JasonDowney

iTrader: (1)

The past couple weeks I have noticed that a squeeking sound was comming from under the hood. Couldn't figure out which belt it was untill about a week ago when I started smelling burn rubber, and shortly after the alternator belt broke. So I took out the alternator and dissasembled it, but noticed nothing wrong with it. Just in case, I bought another alternator(these were from fd's btw). Since the second alternator I got had some marks on the rotor, I used the rotor from my old alternator. Also, I kept the bearings on as they seemed smoother. I put it back on and it ran fine untill a day later, and it started doing the exact same thing. What exactly could cause this? There doesn't seem to be any pattern to it, besides that it will only lock up in the lower rpms, and it would usually go away after shifting(rpms decreasing). Is there anything that could cause this?

dizflyaznboi

do you have the airpump removed? If so do you have two belts going on the alternator and the water pump, if not that might be your problem.

JasonDowney

iTrader: (1)

I don't have the airpump removed. Is it necessary to have a dual belt setup? The only extra load I have on the electrical system is the audio stuff, and the symptoms still occur when the speakers are not in use.

helghast7

iTrader: (6)

theres always the wallet painful (well to some) thought that you need a new alternator...i no i do...but not for the same reason...for flamming sake i wont go into it

JasonDowney

iTrader: (1)

The thing is, I just bought this alternator. Both alternators(both fd alt.) have exhibited the same problems. The only items reused in the alternator were the bearings and rotor, which I couldnt see being the problem.

JasonDowney

iTrader: (1)

Another alternator belt broke on me from the alternator locking up. Is there anything else that could cause this?

so-mars

uhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh h

what the hell else would it be if it wasnt the moving parts?

are you high? lol

*points at the metal enclosure and says 'metal bad! wood good!'*

JasonDowney

iTrader: (1)

except for the fact that nothing appears wrong with the rotor or the bearings, they both spin freely. Before I got into cars, I was being into electric motors, which alternators basically are. Therefore I know a good bearing from a bad one, and I also know that unless the rotor was deformed, it would not prevent the alternator from rotating.

How tight should the alternator belt be?

Suiicidalpenguin

Should be taught but not uber tight (basically tight enough you can't move it alot but not so that its ready to peel away the pulley). Also since you smell burning have you checked all around where the belt moves? Mayble something is rubbing against the belt elsewhere?

JasonDowney

iTrader: (1)

The burning smell is from the alternator belt rubbing against the pulley. I am sure of this since it has not only darkened the anodized coting, but it has also gotten it hot enough to deform it.

so-mars

yeh my thought is

1) the other wheel that the belt is attached to
2) you didn't use a crowbar/lever underneath it to install it (jacked all/most the way up the slot)
3) improper angle line-up on the two wheels if refurbished/different alternator
4) what he said... two belts rubbing against each other... which would probably mean loose belt.

if it wobbles thats no good

i seem to go through alternator belts a bit too much myself but i might have fixed it this time by bending the slotted arm out a bit so my 'new' non-original spec alternator lines up better (the plastic wheel was about 1/4" to 1/2" more inward)

so-mars

or in this case maybe too tight and not right angle

you really gotta seat the thing in there perfectly and watch it run

JasonDowney

iTrader: (1)

I didnt use anything to pry it up while installing it as I didnt know the belt had to be that tight.

For your second post, if it was too tight, I would think that the alternator wouldnt stall as much since the extra force against the pulley results in more friction and hence more power applied to the alternator. But I could be wrong

so-mars

ahh see its kind of tricky its not necessarily the 'tightness' so much as the angle, i'm no physics expert but you can get the belt itself pretty tight w/o having the alternator jacked up high enough so yeh its somewhat of a torque thing and not strictly pressure. i guess that makes it 2 dimensional instead of 1 or something i dunno hehe. just stick a curved flat crowbar end type thing under the alternator and lift up so when you attach the bolt its pretty high up on that long slot.

but there's also the horizontal line-up on the wheels if you are looking straight down at the belt if you have a remanufactured alternator like mine is that is just slightly off original spec so looking straight down the belt is slightly diagonal, fixed that by bending the arm out a bit with a hammer heh.

so-mars

these aren't the best pics coz its with mobile phone... and my alternator belt broke RIGHT before my coils died and i fixed it in the parking lot so i havent had the time to install it right because looking at these pics im like... oops. lol. i didn't have a lever thing on me so the bolt is way too low on that slot.

JasonDowney

iTrader: (1)

Ill try having the belt a bit tighter and see if that helps. :crossed fingers: Since it was an fd alternator, I was using a non-stock pulley, which appears to be of a smaller diameter than the one pictured above.

Also, is there a method to taking off the bolt holding on to the pulley?

TehMonkay

iTrader: (-1)

Impact wrench.

Try getting the car completely warm, come back home, loosen the belt and start the car (I mean really loose) and see if the pulley will spin, or if it spins for a while, then stops, thats what the bad alternator in my GFs scirocco does. It doesn't appear to be siezed until it's warmed up.

so-mars

yeh i dont know if this is your problem and i know you have different gear (this is an 89 FC3S5 automatic non-turbo)

you can't really see where the two wheels didnt line up because i've already bent the install arm out a little bit to get it to line up better, but can probably notice the alternator is slightly different



and the slot on the arm i mean its blatantly obvious i didnt put it in right... i changed the belt in a freakin parking lot at advanced auto after the old one was hanging by like 2mm worth of threads and amazingly still working lol

RotaMan99

When I was installing my 2nd FD alt, I noticed the pulley I had that is machined for the FD shaft, would lock up against the front housing of the alt. Obveously I noticed this right after putting the pulley on.

Maybe your pulley is rubbing on the housing enough to cause extra drag?

JasonDowney

iTrader: (1)

RotaMan- I also thought that could be the problem, but that would cause a constant drag. The problem I experienced was intermitent.

TehMonkey- that would make sense, but this happens even seconds after start-up, which means there is not enough time for it to heat up.

SpeedOfLife

iTrader: (16)

I recently had an alternator burning the belt and it was seizing up almost exactly like you described (at lower RPM and such). You really should replace the whole alternator, I don't see why you thought you could reuse the rotor and bearing, one of those two things are almost certainly what went bad. Also, I had my old alternator tested on an in-store rig and we couldn't get it to lock up in the store, but as soon as it went back on the car it would.

JasonDowney

iTrader: (1)

Thanks for the info. I would have replaced the whole alternator except a forum member here, mmonaco, sold me an alternator that had apparently had something caught inside as its fins were all mangled. Hopefully it is just the bearing that was seizing up since I cant think of a reason that the rotor would cause it to lock up like it did.

SpeedOfLife

iTrader: (16)

I recently learned that alternators, after being used for many miles/years, can begin to pull the internal coils apart. Not by much, but it can be enough to catch on something and seize (some alt's are more prone to this than others, but since 7's can rev higher it might happen more than we realize).

JasonDowney

iTrader: (1)

I just finished installing a third alternator and it too burnt a belt. I also tried putting more tension on the belt this time, and it just seemed to fry it more quickly. Any other problems that i should be looking for?

JasonDowney

iTrader: (1)

I now know that the problem is due to an abnormally high current draw. When the lights are up, it causes the belt to squeek; same with the radio. Now, next step. What could cause this high current draw? I looked in the fuse box and I noticed that the main fuse was discolored, which is usually a sign of high heat(due to high current). Any suggestions?