DIY alternator replacement (Deviation from service manual)

[Jeremy M.]

Hi all, been the better part of a year since I had reason to pop onto the forums. This post isn't looking for help, but instead offering some friendly advice on doing this job in a different way than the service manual describes (especially for those with back issues like me, because this way, the alternator comes out the top).

I recently had my alternator drop out on my '98 LS400 (1UZFE VVT motor), and although I have the service manual, I decided to follow a different path with removing my alternator, because the service manual calls for complete removal of the power steering pump, which I found unnecessary. Instead, I followed the following steps (photos to come at a later date to make it easier to follow along)

Tools you'll need- One each 10, 12, and 14mm wrench and socket. (One stubby ratchet or short 12mm wrench will come in handy, but isn't absolutely necessary) also a few extensions.

Optional but recommended- One fan clutch removal tool. I have found that this style works best. https://shop.advanceautoparts.com/p/product/22983568 If you don't use a specialty tool like this, you will need a second 12mm wrench. Also recommended is a flex-head ratchet

1. Disconnect negative cable from battery and set away from the terminal to prevent accidentally shorting your electrical system later.

2. Remove all intake ducting, up to the throttle body. There are several vacuum lines attached, as well as a PCC hose. There are also a few 10mm bolts securing the intake.

3. Remove the cooling fan and fan clutch. There are four 12mm nuts holding the fan clutch on the pulley, and this is where you will use the removal tool (if you have it) to make your life easier. You can get away without a specialty tool with loosening each nut by tightening another, and on the last nut, using the box end of a wrench to gain some leverage on a stud where the nut has already been removed. You can pull the fan clutch out the top without removing anything else, just be careful not to hit into the radiator and damage any fins.

4. Remove the serpentine/drive belt. A 14mm wrench on the tensioner, and to loosen the tensioner, you rotate it in the counterclockwise direction. Slip the belt off the idler pulley, and after releasing the tensioner, you can remove the belt.

5. Loosen your power steering pump and reservoir- three 10mm bolts secure the reservoir, and three 14mm nuts and bolts secure the pump. Two fasteners are hidden on the bottom side of the passenger side cylinder head, right towards the front. A flex head ratchet works wonders here, otherwise you'll need extensions to get them from underneath the vehicle. You'll be able to use a ratchet on all these bolts, but not the 14mm nut securing the pump from the front, because it's blocked by the power steering pulley. You will NOT need to remove any hoses, but you will need to flex the reservoir around a bit to shift the whole assembly forward a few inches.

6. Now that the power steering pump is out of the way (it doesn't need to go far, not even off the stud it's mounted on) this is where you'll break out your stubby ratchet/12mm wrench. It's a bit of a tight squeeze, but you should be able to reach down from the top and pull off the rubber boot covering the alternator lug and loosen the 12mm nut securing the charging cable.

7. Once the charging cable is off, remove the bolt and nut securing the alternator to the block (both are 14mm). Now you can shift the alternator forward and access the wiring plug in the back. It's a standard pinch-and-pull removal, but mine, with 25 years of age and gunk, was stuck on pretty well. The last thing to remove is a wiring loom bracket for the oxygen sensor plug. This can come off with some persuasion, but it's ultimately easier to cut the electrical tape securing the wire to the bracket and removing the bracket once the alternator has been removed.

8. Remove the alternator! With the power steering pump shifted forward, you will be able to pull the alternator forward and off the stud, then straight up and out the top, without spilling a drop of fluids.

Re-installation steps and torque values will be added to this post at the same time photos are.

[Jeremy M.]

Back again with photos. Full disclosure, some pulleys and wiring brackets are removed in the photos, you do not need to remove anything that hasn't been mentioned, they're just taken off to have a better line-of-sight for the camera.

Installation is the reverse of removal, and everything slides together fairly nicely.

1. You'll start by sliding the alternator onto the stud, letting it hang. Don't slide it back until you've plugged in the connector on the back and slid the rubber boot over top. Next, you can shift it back further and get your charging cable attached. There was not torque spec in the manual (that I could find) but good practice is to tighten the nut for the charging cable until you can't move the cable side to side. Slide the boot over top of the charging cable after it has been secured. If you were able to disconnect the wiring bracket on the alternator, reconnect it. If you cut the tape, peel off the old tape and wrap new tape around the mount and harness.

Next, slide in your bottom alternator bolt and hinge your alternator side to side, lightly pushing on the bottom bolt to find the threads. Once you have both the nut and bolt lightly seated, you can torque them both to 29 ft-lbf.

This is what you should look like at this step.

2. Re-install your power steering pump. The pump will slide straight back, if you meet resistance, double check that your reservoir isn't caught on the cooling hoses attached to the coolant reservoir, and turn the body of the pump on the stud to make sure the mount isn't colliding with the cylinder head.

The bolt holes are a bit tricky to find, but for reference, the top hole of the two is directly beneath the widest portion of the valve cover, pictured here:

The lower bolt is tucked a bit further and just slightly towards the rear of the vehicle. Here's a photo of the mounting holes on a spare cylinder head I have on the bench:

Once all three fasteners are lightly seated on the power steering pump, go ahead and tighten them up. The torque spec is 29 ft-lbf for the two bolts, and 32 ft-lbf for the nut on the front.

Go ahead and secure the three bolts holding your pump reservoir in as well. If you're reading this guide ahead of time, the bolt holes are marked with a red "X". Make sure you don't miss the one hiding underneath the coolant feed line.

 

3. Re-install your belt and cooling fan/ fan clutch. Attached is a photo of the belt routing (you should also have the same routing diagram attached to your hood). Torque spec for the fan clutch nuts is 16 ft-lbf.

When you install your belt, make sure it is sitting in the grooves properly by hand. If it is misaligned, it can jump off when you start the engine and damage components.

 

4. Install your air ducting and vacuum/vent hoses, and reconnect your battery cable. You'll need to go through and re-set your clock, radio presets, and memory seats, but other than that, your job is (almost) done!

5. Check your charging system

Your alternator is installed, but verify your system is working before setting off down the road. With the engine running, you should have about 14 DC volts. Double-checking this now is the best way to keep from immediately getting stranded with a dead battery, and while you're checking it, you can listen for any abnormal sounds from your engine.

 

Torque values:

Alternator mounting nut and bolt: 29 ft-lbf

Power steering bolts: 29 ft-lbf

Power steering nut: 32 ft-lbf

Fan clutch nuts: 16 ft-lbf

Edited May 24, 2023 by Jeremy M.
Adding Torque values at end of post for quick reference