Replace alternator pulley and sprag bearing or whole alternator?
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 323
Likes: 4
From: Los Angeles, CA. USA
2013 c250
Replace alternator pulley and sprag bearing or whole alternator?
So much misinformation out there! Just looking for the simple answer.
Chirping noise when in reverse. Everyone says 'watch out!' cuz it'll take out your A/C compressor. Great! I want the answer, just the answer. It seems like chirping is from a belt slipping due to alternator pulley either seized or too loose. So would replacing this $40 part fix the problem OR would you HAVE to then replace the sprag bearing or will the new alternator pulley compensate for any potential problems with the sprag bearing? It seems like once you start messing w/ replacing the sprag bearing, you may as well get a rebuilt alternator and just install that. BUT I DON'T WANNA! Seems like overkill.
Will a new alternator pulley fix the chirping and protect the A/C compressor from going out?
Chirping noise when in reverse. Everyone says 'watch out!' cuz it'll take out your A/C compressor. Great! I want the answer, just the answer. It seems like chirping is from a belt slipping due to alternator pulley either seized or too loose. So would replacing this $40 part fix the problem OR would you HAVE to then replace the sprag bearing or will the new alternator pulley compensate for any potential problems with the sprag bearing? It seems like once you start messing w/ replacing the sprag bearing, you may as well get a rebuilt alternator and just install that. BUT I DON'T WANNA! Seems like overkill.
Will a new alternator pulley fix the chirping and protect the A/C compressor from going out?
MBWorld Fanatic!
Joined: Sep 2011
Posts: 1,657
Likes: 35
From: Austin, TX
2005 C230K(sold), Mk7 Jetta
It will fix and protect.
However, you will probably end up paying about $150 in parts and tools to replace the pulley.
It seems that you have to remove the alt to swap the pulley.
Also, you don't know how much life is left in your voltage regulator.
Bottom line, I'd replace the alternator with a remanufactured one (which I actually did for about $200 total).
However, you will probably end up paying about $150 in parts and tools to replace the pulley.
It seems that you have to remove the alt to swap the pulley.
Also, you don't know how much life is left in your voltage regulator.
Bottom line, I'd replace the alternator with a remanufactured one (which I actually did for about $200 total).
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 323
Likes: 4
From: Los Angeles, CA. USA
2013 c250
91K miles. I already know what you're going to say. Yes, I'll replace the whole alternator IF the alternator pulley is seized or goes both ways (how I like my women!). I found a video that shows how to check the pulley with the alternator taken out (below), but I'm looking for the easiest way to do this, hence I don't want to take out the alternator. Is this possible? I understand from VVF that I'd need to remove a belt? Which one and how? Thx,
On second thought, screw that. IF the sprag bearing that everyone talks about that kills the a/c compressor is part of the alternator pulley, I'm just replacing that b/c it's only $40! So.. am I right? Is the sprag bearing within the altnerator pulley?
On second thought, screw that. IF the sprag bearing that everyone talks about that kills the a/c compressor is part of the alternator pulley, I'm just replacing that b/c it's only $40! So.. am I right? Is the sprag bearing within the altnerator pulley?
Last edited by scottonfire; Jun 26, 2014 at 10:21 PM.
MBWorld Fanatic!
Joined: Sep 2011
Posts: 1,657
Likes: 35
From: Austin, TX
2005 C230K(sold), Mk7 Jetta
IMHO mileage only indirectly correlates with the alt/VR/bearing failures.
More likely it's how many hours it has served you (i.e. 1 mile on the highway is not equal to 1 mile in a traffic jam)...
You don't have to "block the rotor" as in the video.
Just grab the pulley and turn it clockwise, and immediately yank it counterclockwise.
The inertia of the rotor should keep it rotating clockwise, and if the pulley is not seized, it will "slip".
If it's seized, it will feel like it's permanently bolted to the rotor when you are rotating it back and forth.
Yep, that sprag bearing is part of the overrun pulley, so you only need to change the pulley to get rid of the chirping.
PM Hogger on this forum, I think he might have the pulley removal tool as he did his pulley about a year ago (he ended up removing the alternator to replace the pulley).
Otherwise the tool costs about $70
This thread will be handy if you are not sure how to remove the belt (there's only one serpentine belt on M271 engines) -
https://mbworld.org/forums/c-class-w...t-attempt.html
You may skip the step with unbolting the silencer if you get a special "slim" wrench for belt tensioners from autozone(?).
More likely it's how many hours it has served you (i.e. 1 mile on the highway is not equal to 1 mile in a traffic jam)...
You don't have to "block the rotor" as in the video.
Just grab the pulley and turn it clockwise, and immediately yank it counterclockwise.
The inertia of the rotor should keep it rotating clockwise, and if the pulley is not seized, it will "slip".
If it's seized, it will feel like it's permanently bolted to the rotor when you are rotating it back and forth.
Yep, that sprag bearing is part of the overrun pulley, so you only need to change the pulley to get rid of the chirping.
PM Hogger on this forum, I think he might have the pulley removal tool as he did his pulley about a year ago (he ended up removing the alternator to replace the pulley).
Otherwise the tool costs about $70
This thread will be handy if you are not sure how to remove the belt (there's only one serpentine belt on M271 engines) -
https://mbworld.org/forums/c-class-w...t-attempt.html
You may skip the step with unbolting the silencer if you get a special "slim" wrench for belt tensioners from autozone(?).
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 323
Likes: 4
From: Los Angeles, CA. USA
2013 c250
IMHO mileage only indirectly correlates with the alt/VR/bearing failures.
More likely it's how many hours it has served you (i.e. 1 mile on the highway is not equal to 1 mile in a traffic jam)...
You don't have to "block the rotor" as in the video.
Just grab the pulley and turn it clockwise, and immediately yank it counterclockwise.
The inertia of the rotor should keep it rotating clockwise, and if the pulley is not seized, it will "slip".
If it's seized, it will feel like it's permanently bolted to the rotor when you are rotating it back and forth.
Yep, that sprag bearing is part of the overrun pulley, so you only need to change the pulley to get rid of the chirping.
PM Hogger on this forum, I think he might have the pulley removal tool as he did his pulley about a year ago (he ended up removing the alternator to replace the pulley).
Otherwise the tool costs about $70
This thread will be handy if you are not sure how to remove the belt (there's only one serpentine belt on M271 engines) -
https://mbworld.org/forums/c-class-w...t-attempt.html
You may skip the step with unbolting the silencer if you get a special "slim" wrench for belt tensioners from autozone(?).
More likely it's how many hours it has served you (i.e. 1 mile on the highway is not equal to 1 mile in a traffic jam)...
You don't have to "block the rotor" as in the video.
Just grab the pulley and turn it clockwise, and immediately yank it counterclockwise.
The inertia of the rotor should keep it rotating clockwise, and if the pulley is not seized, it will "slip".
If it's seized, it will feel like it's permanently bolted to the rotor when you are rotating it back and forth.
Yep, that sprag bearing is part of the overrun pulley, so you only need to change the pulley to get rid of the chirping.
PM Hogger on this forum, I think he might have the pulley removal tool as he did his pulley about a year ago (he ended up removing the alternator to replace the pulley).
Otherwise the tool costs about $70
This thread will be handy if you are not sure how to remove the belt (there's only one serpentine belt on M271 engines) -
https://mbworld.org/forums/c-class-w...t-attempt.html
You may skip the step with unbolting the silencer if you get a special "slim" wrench for belt tensioners from autozone(?).
Trending Topics
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 323
Likes: 4
From: Los Angeles, CA. USA
2013 c250
Okay, so it looks like all I need to do is rent some tools (auto zone or o'reilly's) for the alternator pulley. This video (starting at 3:20) says in neutral with car off, you can test it w/o taking off the belt. Not sure what it would look like if it 'slipped' since they don't show it.
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 323
Likes: 4
From: Los Angeles, CA. USA
2013 c250
rented an alternator pulley 'puller' and ordered an alternator pulley from pelican parts for $50. I'll probably need to also rent a belt tensioner tool to take off the serpentine belt, and I'll tackle it on Saturday. I haven't tested the alternator pulley BUT I HAVE to turn off the A/C in reverse otherwise that ****er squeals like a pig, so as long as I can replace the pulley w/o taking out the alternator (so I'm told), this seems like the easy fix.
MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
Scottonfire, what was the final result?
My belt has also been squeaking and chirping (especially bad when the AC is on) for years. My indie claims they can can remove/replace the belt and the alternator pulley for about 30 minutes of labour. Yeah it's not a hard job, but sourcing the proper tools is the hard part. One thing I did notice is that the OEM (Gates) belt has been getting really smooth (polished) on the non-ribbed side, to the point the lettering for the brand and belt model etc. is starting to come off. Meanwhile, the new Continental replacement one (7K2420) has a grippier knurled pattern on the non-ribbed side. Hoping this will solve the problem. The current belt actually still looks fine, but it's old enough to go to high school. And that squeaking is driving me nuts.
My belt has also been squeaking and chirping (especially bad when the AC is on) for years. My indie claims they can can remove/replace the belt and the alternator pulley for about 30 minutes of labour. Yeah it's not a hard job, but sourcing the proper tools is the hard part. One thing I did notice is that the OEM (Gates) belt has been getting really smooth (polished) on the non-ribbed side, to the point the lettering for the brand and belt model etc. is starting to come off. Meanwhile, the new Continental replacement one (7K2420) has a grippier knurled pattern on the non-ribbed side. Hoping this will solve the problem. The current belt actually still looks fine, but it's old enough to go to high school. And that squeaking is driving me nuts.
MBWorld Fanatic!
Joined: Sep 2011
Posts: 1,657
Likes: 35
From: Austin, TX
2005 C230K(sold), Mk7 Jetta
https://mbworld.org/forums/c-class-w...ditioning.html
30 minutes of labor? perhaps he is not planning to remove the supercharger silencer then?
Apparently it's not hard to find the alternator pulley tool, but it's much more rewarding to pay $60-70 to have it done for you. The tool alone probably costs that much.
30 minutes of labor? perhaps he is not planning to remove the supercharger silencer then?
Apparently it's not hard to find the alternator pulley tool, but it's much more rewarding to pay $60-70 to have it done for you. The tool alone probably costs that much.
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 323
Likes: 4
From: Los Angeles, CA. USA
2013 c250
Scottonfire, what was the final result?
My belt has also been squeaking and chirping (especially bad when the AC is on) for years. My indie claims they can can remove/replace the belt and the alternator pulley for about 30 minutes of labour. Yeah it's not a hard job, but sourcing the proper tools is the hard part. One thing I did notice is that the OEM (Gates) belt has been getting really smooth (polished) on the non-ribbed side, to the point the lettering for the brand and belt model etc. is starting to come off. Meanwhile, the new Continental replacement one (7K2420) has a grippier knurled pattern on the non-ribbed side. Hoping this will solve the problem. The current belt actually still looks fine, but it's old enough to go to high school. And that squeaking is driving me nuts.
My belt has also been squeaking and chirping (especially bad when the AC is on) for years. My indie claims they can can remove/replace the belt and the alternator pulley for about 30 minutes of labour. Yeah it's not a hard job, but sourcing the proper tools is the hard part. One thing I did notice is that the OEM (Gates) belt has been getting really smooth (polished) on the non-ribbed side, to the point the lettering for the brand and belt model etc. is starting to come off. Meanwhile, the new Continental replacement one (7K2420) has a grippier knurled pattern on the non-ribbed side. Hoping this will solve the problem. The current belt actually still looks fine, but it's old enough to go to high school. And that squeaking is driving me nuts.
Newbie
Joined: Sep 2018
Posts: 12
Likes: 1
From: Toronto (Mississauga) Canada
2006 SL 65 Renntech
Maybach 57 Alternator rebuild install
Has anyone rebuilt and installed an alternator in a Maybach 57? At $12,000 for an alternator at the dealer it’s like owning a RR Silver Ghost.
I hear of alternator rebuilds for a few hundred bucks but the only one I see is $7200 on eBay. No, not the same as the other S-Class V12’s because they are 600 amps or something and water cooled. And I am told there is some special electrical reset that needs to be done
by the dealer after reset. Great cars, but parts are really just stupid. I think MB is trying to recoup their lost 100 Mill on parts alone.
Much appreciate any assistance.
I hear of alternator rebuilds for a few hundred bucks but the only one I see is $7200 on eBay. No, not the same as the other S-Class V12’s because they are 600 amps or something and water cooled. And I am told there is some special electrical reset that needs to be done
by the dealer after reset. Great cars, but parts are really just stupid. I think MB is trying to recoup their lost 100 Mill on parts alone.
Much appreciate any assistance.
MBWorld Fanatic!
Joined: May 2017
Posts: 2,290
Likes: 434
C320
Has anyone rebuilt and installed an alternator in a Maybach 57? At $12,000 for an alternator at the dealer it’s like owning a RR Silver Ghost.
I hear of alternator rebuilds for a few hundred bucks but the only one I see is $7200 on eBay. No, not the same as the other S-Class V12’s because they are 600 amps or something and water cooled. And I am told there is some special electrical reset that needs to be done
by the dealer after reset. Great cars, but parts are really just stupid. I think MB is trying to recoup their lost 100 Mill on parts alone.
Much appreciate any assistance.
I hear of alternator rebuilds for a few hundred bucks but the only one I see is $7200 on eBay. No, not the same as the other S-Class V12’s because they are 600 amps or something and water cooled. And I am told there is some special electrical reset that needs to be done
by the dealer after reset. Great cars, but parts are really just stupid. I think MB is trying to recoup their lost 100 Mill on parts alone.
Much appreciate any assistance.
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
