Supercharger drive belt idler pulley. Replace $540. Rebuild $27.
I only run pulleys, bearings, and belts for a maximum of 60,000 miles, then replace whether needed or not. I tend to be preventive maintenance inclined rather that wait for a failure on the side of the road. I regularly take a road trip of 850 kilometers one-way and at one point the nearest Mercedes parts suppliers are literally 290 kilometers behind me and 290 kilometers in front of me. That would not be a good place to break down, especially during a winter ice storm (last one I made the mistake of driving in it took me 7 hours to cover 120 miles and I counted 27 vehicles in the ditches before I just gave up and sought shelter)
First set was a Dayco serpentine belt tensioner (89335) and Febi supercharger belt tensioner (36981). Serpentine belt idler pulley was a Febi 36931. Dayco supercharger idler pulley was a 89012 (should have used the 89130) plus the NSK 6203ZZC3.
Second set installed at 150K miles: serpentine belt using a Febi 15875 tensioner plus Febi 44977 idler pulley. Supercharger drive belt was a Dayco 89130 plus the 6203ZZC3 bearing in the idler pulley plus Febi 36981 tensioner pulley ($220 from FCP Euro).
Using the Dayco 89130 plus the new bearing only cost me about $25. I'll rework the supercharger idler pulley again at 338,000 km rather than spend hundreds of dollars on a replacement. Don't cheap out on the bearing; only go for a quality one as the $3 cheap bearings will throw out the grease within days.
I see no reason you cannot find a Febi equivalent to the Dayco 89130. Those specifications are:
-diameter 90mm
-width 26.2 mm
-flange yes
-belt width 6-rib
-bearing ID 17mm
https://www.gates.com/us/en/power-tr...803-01019.html
The width of the steel 36157 mentioned above seems a little too thick (31mm), although its the one listed on the parts exchange.
Last edited by Kash_k; Jun 8, 2020 at 06:15 PM.




I'm leaning towards just buying the metal one listed on amazon by ACDelco. Will replace the 6203ZZC3 bearings also. $50usd gamble.
Does anyone know how to separate the 2 pulleys?






(Left the one mentioned in this thread, right the existing bearing)
Does anyone know the correct replacement bearing?
The Best of Mercedes & AMG
The approach I have assumed is that both tensioners are in good shape and all that is needed is an update to the pulley bearings. You should make sure the tensioner has a consistent tension as you lever it through its arc of range. Any noise, catches, roughness, or change in the smoothness of the arc is reason to replace the entire tensioner.
The engine has two serpentine belts - a regular belt that drives the alternator, A/C compressor, PS pump, and all the other components except the SC. The SC belt only drives the SC. That belt is wider than the typical and the regular serpentine belt.
The current cost of the tensioners and idlers from MB is more than $1,400. If you order them from a MB online dealer you can get that cost down by about 25% or so (down to about $1,100). Aftermarket components are a much lower cost option and if you follow these steps you can keep the cost below $75.
There are two tensioners. The regular belt tension has a plastic pulley so replacing the bearing in that pulley is not an option as the bearing is made into the pulley. But, that pulley is separately available.
The SC tensioner pulley was not readily available after a search. This pulley is steel and of a clam shell design. It has two halves with the bearing sandwiched between the halves. Machine rivets hold the two halves together and relatively easy to grind off the rivet protrusion (there are five rivets), once grind off drive the rivet out of the mounting hole, and then the two halves can be separated. Tap the bearing out and slide the new bearing in (use the heat/freeze method if need be). I used 5mm diameter x 10mm length class 10.9 allen head screws with nylon lock nuts torque to 120 in-lb to put the two halves back together.
Here is the breakdown of each pulley/bearing/hardware used. Bearings were sourced on eBay, pulleys on RockAuto, and the hardware locally.
MB Part# MSRP Type Replacement AfterMarket Cost
113 202 04 19 655 Double Idler 6203 ZZ C3 $8.40
Dayco 89130 17.92
113 202 00 19 27 Idler Dayco 89161 14.55
112 200 09 70 294 Reg Tension URO 1122000970P 11.64
113 200 01 70 464 SC Tension Bearing 6303 ZZ C3 7.88
Hardware (screws) 5.10
Total Dealer 1,440 DIY 65.49
Formatting of the above chart failed so PDF file attached.
Last edited by machild; Jul 20, 2020 at 03:33 PM. Reason: Formating

E63 Biturbo, UPD Cold Air induction kit, UPD performance crank pulley and UPD adjustable rear suspension with ride height adjustment.
CL55 UPD Cold Air Boost kit, UPD 3000 stall converter, UPD 77mm SC clutched pulley and beltwrap kit, Custom long tubes, UPD crank pulley , UPD suspension kit, UPD SC pulley, Aux. HE, Trunk tank w/rule 2000 pump, Mezeire pump, UPD 5pc idler set, Aluminum rotor hats.
www.ultimatepd.com
instagram @ultimate_pd
facebook.com/ultimatepd
The approach I have assumed is that both tensioners are in good shape and all that is needed is an update to the pulley bearings. You should make sure the tensioner has a consistent tension as you lever it through its arc of range. Any noise, catches, roughness, or change in the smoothness of the arc is reason to replace the entire tensioner.
The engine has two serpentine belts - a regular belt that drives the alternator, A/C compressor, PS pump, and all the other components except the SC. The SC belt only drives the SC. That belt is wider than the typical and the regular serpentine belt.
The current cost of the tensioners and idlers from MB is more than $1,400. If you order them from a MB online dealer you can get that cost down by about 25% or so (down to about $1,100). Aftermarket components are a much lower cost option and if you follow these steps you can keep the cost below $75.
There are two tensioners. The regular belt tension has a plastic pulley so replacing the bearing in that pulley is not an option as the bearing is made into the pulley. But, that pulley is separately available.
The SC tensioner pulley was not readily available after a search. This pulley is steel and of a clam shell design. It has two halves with the bearing sandwiched between the halves. Machine rivets hold the two halves together and relatively easy to grind off the rivet protrusion (there are five rivets), once grind off drive the rivet out of the mounting hole, and then the two halves can be separated. Tap the bearing out and slide the new bearing in (use the heat/freeze method if need be). I used 5mm diameter x 10mm length class 10.9 allen head screws with nylon lock nuts torque to 120 in-lb to put the two halves back together.
Here is the breakdown of each pulley/bearing/hardware used. Bearings were sourced on eBay, pulleys on RockAuto, and the hardware locally.
MB Part# MSRP Type Replacement AfterMarket Cost
113 202 04 19 655 Double Idler 6203 ZZ C3 $8.40
Dayco 89130 17.92
113 202 00 19 27 Idler Dayco 89161 14.55
112 200 09 70 294 Reg Tension URO 1122000970P 11.64
113 200 01 70 464 SC Tension Bearing 6303 ZZ C3 7.88
Hardware (screws) 5.10
Total Dealer 1,440 DIY 65.49
Formatting of the above chart failed so PDF file attached.
Last edited by paste; Mar 27, 2021 at 06:54 AM.




If in doubt, use thread lock but reduce torque a bit to account for the lubricity of the liquid thread lock. FWIW and I am not a professional mechanic; just an amateur wrench turner.
When torquing, you do need a quality wrench, calibrated and no extensions can be used either.
When torquing, you do need a quality wrench, calibrated and no extensions can be used either.

E63 Biturbo, UPD Cold Air induction kit, UPD performance crank pulley and UPD adjustable rear suspension with ride height adjustment.
CL55 UPD Cold Air Boost kit, UPD 3000 stall converter, UPD 77mm SC clutched pulley and beltwrap kit, Custom long tubes, UPD crank pulley , UPD suspension kit, UPD SC pulley, Aux. HE, Trunk tank w/rule 2000 pump, Mezeire pump, UPD 5pc idler set, Aluminum rotor hats.
www.ultimatepd.com
instagram @ultimate_pd
facebook.com/ultimatepd




