Replacing Alternator


Asked by Nov 17, 2015 at 08:46 PM about the 1996 Subaru Impreza 2 Dr LX AWD Coupe

Question type: Maintenance & Repair

Can any one comment on replacing the alternator by oneself? Any one with
the experience of having done this? I have a 1996 Subaru Impreza and the
alternator is definitely going. All the warning signs, - flickering dash lights
and headlights. I am mechanically handy and have done other things myself.
Have new battery and new starter, just hard right now to squeeze out the $$
for another major repair cost.

8 Answers


It is really not all that hard if you have some basic tools and some mechanical experience. Be sure and disconnect the battery first. Check your belts while you are at it as this is the time to replace them.

3 out of 3 people think this is helpful.

Like he said, not the most difficult job- but on a modern car, more difficult than an old car- the belts will be the hard part- and the diagnosis- before you jump in, make sure your alternator really IS blown- so many questions here on this site demonstrate that people just guess, change out part after part, and still have whatever problem they started with- don't let THIS happen to you-

3 out of 3 people think this is helpful.

I agree with them use a voltage meter on the battery with the car idling put the voltage meter on the battery pos to pos neg to neg and test the voltage if the alt is working properly is should show a reading of 13.4-13.5 volts any less and I would start with the belt unless the voltage continuously drops with the car at idle

3 out of 3 people think this is helpful.

#1 and most important is make a diagram of the serpentine belt. On some engines the belt routing is very simple, but on others it is very complicated. There may be a diagram for the belt on a sticker under the hood. #2 DISCONNECT the BATTERY #3 remove the wiring from the alternator #4 remove the alternator then reassemble in reverse order.

3 out of 3 people think this is helpful.

Easier than it appears. TOOLS 10 and 12mm sockets, 3/8" drive, one or two short extensions. PROCEDURE Remove 10mm bolts from finger guards; flip driver side one out of the way to expose alt's main 12mm forward facing bolt if necessary. Loosen this 12mm main bolt a few turns so that passenger side finger guard can be lifted and pried off. Then loosen a couple turns the now-visible FRONT-facing short 12mm lock-bolt just under the top run of the alt belt Now loosen the TOP-mounted long alt adjustment 12mm bolt either 28 or 32 full turns to allow alt to swivel down far enough to remove old belt. Now remove both that short lock bolt and the main alt bolts fully. (Try not to lose either the lock-bolt's anchor nut nor the goofy- looking tabbed main bolt nut rearward of the mount. You'll now be able to rotate the alt UP and down repeatedly as you pry it off its mount. Use a big screwdriver or crowbar GENTLY if it seems tight. Reverse all steps to replace. If the new alt is very tight on its bracket use a RUBBER hammer to nudge in until you can slide the main bolt through its two holes. THEN attach rear tabbed nut and tighten a few turns before proceeding. You'll then want to swing the alt up soomewhat to be in the range of the adjuster slide in order to mount the lock bolt and its adjuster-nut. Do NOT over tighten belt. If it chirps or squeals on cold starts at end limits just loosen lock-bolt and tighten top adjuster bolt 2 full turns. Note that a NEW alt belt will stretch initially, requiring tightening after a few hours use. TOTAL TIME First time, 30-45 min. Routinely, 15-20 min. I taught my daughter to do this over the phone from Chicago. Believe me, if she can do it you can!

2 out of 2 people think this is helpful.

Thank you all for the posts! I have watched a few video's and have tested using the volt meter. With the car running and a load on, it fluctuates between 12.6 and 13.26. The engine fluctuates also. When I shut lights, etc. off, engine still running, meter reading drops to 14.00 - 13.99. With engine off and after sitting for a few minutes, meter reads 12.55. I also went to AutoZone, where they tested for free, first test came up battery no good. It is a month old. Tested again, battery showed good, then showed alternator bad, regulator bad. I didn't get a print out.

1 out of 1 people think this is helpful.

Time for an alt. I would also advise u that while u have the alt off now would prob be a good time to change the belt as well depending on when the last time the belt was changed

1 out of 1 people think this is helpful.

Subie alts use an internal voltage regulator that becomes intermittent when hot. Serious problem in the 90s but faded from prevalence as the noughts progressed, The actual alt bearings are good for a million miles. Hence most are rebuilt with new internal regulators.

1 out of 1 people think this is helpful.

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