matrix11229

My old alternator was whining and wasn't charging the battery so well, but my brake and battery lights were off.

Today I went to mechanic to replace the alternator with a remanufactured one, and after I spent the whole day there they finally installed it. Also we put new ps and alternator belts that I bought at the dealership.

I turned on the engine and they checked the volts and it was perfect 14v even with lights and defroster on.

Then I moved my car out to the parking lot there, and replaced my coolant temperature sensor. So I turned on the engine and I see the battery and brake light on , sometimes they were flickering and turning off and then on again.
The mechanic checked the volts again and it was 12.6 or 12.9, and he said it's not charging the battery.

They were closing already so I left the car there and they gonna put a different alternator tomorrow.

I don't know why it happened, the coolant temperature sensor has no effect on the alternator. I suspect they damaged the alternator harness.

matrix11229

Finally the alternator was replaced today , and the volts are at 14.1 , and no more flickering brake/battery lights.
My mechanic told me that he didn't apply too much tension on the belts, he said it's better this way .

But now I feel a very slight vibration in idle and the rpm gauge arrow goes up and down a little bit in idle (P or N) , it's hard to see but it's there. It jumps approximately 50 rpm up and down.

May be there is not enough tension on the belts ?
Also my horn sounds weak now, not a usual sound.

I'm gonna go back to the mechanic tomorrow.

Any ideas/suggestions ?

sam29281

never go there again! for someone who works day in and out on cars...that is pathethic worksmanship. This one mechanic put on my belt backward..inside out. I drove it off and the pulley fell somewhere onto the street. Luckily it was only a few blocks from where the mechanic shop was. took him a week to put it back together.

I got pissed. I uninstalled the belt and redid his work. I swear...where do these people get their license and training!

BobK

I would guess the idle changing has been there and you just haven't noticed or the computer codes being cleared while the battery was unplugged.

It's not uncommon to get a bad rebuild, it's happened to me on a number of occasions. Some are good for a couple of days before they start having problems... I put 3 in an old Toyota truck one time in a span of about 2 months (lifetime warranty) the third seemed fine and we drove a couple of hundred miles on a vacation, it ends up going bad. Had to have it towed to a shop and after a couple of hours testing they dedide it is the altenator and they replace it for "only" $300. Well about a month later it goes out again... give them a call and they told me they bought the alternator at O'rielly Auto (the same place I had bought mine), I also found out about mark-up knowing that they only payed $90 for the alternator but charged me $186 for parts. Well I got their parts store to call my local store so I could pick up a replacement... put in that one and it's been in there for the last 8 years. The parts guy at O'Riellys told me they had got some really bad batches around that time. Last year when I replaced one on a Ford truck the first replacement was bad right out of the box, didn't charge at all. Now whenever I buy a rebuilt alternator I make sure the test it before I leave the store.

Point being don't jump to conclusions about the mechanic yet, it's pretty hard to screw up replacing the alternator. More than likely it was just a bad part.

matrix11229

I'm sure the slight idle jupms were not there before. Also the computer codes didn't clear because I had CEL on Evap system before, and after they disconnected the battery and reconnected it the CEL turned on immediately.