Alternator Questions

by **AmnJoker333** » Wed Feb 15, 2012 10:43 pm

I've got a 1995 Subaru WRX STI as my daily driver while I am here in Japan. The alternator belt broke on it last night, and it looks like the serpentine belt isn't gonna be much further behind it (kind of frayed around the edges). Leading up to this, my voltage meter next to my boost gauge would give me erratic readings and the headlights and dash lights would dim and brighten occasionally. Would the impending belt failure be a cause of these readings, or should I also replace the alternator while I am under the hood this weekend?

In return for the advice, some pictures.

by **warlock4u** » Wed Feb 15, 2012 10:51 pm

You may as well replace the alternator, its not going to hurt anything. It could possibly be the reason the belt broke. Btw, I am guessing the car is used, do you have a service history? If so, when was the time the timing belt was changed?

Enjoy the car, we never got anything that cool stateside

by **bonanacrom** » Wed Feb 15, 2012 10:53 pm

The alternator is what charges the battery. The battery starts the car then the alternator takes over supplying power to the lights and dash ( and so forth ) and keeps the battery at full power. If there is no alternator belt then your running everything off the battery and it will not last. Basic maintenance of good belts and keeping the fluids topped off will keep a vehicle in good shape. No need to replace the alternator.

by **majorhavoc** » Wed Feb 15, 2012 11:09 pm

What a coincidence! I broke the alternator belt on my Mazda Protege last weekend. I didn't realize I broke it at first, or maybe it didn't go all at once. My first clue something was wrong was my windshield wipers seemed a little ..... tired. I couldn't really say they seemed slow, just not quite as snappy as usual. Then I noticed the heat wasn't working. I shut off every electrical accessory and managed to limp home.

In short, a bad alternator belt will wreck havoc with your car's electrical system and certainly cause the symptoms you're experiencing. To replace it you're going to have to loosen the bolts on your alternator anyway (and for your serpentine belt, your A/C compressor and/or your water pump as well). The hardest part of the job is just figuring out where and what to loosen. Unless you strongly suspect your alternator is on it's last legs, my advice is to just replace the two belts and see if that doesn't clear up everything. I suspect it will. If it doesn't, you'll find your second time under the hood will go a lot faster since you'll know your way around. You can then replace the alternator at that point.

by **yossarian** » Wed Feb 15, 2012 11:19 pm

I don't know about over there but in the States just about any parts store will test your alternator for free. This isn't always a reliable test but it can point you in the right direction.

by **Dawgboy** » Thu Feb 16, 2012 1:55 am

If you are replacing the serpentine belt, you might also want to check the tensioner as they are prone to fail. It's not too difficult to replace on most cars once you have the belts off. A neighbor just paid 200 to have it done on a Dodge Dakota.

by **M14fan** » Thu Feb 16, 2012 6:00 am

It costs nothing to have Auto Zone test your alternator. Subaru alternators on the other hand are VERY expensive.

by **EmbraceTheHate** » Thu Feb 16, 2012 6:09 am

Make sure all pulleys spin freely, there is a reason your belt broke.

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by **jamoni** » Thu Feb 16, 2012 9:35 am

Just test all the pulleys to make sure they turn freely and well. Check to make sure there are no sharp edges on them or on anything that might touch the belts.
Replace the belts. Drive for a while. If you are still having electrical issues (99% sure you won't) then go from there.
In other words, fix the known problem first, to see if that's the only problem.

by **RESCUE-K9** » Thu Feb 16, 2012 5:06 pm

jamoni wrote:Just test all the pulleys to make sure they turn freely and well. Check to make sure there are no sharp edges on them or on anything that might touch the belts.
Replace the belts. Drive for a while. If you are still having electrical issues (99% sure you won't) then go from there.
In other words, fix the known problem first, to see if that's the only problem.

I would bet it was starting to lock up and that what broke the belt

by **MaconCJ7** » Thu Feb 16, 2012 5:19 pm

RESCUE-K9 wrote:I would bet it was starting to lock up and that what broke the belt

I'm good with the guess that it was a 1995 car and the folks that owned it didn't do much more than change the oil and tires. Especially if it was a hand-me-down that's found on every foreign base. I've also known people to do zero preventative maintenance, including oil changes. One of those cars burnt to the ground on the side of the freeway. Never underestimate the lack of vehicular maintenance that people perform.

by **GentryMillMan** » Thu Feb 16, 2012 5:42 pm

The belt is the weak link not the alternator.
If you don't know when it was last changed or what it looked like last week then it is probably just a neglected belt that finally gave up.

Check the pulleys to make sure they spin and put a new belts (serpentine too) on it and see what it does.
Chances are that you will be just fine. If it acts up go to autozone and have them check the alternator and battery.

by **AmnJoker333** » Thu Feb 16, 2012 8:55 pm

Thanks for the advice guys. I checked the pulleys and everything seems to be turning okay. Got the alternator belt installed, and went ahead and swapped out of the AC belt as well (it was looking pretty chewed up). The remains of the alternator belt were just a few strings in my engine compartment. Seems to be doing better, but I busted a piece of the tensioner pulley in the process :oops:

(the part the screw that moves it up and down threads into). About 80 bucks later, I got that on order and it should come in tomorrow.

by **colinz** » Thu Feb 23, 2012 8:35 am

The alternator belt could have chewed out the AC belt when it was fraying and deciding to come apart.

by **NC5thcav** » Thu Feb 23, 2012 4:01 pm

majorhavoc wrote:In short, a bad alternator belt will wreck havoc with your car's electrical system and certainly cause the symptoms you're experiencing. To replace it you're going to have to loosen the bolts on your alternator anyway (and for your serpentine belt, your A/C compressor and/or your water pump as well). The hardest part of the job is just figuring out where and what to loosen.

You don't have to loosen any bolts on a serpentine belt system to replace the belt. The belt tensioner moves. You but a wrench or ratchet on the tensioner and move it to loosen and remove the belt . The tensioner is spring loaded, so you have to hold it in place while taking the belt off.

by **yossarian** » Thu Feb 23, 2012 6:36 pm

NC5thcav wrote:
You don't have to loosen any bolts on a serpentine belt system to replace the belt. The belt tensioner moves. You but a wrench or ratchet on the tensioner and move it to loosen and remove the belt . The tensioner is spring loaded, so you have to hold it in place while taking the belt off.

While that's often true it isn't always the case. Some do require the loosening of bolts.

by **albersondh** » Fri Feb 24, 2012 8:43 pm

Im no JDM Subie expert, but, I would bet the serpininte belt you are refering to is your timing belt. It should be a horizontaly opposed (boxer) engine and it is either SOHC or DOHC, proly SOHC because of the year, USDM it would be a EJ20 or EJ255-EJ257 (USDM STI). Regardless, if the belt your refering to as your serpintine belt is your timing belt, change it, or have it changed ASAP. To my knowledge all EJ motors (USDM anyways) are interfearance motors. If that belt breaks, and you are SOHC or DOHC, your valves are going straight into you pistons and your buying a new motor. Changing a boxer timing belt can be intimidating the first time especialy if its a DOHC (4 cams) motor. Just get a manual and follow the steps by the numbers and you cant go wrong. Replace all the pulleys and the tensioner while your there. Plan on about $200-$300 in parts.

by **crypto** » Fri Feb 24, 2012 8:50 pm

albersondh wrote:Im no JDM Subie expert, but, I would bet the serpininte belt you are refering to is your timing belt.

Are you high?

I'm no subie expert either, but thats just flat out retarded. The timing belt should be under the goddamned timing cover, and would absolutely not be attached to the alternator or other engine-driven accessories.

If the timing belt had let go, hed have a wrecked engine head, too.

by **albersondh** » Fri Feb 24, 2012 10:20 pm

His engine is a H4 2.0L. By deffinition the only serpintine belt it has is the timing belt. Yea there "should" be a complete plastic cover over the t-belt, good job pointing that out. I cant tell you how many cars I see with missing, cracked, bent or broken t-belt covers, that are years newer than the OP car. I covered the details about the interfearance motor stuff and implications of the possibility of a broken t-belt, thanks for the rehash. Didnt mention anything about the t-belt being attached to acsessories; so not sure where you got that from....

by **MaconCJ7** » Sat Feb 25, 2012 9:16 am

You do realize that the main belt that runs water pump, fan, alternator, etc on almost every car made since the early '90s is a serpentine belt right? The only relation a timing belt has to the accessory belt is that it's flat. A timing belt has teeth on it, to match the gears it runs on. The teeth keep it from slipping, because a timing belt slipping is bad. A serpentine belt does not. It has grooves that aid in strength, flexibility, and placement.

Two totally different belts, doing completely different jobs. He's replacing the serpentine belt, not the timing belt, though replacing it isn't a bad idea either.

As far as the engine, he's already said it was a DOHC. Being that it's Japanese spec, it's most likely a EJ20G, as noted by it being in a '95 WRX STI.

I am curious of your statement: "By definition the only serpentine belt it has is the timing belt" though. My thoughts on what a serpentine belt is could be misguided, and I'm never against learning new things.

by **albersondh** » Sun Feb 26, 2012 2:56 am

Most cars 90+ (or ever) are not H4's and layout is more conducive to running acsessories on a single serp-belt. Acsessoreis are much farther apart as opposed to H4/H6. One of the factors when identifying a true serpintine belt system is the use of an auto tensioner. This is required because the belt is typicaly very long (like the t-belt on the EJ series, that uses an auto tensioner). They are flat, wide, and typicaly have a low contact angle that is conducive to increasing acsessory servicable life. They drive multiple (if not all) acsessories.

The front of my EJ255 has two belts showing and neither have auto tensioners because they are very short and are not needed, a manual tensioning mechanism is good enough. I have only changed my t-belt twice on this car, and both times I replaced the pulleys and tensioner. I have lots of pics from the last time I did the job (08 USDM EJ255) and would be happy to help the OP through the process if he decides to go that route? This is what a bad EJ auto tensioner looks like:

All belts on my EJ255 are flat multi-groove style, like serpintine belts, but they are very short and have no auto tensioners. Unlike the VERY long t-belt that has an auto tensioner. Mine last swap:

To the OP I was trying to make a simple point and obviously did a terrible job, let me try again. If, IF, the belt you are refering to as a serpintine belt, can be verified as being your timing belt (shown above in blue), and its condition is suspect, it would be in your best interest to change it as soon as you can. I reccomend the Gates racing "blue" belts (like mine in the above pic) for EJ's, they come marked so resetting the belt in time with the cam gears is a breeze. PM me and I can e-mail you pics with a walk through or can post up here.

by **MaconCJ7** » Sun Feb 26, 2012 4:36 am

albersondh wrote:To the OP I was trying to make a simple point and obviously did a terrible job, let me try again. If, IF, the belt you are refering to as a serpintine belt, can be verified as being your timing belt (shown above in blue), and its condition is suspect, it would be in your best interest to change it as soon as you can. I reccomend the Gates racing "blue" belts (like mine in the above pic) for EJ's, they come marked so resetting the belt in time with the cam gears is a breeze. PM me and I can e-mail you pics with a walk through or can post up here.

That makes more sense. I think the confusion came from the OP issue being electrical, and you saying it's likely the timing belt. But, now that that's cleared up, I agree whole-heartily.

by **Kiwi Bowhunter** » Mon Feb 27, 2012 12:40 am

Please don't drive a car when the alternator belt isn't attached...
On most cars you will find that the same belt runs your water pump(and probably other stuff, too). You run it too long with no water pump your engine will steam itself.
And your temp gauge won't tell you shit, as there's no hot water moving out of the engine passing the temp sensor.
Especially on a Subaru, they seem to shit themselves for fun, so giving them an excuse to blow up is a bad idea.
My mate had one of those models, should be quad cam if it's an STI?(2 heads, 2 cams per head)
Could be wrong, I hate Subaru's so don't bother learning too much about 'em.
If you want a more permanent fix, buy a Toyota :wink:

Cheers,
Sean.

by **warlock4u** » Tue Feb 28, 2012 2:44 am

Especially on a Subaru, they seem to shit themselves for fun, so giving them an excuse to blow up is a bad idea.

IDK where you have been getting your cars, but I have never beat on a car with such fervor and malice as I do with my Subaru. The weak link in my particular model is the transmission, so I take care not to abuse it as much as I do EVERYTHING else. I have had quite the opposite experience as you have, and frankly so has just about everyone else I know. Maybe they re-brand Kia's as Subaru's down under?