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Noisy alternators

3K views 13 replies 4 participants last post by  choch345 
#1 ·
I have had two of these, my 02' and 07' Dodge, GC.
I replaced the 02, 3.3L with a remanufactured one and that took care of noise but the 07' 3.8L is more complicated, I'd have to drain some coolant I believe to get it out. Line is in the way.
I've heard other Caravans doing the same thing.
What is it in the back of the alternator that is making this noise? It's not the bearing.
It's a pulsating noise/rattle that makes you think it's the A/C compressor, but it's not.
 
#4 ·
The alternators pull the same way between both engines. You do not need to drain any coolant. The 3.8 is more likely to have an EGR valve where the 3.3 likely didn't. You do need to remove the EGR valve if it's equipped. The lower bolt is a bitch to remove off the EGR valve. I suggest an 8mm ¼" drive swivel socket and a short extension for that lower bolt. I really, really, really doubt that the noise you're hearing is actually in the back of the alternator. The decoupler is probably transferring noise through the alternator. Put your stethoscope on the alternator case just above the pulley and it'll likely get louder yet when you're listening to it.
 
#5 ·
It's most definitely coming from the rear plastic cover area at the back end of the alternator.
Everything else is relatively smooth and quite.

Now if that tube is an EGR circuit then I won't mind taking it loose. I just didn't want to mess with the coolant.

It's easier to just replace the alternator than to fix it although it is expensive just for noise.
 
#8 ·
It reduces vibration at or near idle. The mechanic that I used to use installed an alternator without the clutch and it was immediately noticeable after I left the shop. Note I said that I used to use that mechanic.
 
#9 ·
I'm giving up on this alternator* for the time* being.
The noise is most definitely coming* from* the* alternator but I can't determine if it's the decoupler or the alternator.

Test#1, I ran the engine* at 2500 rpm and shut* it off abruptly but didn't get any noise.
Test 2 and 3 couldn't be performed because I have been unable* to find the* correct* tools and there is no room to use them if I did.
I would have to remove the alternator to test the decoupler and if it was found to be good, then I wouldn't* have a new* dust* cap to replace the old one (single use).
A new decoupler runs about $75.00, less my discount and if I just install a new alternator with a new decoupler already* on it, it's about* $180.00, less my discount.
So that's kind of steep for a noise that doesn't* seem* to hurt anything but my ears and pride.
Good thing* I could* change it myself instead of also paying labor too.
If I knew for sure it was the decoupler I would change it and be done with it.
Ah, such is life.
 
#13 ·
I went to Harbor Freight and bought a serpentine belt tool set,$17.00.
Then I ordered the decoupler tool kit from Amazon, $26.10.
We have 5 of these vans in the family so I figure it's worth it.

Then I loosened the clamp on the intake connector and opened the air filter box, disconnected the wire to the sensor and set it aside.
Then I removed the two screws holding the air filter box in place, 8mm I think, and set the air box aside.
This gives you room to work on the decoupler.

I jacked up the right side of the van a little way to give me room to get under it and work.

There is a plastic splash shield held on by some plastic push pins that need to be removed so you can get at the tensioner to loosen the serpentine belt. Take the belt off of the A/C pulley and slowly let go of the tensioner.

Now, go back on top and remove the dust cap on the end of the decoupler pulley with a knife blade.
Insert the 10mm decoupler tool and then the hex adapter that fits the pulley.

Now you will have to manuvour a breaker bar with an 11mm socket for the center tool and a 3/4" combo wrench for the pulley tool and loosen the decoupler from the alternator shaft, it's right handed thread. Loosen it and turn it off.
Turn the new one on and tighten to 50 ft.lbs or good and tight if you don't have a torque wrench.

Now put it all back together.
 
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