70 amp is standard, 80 amp is optional... not sure if they're swappable... I would imagine they are. CARQUEST has the 70 amp for $160, 80 amp for $150ish

 

I also had a 1990 2VZ-FE and I have to put a new alternator in it. My car was an LE, power everything, and it had the 70 amp in it. There wouldn't be a negative affect from puttin the 80 amp in. Everything should be fused and this it what will keep it safe. Unless you have a bunch of extra electronics on the car you shouldn't need it. Besides I tryed to fit the 80 amp in my car, and it didn't work. It was about the same size but I remember the 80 doesn't have the same indent as the 70 and it was hitting some thing on one of the mounting brackets.

I would get one from and auto parts store, I like advanced auto, if there is one near you. Get the life time and you won't have to worry about it again.

I never heard of a bad alternator affecting gas mileage, but it is possible. It would be an extra load on the engine.

 

Remove the belt and with your hand see if the alternator pulley spins freely. It probably will. If that's the case, the gas mileage problem isn't with your alternator. I would leave the alternator alone until it shows some other sign of it really going. If you are concerned about it's output, you might want to reinstall the belt and check the output with a DVM or take the car to a parts store in your area that does on car testing of the charging system for free.

Then look for other sources for you decreased fuel mileage. A good place to start would be to check for any engine trouble codes. If nothing shows up there, next jack up each wheel seperately and check for a bit of brake drag. If nothing shows up with the brakes, I would next check the engine coolant temperature sensor with a DVM and the specs from any manual, for being out of spec. If you still don't find anything, I would change out the thermostat. The thermostat could be opening late or be stuck in the open position causing engine warmup to be delayed. This results in the car running a richer than normal mixture during this extended warmup period.

Mike

 

That is a pretty big drop in MPG for an alternator issue.

 

here's another symptom of my car which is why i assume the alternator is about to go.

Driving down a steep hill, i shift to neutral and just coast [assuming lower RPM's = less gas used]; the last couple of times i did it, the power cut out and i had to restart the engine mid-coast.

also, the CEL would come on periodically for a few miles and disappear.

DVM test on battery reads 12.73V so battery isn't an issue.

haven't done DVM test on Alternator yet as both Haynes and Chiltons aren't very clear on how to do this.

I did take a stethoscope to the alternator and have isolated the hum to the alternator. Also, the first time i noticed the hum, when i opened the hood, i smelled a burning smell like burning electronics...

I'll drop by autozone in a few minutes to have my charging system tested.

and after reading several posts on the EGR, i have a feeling my sudden drop in mileage may be due to EGR.

 

a plugged up egr might make it ping and mpg might get better, not the other way around

 

"also, the CEL would come on periodically for a few miles and disappear."


If that's the case, read the code(s). I will give you a starting point.

Mike

 

Maybe you have a bad ground or power lead to something that is intermittently drawing a ton of current to function, which would cause the alternator to possibly hum even if the bearings are fine.
Just a thought, maybe you can use an ammeter while the humming goes on and see what is being drawn.

 

VIN will tell you if it is 70A or 80A.

I paid $140 for a remanufactured Toyota/Denso alternator with 1 yr warranty from the dealer. (plus $30 core charge - which they refunded).

You will need a hammer or mallet and screwdriver/pile to push back the sliding washer sleeve or the new alternator will not fit into the old space.

if it's an OEM reman, shouldn't it fit?

 

The alternator housing is a somewhat imprecise casting, and the part being moved is a bushing that makes up for this lack of precision. Many alternator mounting schemes use this type of bushing.

 

I'm with Mike. Unless the alternator pulley is hard to turn it wouldn't have any effect on the gas milage. If your battery is maintaining a charge then the alternator is probably OK. The autozone check will be interesting.

If the engine died from lack of electricity while coasting (assuming a dead battery because the alternator wasn't charging it) you wouldn't be able to crank the engine midway down the hill because there wouldn't be any electricity left in the battery.

If I recall, a clogged IAC valve might account for the car dieing while coasting down a hill. It might also have a negative effect on your milage.

Next time you get a check engine light try to pull over. Don't stop the engine (so the CEL doesn't go off) and check your CEL codes.

Kep

 

The alternator housing is a somewhat imprecise casting, and the part being moved is a bushing that makes up for this lack of precision. Many alternator mounting schemes use this type of bushing.

I had this problem years ago when replacing the alternator on an old 86 Camry I owned. The new alternator wouldn't fit down in to it's bracket. The bushing was out too far. It took me a while to figure out a solution. I found a hex bolt and matching hex nut just a bit smaller than the opening. I screwed the nut down on the bolt and then placed the assembly in the opening for the alternator in it's bracket. I used 2 wrenches to unscrew the nut from the bolt, forcing the bushing back far enough for the alternator to fit in it's bracket. I was very proud of myself after it worked.

Mike

 

I had this problem years ago when replacing the alternator ... I found a hex bolt and matching hex nut just a bit smaller than the opening. I screwed the nut down on the bolt and then placed the assembly in the opening for the alternator in it's bracket. I used 2 wrenches to unscrew the nut from the bolt, forcing the bushing back far enough for the alternator to fit in it's bracket. I was very proud of myself after it worked.

I had that issue on my Celica... I used a hammer (yikes!) !!

 

A couple of gentle taps on the bushing are usually more than enough to move it, using a small hammer.

 

A couple of gentle taps on the bushing are usually more than enough to move it, using a small hammer.

I was never able to get a hammer in there to tap it. There was just not enough room. I even tried turning the hammer sideways, but then there was still not enough room to get any leverage at all. Oh well, it worked out.

Mike

 

ok, autozone couldn't successfully perform the test, so i took my car to Kragen.

according to their test equipment, my car isn't charging the battery, most likely due to a bad alternator. The interesting thing is...they never touched the alternator.

I'm goin to figure out what the haynes manual is saying and test the alt myself.

 

ok, i just did a CEL diagnostic test, and i have a codes 25, 26, and 71

that could be what's causing my huge gas mileage drop.

But, i'm still concerned about Kragen said about my charging system not charging the battery.

 

You don't need to "touch" the alternator to test it.

 

You don't need to "touch" the alternator to test it.

+1

all you need for an alternator test is a multimeter connected to the battery and someone to start the car

also, according to my chilton's engine code manual these are your problems:

25: air/fuel mixture too LEAN
26: air/fuel mixture too RICH
71: EGR system malfunction

how you're getting a mixture that is simultaneously too lean AND too rich can be most probably blamed on a bad O2 sensor sending bad signals at different times. A bad EGR valve is a bad EGR valve...

 

I'm with the others, the alternator will not have a significant affect on gas mileage. If the alternator is going out you will have other issues that will surely catch your attention first and not likely a drop in mpg is going to be one of the symptoms. I'va had altnernators do a slow fade and this can cause loss of power and an engine miss at higher speeds (or at all speeds). And note that if the alternator is slowly failing, sometimes the alternator light will come on and sometimes it!

 

after a day and a half! [mostly due to not having proper tools] i finally got the old alternator out and the new alternator in!!! now i have that wonderful feeling of having completed a big job on my own!!! ^_^

the unusually loud hum from the passenger cabin is now gone. One thing that should have tipped me off, was when i insert the key into the ignition, the battery light should have lit up. it wasn't lighting up before the alternator change. Now it does ^_^

next task, reset the the ODB and get the CEL to light again. But first:

my car now has a rough idle [vibration]. Do i just need to tighten the belt more?

 

Unless you know the belt is too loose, don't tighten it.

A rough idle is a separate matter. Lifespan on wires is about three to four years for a toyota, and they are dated from the factory. I'd pull the plugs and have a look for starters. Check the spec for the plugs, and compare the measurment to a feeler gauge for plugs.

 

i don't have a belt tension guage, so i don't know whether or not it's loose or too tight. basically, i just pressed down on the belt. if it gave in too much, i tightened it a bit.

 

I do it by feel (I also have a torque wrench built into my arm) but if you have around 3/8 or 1/2 inch deflection in the middle, you should be okay.