umblecumbuz
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- Your Mercedes
- S204 and CLC 204 cdi, MX5, Kia Soul
CHANGING THE PILOT BUSH ON A 722.6 5-SPEED GEARBOX
The pilot bush on my C270 5-speed box began to weep. This is a known weakness, and is simple to remedy. Total time taken, including tea break and road-testing was less than an hour. This is how I did it:
Raise the vehicle so that you can work underneath. Car ramps are sufficient. It goes without saying that cleanliness is vital throughout this job. The only tools required are a 7mm and an 8mm socket with ratchet and extension. A small quantity of ATF will also be needed for topping up, along with a container to catch around half a litre of fluid or less that will drain from the gearbox.
Remove the two plastic undertrays, one beneath the engine and the other beneath the gearbox. You will need the 8mm socket and ratchet for this.
At the front left corner of the gearbox, viewing from the front of the car, you will see the pilot bush housing (photo). Clean the area thoroughly. The electronic connection just swivels anti-clockwise and pulls out of this housing (photo). Pull this out and swing it out of the way.
In the recessed centre of the pilot bush housing there can now be seen a setscrew. Undo this, using the 7mm socket with a short extension. It is a captive setscrew, so will remain in the plastic fixture. Once it is undone, the bush itself, with a bit of jiggling side to side, can now be removed (photo). There will be some leakage of ATF at this point, about a third of a litre. Let it drain into the container, then thoroughly clean around the area.
Examine the new bush. If it is the latest revision, it will have two black O-rings fitted (photo). Before fitting, swing the cream-coloured nylon outer piece anti-clockwise until it comes to a definite stop. This nylon piece has a thumb tag to help you do this, and to help locate and tighten the electrical connection into place later. Wipe the new bush O-rings with ATF, and carefully insert in the gearbox housing. This requires some care, as it will only seat properly in one position. Gently twist to and fro as you insert it, and you will feel when it engages correctly. Push hard when you feel it engage correctly, as you need to overcome the compression-resistance of the two O-rings. It will slot firmly into place. Tighten the 7mm central setscrew to pull it completely home.
WARNING: O-rings do not need excessive tightening to make a seal, as they seal fully by contact with two mating surfaces. Do not overtighten this setscrew, or it will break off in the gearbox and you will have a very expensive repair! Just nip it up sufficiently to hold the pilot bush firmly.
Now you are in a position to refit the electrical connector. This also can only go back in one position, and you can do this easily by feel. Once located, swivel the nylon thumb tag clockwise to its fullest extent. It will lock home when this is done correctly.
That’s the job almost done. It goes without saying that you must observe utmost cleanliness throughout. Refill the gearbox through the ‘dipstick’ tube with the same amount of ATF that was lost during the job. Roadtest and recheck that the new pilot bush is properly sealed before you replace the two plastic covers under the gearbox and engine.
Time taken: Removing and refitting the plastic covers took me less than ten minutes. Removing and renewing the pilot bush as described here took me 23 minutes. Topping up the gearbox oil took a further five minutes (slow process). Total time, less than an hour including tea break and road-testing.
The Part Number for this bush is A 203 540 02 03, and the cost from an MB Dealer is £26.
The pilot bush on my C270 5-speed box began to weep. This is a known weakness, and is simple to remedy. Total time taken, including tea break and road-testing was less than an hour. This is how I did it:
Raise the vehicle so that you can work underneath. Car ramps are sufficient. It goes without saying that cleanliness is vital throughout this job. The only tools required are a 7mm and an 8mm socket with ratchet and extension. A small quantity of ATF will also be needed for topping up, along with a container to catch around half a litre of fluid or less that will drain from the gearbox.
Remove the two plastic undertrays, one beneath the engine and the other beneath the gearbox. You will need the 8mm socket and ratchet for this.
At the front left corner of the gearbox, viewing from the front of the car, you will see the pilot bush housing (photo). Clean the area thoroughly. The electronic connection just swivels anti-clockwise and pulls out of this housing (photo). Pull this out and swing it out of the way.
In the recessed centre of the pilot bush housing there can now be seen a setscrew. Undo this, using the 7mm socket with a short extension. It is a captive setscrew, so will remain in the plastic fixture. Once it is undone, the bush itself, with a bit of jiggling side to side, can now be removed (photo). There will be some leakage of ATF at this point, about a third of a litre. Let it drain into the container, then thoroughly clean around the area.
Examine the new bush. If it is the latest revision, it will have two black O-rings fitted (photo). Before fitting, swing the cream-coloured nylon outer piece anti-clockwise until it comes to a definite stop. This nylon piece has a thumb tag to help you do this, and to help locate and tighten the electrical connection into place later. Wipe the new bush O-rings with ATF, and carefully insert in the gearbox housing. This requires some care, as it will only seat properly in one position. Gently twist to and fro as you insert it, and you will feel when it engages correctly. Push hard when you feel it engage correctly, as you need to overcome the compression-resistance of the two O-rings. It will slot firmly into place. Tighten the 7mm central setscrew to pull it completely home.
WARNING: O-rings do not need excessive tightening to make a seal, as they seal fully by contact with two mating surfaces. Do not overtighten this setscrew, or it will break off in the gearbox and you will have a very expensive repair! Just nip it up sufficiently to hold the pilot bush firmly.
Now you are in a position to refit the electrical connector. This also can only go back in one position, and you can do this easily by feel. Once located, swivel the nylon thumb tag clockwise to its fullest extent. It will lock home when this is done correctly.
That’s the job almost done. It goes without saying that you must observe utmost cleanliness throughout. Refill the gearbox through the ‘dipstick’ tube with the same amount of ATF that was lost during the job. Roadtest and recheck that the new pilot bush is properly sealed before you replace the two plastic covers under the gearbox and engine.
Time taken: Removing and refitting the plastic covers took me less than ten minutes. Removing and renewing the pilot bush as described here took me 23 minutes. Topping up the gearbox oil took a further five minutes (slow process). Total time, less than an hour including tea break and road-testing.
The Part Number for this bush is A 203 540 02 03, and the cost from an MB Dealer is £26.
