esixtyone

I noticed an odd noise about a week ago and a slight odd smell. Then shortly after leaving work I noticed the smell got really bad. I pulled over and there was smoke coming from the general area of the oil filter housing. It doesn't smell like oil and the oil level is good, maybe more of a slight rubber/plastic/electrical kind of scent. I had the car towed to a mechanic and they didn't see any issue other than the alternator putting out 16 volts. They replaced the alternator.

Yesterday after about 40 minutes of driving I noticed the odd noise I had before. No noticeable smoke this time. Your thoughts?

scottalexander

My guess is the bearing in the tensioner is acting up (belt tensioner).

The noise is louder at the belt tensioner verses the idler pulley

Let's start with:

- how many miles are on the car since the tensioner was replaced? Was it ever replaced?
- how old is the serpentine belt?

By the way, your new alternator looks nice. I would have just replaced the voltage regulator for $35.

esixtyone

Thanks for your reply.

Ugh on the voltage regulator. I'm always learning something new with these cars.

The serpentine belt is 15,000 miles old, replaced at a dealer. Is it standard to replace the tensioner at the same time? If not, the tensioner is likely original.

scottalexander

If the dealer replaced the serpentine belt, its likely they also replaced the tensioner at the same time (they should have, let's put it that way). Check your receipt for what they performed.

I change the belt, the tensioner and idler pulley at the same time (but that's me).

I looked at your video again and I see there is a bunch of dirt in and around the belt tensioner pulley. Maybe your streets are dirty, but tensioner doesn't look like that and its 3 years old.

Check your dealer receipt or call them and see if they changed the tensioner.

seanjordan20

Spray some wd40 or something that can line it up behind that belt tensioner pulley then start your car to see if it makes a difference

tstiglich

After watching the video, it looks like there is a lot of movement in your tensioner. Don't know if that is normal or not. If you are a DIY sort of guy, I would remove the belt and spin each of the pulleys. My thought is that one of the pulleys might be bad, which would cause noise and may result in a sort of pulsation of the belt tension.

esixtyone

I found out the tensioner was replaced with the serpentine belt at 65K miles which was 15K miles ago.

I thought the tensioner pulley seemed to be moving quite a bit too and was wondering if it's normal. I took a look at my 535 and it moved a bit too, though not quite as much.

scottalexander

Ok, looks like you have a new tensioner. Its unlikely it would go bad in 15,000 miles (but who knows).

When the shop installed your new alternator they would have had to remove the serpentine belt.

Did they damage the tensioner when they removed it?

In order to do that job properly, you need a #60 torx socket to adjust the tensioner and remove the serpentine belt.

If the mechanic didn't have one and used a pry bar, they could have damaged the tensioner.

Here's the quick test.

Remove the belt.

Spin the tensioner pulley by hand.

Does it spin fast and whizzzzzzzz around fast?

When the tensioner pulley or idler pulley are new, and you try to spin them by hand, they don't spin. The bearing is nice and tight.

esixtyone

Update: mechanic replaced the idler pulley that attaches to the alternator, and replaced the belt tensioner and tensioner pulley.

Noise and smell are still there. 😡

Haven’t seen any smoking from the area since I first had car towed to mechanic; so no smoking since alternator was replaced.

Car at is going back to the mechanic tomorrow morning. At this point seems maybe the rebuilt alternator is bad if you ask me.

Also, I used a stethoscope to compare the noise between this and my N54 535. The 528 alternator sounds significantly harsher through the stethoscope.

scottalexander

Here's another guess.Your mechanic replaced the alternator and pulleys. They obviously had to take off the serpentine belt.



Here comes the guess:



The mechanic put the serpentine belt back on in the opposite direction from which they took it off. The wear patterns were in the opposite direction.



I always put an arrow on my belt before I take it off so it goes back on in the proper direction which it is wearing.