

LiCelsior

iTrader: (32)

LOL Kansas!!!! i love that hahahha.

Garage7RP

iTrader: (1)

Kansas, that is a sweet "protection"!

"If you use it, cover it!" LoL

A Diode is an electric component of the alternator. I don't think you could just replace the diode unless you go to a alternator remanufacture place.

I would just replace the alternator. Kragen offers lifetime warranty on alternators.

trukn1

Deekim,, the alternator replacement is not a hard one to accomplish, but it may be a lil frustrating if you have never worked on a car before.

1. Elevate car safely (ramps, jackstands) b/c the alternator WILL have to be removed from the bottom of the car. Remember to disconnect the battery after car has been lifted.

2.Loosen the belt off of the drive pulleys by way of the drive belt tensioner (IIRC a 12 MM socket with an extension will do the trick).

3. Directly under the belt tensioner you can actually loosen the top bolt for the alternator.

4. Now this is where you start to learn all new swear words,, you will have to go under the car and manuever you hands up to the bottom off the alternator to loosen the bottom bolt. Once loosened, slide the entire thing forward and off of it's mounting bolts. Now the trick comes into play b/c you WILL look at how big the alternator is and how big the opening is at the bottom to pull it out and think to yourself NO WAY!!! It will come out of there; may have to manuever it a little or even loosen a few of the other smaller lines under the car up to do so.

5. Once you manage to get the alternator out of the opening and alot closer to the ground, go ahead and loosen up the connections on the alternator itself, and unplug the main plug. Remember to transfer the shield from the old one to the new one (protects the bottom from debris kicking up from the road).

6. Install is reverse of removal. In putting the new alternator thru the opening to get it back in place, if you are by yourself, that alternator WILL get very heavy REALLY quick, even though it doesn't weigh that much. YOU WILL have to twist and turn it several different ways to get the new one in, as you did the old one out. If you have a friend with you, it would help you on the ground, to have the try to grab it from the top(offers a little support for you) while you try to maneuver it thru the small opening. YOU WILL CURSE THIS CAR AS WELL AS THE DESIGN THE VERY FIRST TIME YOU HAVE TO CHANGE THIS ALTERNATOR. WHAT MAKES IT SO HARD IS THAT THE FRONT SWAY BAR IS IN THE WAY. NOT ENOUGH TO PREVENT IT FROM COMING OUT, BUT JUST ENOUGH TO BE A NEUSIANCE TO YOU WHILE TRYING TO WORK THIS.

7. Re-snake the serpentine belt around all of it's respective pulleys, using the diagram on your hood as a guide and then use the tensioner pulley (same as when you loosened) to take pressure off the system so you can slip the belt back over it. A friend here to route the belt while you hold pressure off the tensioner will really help you. It can be done by yourself, however in this phase 2 people are better than one.

8. Re-connect battery

9. Lower car.

It sounds a little terrifying, but it really is not that bad. Expect to spend about 2 hours changing if you are a true novice. Sad to say, but I have done this so many times due to leaky PS (B4 it was fixed), as well as just defective re-man'ed alternators that I can do this whole process in close to 45 minutes now.

deanshark

The way trukn1 said sounds good. It's not that bad as long as you can twist a wrench. Ya gotta learn sometime, it just takes longer. I had mine out when I did my T-belt. I should have put a new one in then b/c it was COVERED with PS fluid. But that's my own stupidity. It can't be worse then on my 91 Grand Prix 3.4 where ya gotta drop the sub-frame and pull the axle out. (Did that twice) Just don't force anything where it wont go, be careful unhooking the wires, take your time and you'll be all set. That protection that Kansas has shown looks pretty good but I think sheetmetal would be better. It's always way cheaper to DIY then bring it to a shop. Good luck

mr.ajandkj

I like the cover idea, but only concern would be proper cooling of the alternator...there's a reason those fins are molded in to the case design...and in the pic it looks like the bleach bottle was left closed on the back-end, meaning no airflow through the alternator. This is a sure method to kill it quickly from heat. It would likely be sufficient to only cover the top-side of the alternator directly under the PS, leaving the bottom half and back open for cooling airflow.

deanshark

Now that I look at the pic better I can see what your saying, that back does need to be open. I didn't realize the whole thing was rapped. It should be just covering the top, enough to divert the PS fluid when it leaks.

Kansas

People have been using similar bleach bottle "alternator condoms" on 90-94 LS400s for nearly 20 years without "killing alternators from heat".

j stuff

iTrader: (5)

i have created my cover and will install the alternator tomorrow. I have opened the back for the airflow and the plug thats back there

dc893

Anybody ever done this with a cover. My alternator is heading south but I have a Denso Reman on the way and will put it in on Saturday. I'm sure we all know the reason is the stupid PS pump. Wouldn't a cover like this cause some heat issues or possibly melt? I will get the pump replaced later on next month also. I was just wondering in the meantime if this is safe or even some good insurance in case the new pump leaks. I'm probably gonna do this but I am curious if anybody here has done this.

PureDrifter

iTrader: (10)

just hold off and do it all together...

Yamae

I inserted a thin aluminum plate in between the PS pump and the alternator expecting no more alternator failure. I once had a leaking problem and both the PS pump and the alternator were replaced.

In case of a 98 JDM, the space between those two is narrow enough to hold it tight. Edges of the plate were bent automatically when the PS pump was installed because the space was quite limited. I also bent some more aiming the leaking oil to drop not to the slip ring area where the leaking oil causes a problem.

I also added an insulator above the terminal B cutting an old CD to avoid the short circuit problem. CDs are made of polycarbonate which withstands up to 180 degrees C and you almost don't need to worry about the temperature problem. It has been almost 2 years since the job was done. Recently I notice minor PS pump oil leak from the hose but the aluminum plate is protecting the alternator nicely. The leakage is very small and the reservoir level is not changing by my eyes but my next project will be to replace the 16 years old hose.

dc893

Not sure how much longer its going to last, but that is what I want to do. I also wanted to prevent the same thing from happening again in the future.

arigato gozaimasu Yamae. I might go ahead and do what you did. Seems simple enough to put something like that together.