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Replacing Your Vibration Damper on your Mercedes-Benz
 
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Pelican Technical Article:

Replacing Your Vibration Damper on your Mercedes-Benz

Steve Vernon

Time:

5 hour5 hr

Tab:

$0 to $27

Talent:

**

Tools:

6mm, 8mm Allen, 13mm, 19mm wrench

Applicable Models:

Mercedes-Benz W126 (1981-91)

Parts Required:

New Vibration Dampener

Hot Tip:

Be careful working around your radiator

Performance Gain:

Properly balanced engine

Complementary Modification:

Replace belts

The Mercedes-Benz W126 has the proud distinction of having 5 different drive belts. To remove the vibration dampener you must remove all of them as well as the radiator, shroud and fan. If you have an impact gun removing the main blot that holds the dampener to the crank is easy, if you don't it can be quite difficult as it is held there with 300-400 NM of force. I recommend you borrow or rent an impact gun as you run the risk of damaging the cast iron V-belt pulley without one.

You are going to begin by removing the radiator. There are a few things that need to be loosened or removed from under the car, if you are comfortable and small enough to fit under the front of your car you do not need to lift it. If you like or need more you to work, safely lift and support the car.

Make sure the car is cool before you begin working on it. To drain the coolant, locate the plastic drain plug on the bottom of the lower front passenger side of the radiator. Place your drain bucket under the hole and turn the plug with a large screwdriver. Coolant will begin to come out but will not drain rapidly because of the vacuum caused by the sealed system. To get all the fluid out, go up to the coolant reservoir and undo the cap, this will break the vacuum and allow the coolant to flow freely.

Move to the radiator and undo and separate the overflow hose and upper hose from the radiator.

It can be a tight fit to remove the radiator and shroud so give yourself some more room by simply lifting the charcoal canister on the left side of the radiator mount up and out of the way.

Undo the clips holding the shroud to the radiator and radiator to the frame.

Move under the car and disconnect the transmission oil coolant lines from the lower part of the radiator. There will be some fluid that will spill so be prepared for it.

Lift the shroud from its locating taps on the bottom of the radiator and move the shroud back over the fan.

Undo and remove the two lower water hoses from the radiator. You will need to wiggle the shroud around so the outlet pipes clear the shroud when removing it.

The radiator is now free and can be lifted from the car. The radiator has two rubber mounts that sit on grommets in the lower cross frame. Sometimes you need to wiggle the radiator around to free it from the lower mounts, just take care that you do not damage it against the fan or condenser.

Next you need to remove the fan. There are four 10mm bolts holding the back of the Viscofan to the front of the cooling pump. You do not need to remove any of the drive belts to replace the fan. You need to hold the fan in place while unscrewing the four 10mm bolts, and while there are lots of different tools made to do this I just place a large screw driver between the fan center and one of the bolts. They are not held on under a lot of torque and should easily come off. Do NOT attempt to place anything between the fan blades to keep it from turning as you can easily damage the fan and yourself.

Moving on to the belts, begin by removing the air pump belt. The air pump is located on the lower passenger side of the engine.

To remove the belt you will need to loosen the pump itself. Use a 6mm Allen and loosen the Allen bolt at the top of the pump. The pump has a tensioner/locking bolt on its lower housing. There are two nuts on the same bolt. Loosen the outer 13mm nut and then turn the inner 19mm nut. The 19mm has a spiral toothed ring on it that is used to tension the belt. Turn it counter clock wise to loosen the belt and when reinstalling turn it clock wise to tension the belt and while holding the tension tighten down the 13mm bolt.

Don't forget to retighten the 6mm Allen bolt when you are done.

Next remove your A/C belt. To remove the belt you will need to loosen the tensioner on the belt using an 8mm Allen. With the tension off you can now remove the belt.

After those belts are removed you need to loosen the power steering pump to loosen the belt. There are three 13mm nuts holding it on. Loosen the two 13mm nuts attaching the pump to the front plate. With these loosened but not removed, loosen the 13mm nut on the lower driver side of the pump and then use a 13mm wrench from the back of that bolt to turn the toothed bolt in its gear. It is the same system as the other pumps. Turn the rear bolt counter clockwise to loosen the pump, this will allow you to slip the belt off.

Remove the 27mm bolt holding the dampener to the crankshaft. It really is best to rent or borrow an impact gun to do this. With the bolt removed you will want to mark the pulley. The dampener sits on the crank shaft with the help of a Woodruff key and marking everything will help when putting it back together. Then remove the five 13mm bolts holding the pulley to the dampener.

Locate the plastic drain plug on the bottom of the lower front passenger side of the radiator (yellow arrow).
Figure 1

Locate the plastic drain plug on the bottom of the lower front passenger side of the radiator (yellow arrow). Place your drain bucket under the hole and turn the knob.

Remove the cap on the coolant reservoir (red arrow), this will break the vacuum and allow the coolant to flow freely.
Figure 2

Remove the cap on the coolant reservoir (red arrow), this will break the vacuum and allow the coolant to flow freely.

The coolant should now flow freely (red arrow).
Figure 3

The coolant should now flow freely (red arrow).

Undo and separate the overflow hose (red arrow) and upper hose (green arrow) from the radiator.
Figure 4

Undo and separate the overflow hose (red arrow) and upper hose (green arrow) from the radiator.

Give yourself more room by simply lifting the charcoal canister on the left side of the radiator mount up and out of the way (red arrow).
Figure 5

Give yourself more room by simply lifting the charcoal canister on the left side of the radiator mount up and out of the way (red arrow).

Undo the clips holding the shroud to the radiator (green arrows) and radiator to the frame (red arrows).
Figure 6

Undo the clips holding the shroud to the radiator (green arrows) and radiator to the frame (red arrows).

Disconnect the transmission oil coolant lines (red arrows) from the lower part of the radiator.
Figure 7

Disconnect the transmission oil coolant lines (red arrows) from the lower part of the radiator. There will be some fluid that will spill so be prepared for it. Lift the shroud from its locating taps (green arrows) on the bottom of the radiator and move the shroud back over the fan.

Undo and remove the two lower hoses from the radiator (red arrows).
Figure 8

Undo and remove the two lower hoses from the radiator (red arrows). You will need to wiggle the shroud around so the outlet pipes clear the shroud when removing it.

The radiator is now free and can be lifted from the car.
Figure 9

The radiator is now free and can be lifted from the car. The radiator has two rubber mounts that sit on grommets in the lower cross frame. Sometimes you need to wiggle the radiator around to free it from the lower mounts, just take care that you do not damage it against the fan or condenser.

With the radiator gone the shroud can easily be removed from the engine bay.
Figure 10

With the radiator gone the shroud can easily be removed from the engine bay.

There are four 10mm bolts holding the back of the Viscofan to the front of the cooling pump (green arrow).
Figure 11

There are four 10mm bolts holding the back of the Viscofan to the front of the cooling pump (green arrow). You need to hold the fan in place while unscrewing the four 10mm bolts, and while there are lots of different tools made to do this I just place a large screw driver between the fan center shaft and one of the bolts. The bolts are not held on under a lot of torque and should easily come off. Do NOT attempt to place anything between the fan blades to keep it from turning as you can easily damage the fan and yourself.

This photo illustrates the five different belts on the W126 (there are two belts on the water pump, power steering pump, yellow arrow).
Figure 12

This photo illustrates the five different belts on the W126 (there are two belts on the water pump, power steering pump, yellow arrow). The green arrow shows the air pump belt, the red arrow shows the alternator belt and the blue arrow shows the A/C belt. Note: most of the front of the car has been removed for demonstration purposes.

This is what the air pump looks like from under the car.
Figure 13

This is what the air pump looks like from under the car. Loosen the 6mm Allen (green arrow) and then loosen the 13mm bolt (red arrow). With the bolt loosened you can turn the 19mm bolt (yellow arrow) and either un-tension or re-tension the belt.

Here you can see how the 19mm bolt has teeth in it (red arrow) and the toothed gate (green arrow) that the bolt turns in.
Figure 14

Here you can see how the 19mm bolt has teeth in it (red arrow) and the toothed gate (green arrow) that the bolt turns in.

With the air pump belt removed you can use an 8mm Allen to loosen the tensioner (yellow arrow) and then remove the A/C belt.
Figure 15

With the air pump belt removed you can use an 8mm Allen to loosen the tensioner (yellow arrow) and then remove the A/C belt.

Loosen the 17mm bolt (red arrow) attaching the alternator to the solid mount.
Figure 16

Loosen the 17mm bolt (red arrow) attaching the alternator to the solid mount. There is a nut and bolt that attaches the alternator to the arm bracket. This bolt has the tensioner teeth built into it like the other accessories (green arrow).

You need to use a 17mm socket and loosen the nut on the back of the alternator (red arrow).
Figure 17

You need to use a 17mm socket and loosen the nut on the back of the alternator (red arrow).

With this loose you can use your 17mm wrench on the front bolt to take the tension off the belt.
Figure 18

With this loose you can use your 17mm wrench on the front bolt to take the tension off the belt.

This photo shows the route of the two power steering pump and cooling pump belts (red arrows), the location of the power steering pump pulley (green arrow) and the three 13mm nuts and bolts connecting it to the car (yellow arrows, one is hidden).
Figure 19

This photo shows the route of the two power steering pump and cooling pump belts (red arrows), the location of the power steering pump pulley (green arrow) and the three 13mm nuts and bolts connecting it to the car (yellow arrows, one is hidden).

Loosen the two 13mm nuts (red arrows) attaching the pump to the front plate.
Figure 20

Loosen the two 13mm nuts (red arrows) attaching the pump to the front plate.

On the lower driver side of the pump use a 13mm wrench to loosen the front bolt (red arrow), and then working from the back turn the toothed bolt in its gear (yellow arrow).
Figure 21

On the lower driver side of the pump use a 13mm wrench to loosen the front bolt (red arrow), and then working from the back turn the toothed bolt in its gear (yellow arrow). It is the same system as the other pumps. Turn the rear bolt counter clockwise to loosen the pump.

Remove the 27mm bolt (green arrow) holding the dampener to the crankshaft.
Figure 22

Remove the 27mm bolt (green arrow) holding the dampener to the crankshaft. It really is best to rent or borrow an impact gun to do this. Then remove the five 13mm bolts (red arrow) holding the pulley to the dampener.

With the bolt removed you will want to mark the pulley.
Figure 23

With the bolt removed you will want to mark the pulley. The dampener sits on the crank shaft with the help of a Woodruff key and marking everything will help when putting it back together.

The red arrow show the groove on the dampener that the Woodruff key on the crankshaft sits in.
Figure 24

The red arrow show the groove on the dampener that the Woodruff key on the crankshaft sits in.

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Comments and Suggestions:
84benz Comments: How do you replace the key if it is damaged ?
February 10, 2016
  Followup from the Pelican Staff: Key in the crankshaft? Some can be removed, some require the crankshaft to be replaced. Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
gmkjr Comments: You can remove the vibration dampener by removing the six 13 mm bolts surrounding the center bolt. Be certain to mark it carefully so it can be re-installed in the same orientation it will only go one way. You need to R/R the VD in order to change the water pump.

If you must remove the hub from the crankshaft, you sould probably soak everything with penetrating fluid before trying to remove the hub. Obviously, you want to loosen the bolt and leave it in place until the hub starts to move. You should also replace the hub seal when you are putting things back together.
May 14, 2015
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
Rich Comments: If anybody else comes across this, and needs to get the hub off and not just the pulley, the only way to get mine off was a two arm puller. Just be very careful you don't damage your crankshaft. Even with a high quality 2 arm puller, mine was hard to get off, so there was no way anything else would have done it corrosion was the cause of the difficulty
January 4, 2014
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
Rich Comments: How do you make Figure 24 happen? I am doing another job that requires me to remove the crank hub, and I cannot get it off to save my life.
January 1, 2014
  Followup from the Pelican Staff: If removing only the pulley, remove the 13mm bolts, not the large center bolt Then tap pulley with a soft-faced hammer to free it. - Nick at Pelican Parts  

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