Hi Guys,

This is my first post, despite being a member for a couple years now. That’s due primarily to the awesome pool of knowledge (and valuable search feature) at this website. Literally every time I have come here with a problem, I began by searching and ended up locating the answer without ever needing to post the question. I’ve been able to perform numerous repairs, retrofits, and upgrades. It’s incredible how many problems and symptoms are common.

Today I have a problem that I think is common, but I’m having trouble definitively diagnosing and resolving it. I have an annoying rattling sound coming from one of the accessories at low rpm (basically only at idle, and just off idle when letting out the clutch to drive away in reverse or first). The lower the RPM’s dip, the louder and more prounounced the rattle gets.

When I operate the car with the serpentine belt removed, it completely goes away (which is good news, since at least that means it’s not anything internal to the engine). Then with the belt off, I checked all the pulleys, and they all seem tight (no wobble) and spinning quietly and smoothly. With the belt back on, I have a good mechanics stethoscope and the rattle sounds strongest at the belt tensioner.

How can I definitively conclude which of the following is my problem:
1 - The tensioner assembly (the type with the damper piston) has gone bad.
2 – Or the tensioner is fine, but the pulley bearing is bad and needs to be replaced.
3 – Or perhaps some other pulley bearing (idler, water pump, etc.) is actually bad.

Please let me know your thoughts and suggestions.

Thanks very much,

Mark in North Atlanta.

2004 Chrysler Crossfire Coupe – Six Speed – ~127k miles.
Owned for two years – Completely stock except for stereo.

 

So no one has any suggestions for this one?

Someone must have some ideas for what to try next...

I guess I can try replacing the tensioner pulley first.

Thanks!

 

Remove the belt and spin the tensioner pulley by hand. If its smooth and offers very slight resistance then its good. If it spins very freely or has a lot of resistance with spots where it tries to stop randomly then its a good idea to replace it.

 

Okay, I have the T50H (tamper proof) drive to remove the pulley, but I can't seem to find anyone selling just the pulley itself. Many places have the entire tensioner assembly available, but not the individual pulley.

There seems to be a good bit of confusion (on the parts sites) between the tensioner pulley and the idler pulley, with both descriptions being used interchangeably and substituted for each other. I understand they may be the same on later SC equipped models, but on my 2004, these two pulleys are definitely different.

So does anyone know of a good source for a stock, non-ribbed, early NA tensioner pulley, or perhaps have a specific part number handy that might help me search further to locate one?

Thanks very much.

 

Auto Parts - Parts.com, For Every Part of Your Life
Try this.
http://www.majormotorshotrods.com/_d...ts_Catalog.pdf

 

Thanks, but both of those links show exactly the same thing I was referring to.
They both give a part number for the tensioner assembly, but not the individual pulley.

After some further searching I have located this replacement part: REPM317402.
And there are a number of very reasonably priced sources for this pulley ($15 shipped).

So I have ordered one of these, and will let you know if it silences my rattling noise.
Thanks.

 

You can find the entire tensioner assembly at RockAuto Auto Parts
look under Mercedes c320 - a lot cheaper for the MB than the XF.

There is also some handy info on it there :
Pulley Width: 26mm; Bearing ID: 17mm; Bearing OD: 90mm

 

Thanks, Mark.
OP can get it at Auto Parts and Accessories Catalog
for $25 shipped .....

 

Okay, the REPM317402 pulley is NOT the correct pulley for the tensioner on my 2004 model.

It is identical in every way, except its outer diameter (69mm) is smaller than the one currently installed on my car (97mm).

I removed mine (using the T50H torx drive) to see if there are any identifying numbers on it, and there are not.

Both pulleys have numbers molded in that identify the plastic content (PA66 GF50), but no automotive part numbers.

The bearings appear identical. The new pulley says “NGBC 6203RS”, and the bearing in my old pulley says “NTN 6203HA”.

I tried to install the new pulley just to see if had any effect on the noise, but it contacts the casting, so I couldn't even test it.

My current pulley is symmetric, so I reinstalled it backwards to see if that changed the noise, but it sounds about the same.

So I am back at square one on this problem, and still searching for the tensioner pulley...

 

Try RockAuto Auto Parts under Mercedes Benz 2003 C320
They have the assembly for $50.79
They also have the idler pulley at $12.03
and a Goodyear belt at $15.07

 

Yeah. EVERYONE sells the idler pulley, but yet NO ONE sells the tensioner pulley.

So it appears I must replace the entire tensioner, or just continue to live with the noise.
That's a bummer, since the tensioner itself is working fine, and performing it's job properly.

A Related Question:
My current tensioner is the type with the damper piston as part of the assembly.
So would I replace it with one of the newer style ones that doesn't include the piston..?

 

I really don't think it makes a difference. My 2005 has the coil spring one.