brandwooddixon
Senior Member
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- Jul 31, 2006
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- Your Mercedes
- S63 Coupe 2014
This is a run down on how to replace a coil pack on an M157.
I would imagine that the same process would apply to M278 as the engines are similar in many ways.
OEM coil packs are manufactured by Beru, also sold under the brand name BorgWarner in the US.
Luckily for owners of cars with M157 power plants the engine is fitted with individual coil packs, one per cylinder making them a cheaper and easy DIY fix.
Equipment
E8 socket (internal Torx fitting)
Socket wrench.
Thin/small flat blade screw driver or pick (a cocktail stick could do)
Dielectric grease (non-conducting silicone grease)
Cotton bud / Q-Tip
A code reader to clear stored fault codes.
Method
1. As it was cold and connectors are now old and brittle, I warmed the engine until the oil temperature read about 40 centigrade.
2. Remove small engine panel in front of air filter box. Lift at the front then at the back vertically to release the two clips, one on each side.
3. Remove engine cover. Lift at the front then vertically at the back to release the two clips, one on each side.
4. Loosen the intake pipe to air filter box jubilee clip.
5. Lift the air filter, it clips into place, taking care to release it from the air pipes. Note: that the air filter box has a sensor connector on the back of it. I didn't disconnect it but instead placed the air box to one side, at an angle so as not to strain the cable.
6. Remove the intake pipe that runs from the slam panel to the air filter box. Give it a squeeze near the slam panel as it is held in by two "clips" top and bottom.
7. Underneath where the air filter box was situated you'll find a large soft, moulded insulation layer. This clips into place along the side closest to the side of the car. Removing this should expose the fuel rail, injectors and ignition coils.
In the picture above its the wide, flattish air intake under the pipe that requires squeezing
8. Unclip the coil lead to the coil pack that you wish to remove. You must slide a grey locking tab towards the coil lead, then press it down in order to release an internal catch. Note that as this plastic can get brittle with age I would suggest that you use a small screwdriver or pick to lift the other end of the catch within the top of the connector as you press down and pull the connector.
I've highlighted the tab in the picture below that should be prised up to ensure that the locking tab isn't broken.
9. Undo the two bolts that hold the coil pack in place. Access can be a bit tight. I used a 3/8" socket wrench with my E8 socket. Be careful not to drop anything down the side of the engine bay.
10. Remove the coil pack. The coil pack is removed at an angle towards the side of the engine bay. There is a square sided protrusion on the underside of the spark plug boot that can be used for purchase as it is possible that the boot may separate from the coil pack body.
Here's an image of a new coil pack. Note that it is not shown in the same orientation as when fitted. The square protrusion shown at the top where the boot bends is actually underneath when in situ.
11. It is recommended by MB that you put 1g of dielectric grease around the opening of the coil pack boot before fitting. Put the dielectric grease on the sides of the cotton bud and wipe around the inside of the boot. New Beru coils packs seem to include this already.
12. In the great tradition of a famous series of DIY car mechanic manuals, reassemble in the reverse order. Coil pack bolts are torqued to 9Nm or "just enough" if you don't have a torque wrench that goes that low like me.
Excluding any warm up time the job took be about 20 minutes including picture taking time and gathering tools together.
Note:
If your car was misfiring badly enough to light the EML then the code will be stored permanently and a code reader is likely required to clear it. At least that was the case for my car.
I would imagine that the same process would apply to M278 as the engines are similar in many ways.
OEM coil packs are manufactured by Beru, also sold under the brand name BorgWarner in the US.
Luckily for owners of cars with M157 power plants the engine is fitted with individual coil packs, one per cylinder making them a cheaper and easy DIY fix.
Equipment
E8 socket (internal Torx fitting)
Socket wrench.
Thin/small flat blade screw driver or pick (a cocktail stick could do)
Dielectric grease (non-conducting silicone grease)
Cotton bud / Q-Tip
A code reader to clear stored fault codes.
Method
1. As it was cold and connectors are now old and brittle, I warmed the engine until the oil temperature read about 40 centigrade.
2. Remove small engine panel in front of air filter box. Lift at the front then at the back vertically to release the two clips, one on each side.
3. Remove engine cover. Lift at the front then vertically at the back to release the two clips, one on each side.
4. Loosen the intake pipe to air filter box jubilee clip.
5. Lift the air filter, it clips into place, taking care to release it from the air pipes. Note: that the air filter box has a sensor connector on the back of it. I didn't disconnect it but instead placed the air box to one side, at an angle so as not to strain the cable.
6. Remove the intake pipe that runs from the slam panel to the air filter box. Give it a squeeze near the slam panel as it is held in by two "clips" top and bottom.
7. Underneath where the air filter box was situated you'll find a large soft, moulded insulation layer. This clips into place along the side closest to the side of the car. Removing this should expose the fuel rail, injectors and ignition coils.
In the picture above its the wide, flattish air intake under the pipe that requires squeezing
8. Unclip the coil lead to the coil pack that you wish to remove. You must slide a grey locking tab towards the coil lead, then press it down in order to release an internal catch. Note that as this plastic can get brittle with age I would suggest that you use a small screwdriver or pick to lift the other end of the catch within the top of the connector as you press down and pull the connector.
I've highlighted the tab in the picture below that should be prised up to ensure that the locking tab isn't broken.
9. Undo the two bolts that hold the coil pack in place. Access can be a bit tight. I used a 3/8" socket wrench with my E8 socket. Be careful not to drop anything down the side of the engine bay.
10. Remove the coil pack. The coil pack is removed at an angle towards the side of the engine bay. There is a square sided protrusion on the underside of the spark plug boot that can be used for purchase as it is possible that the boot may separate from the coil pack body.
Here's an image of a new coil pack. Note that it is not shown in the same orientation as when fitted. The square protrusion shown at the top where the boot bends is actually underneath when in situ.
11. It is recommended by MB that you put 1g of dielectric grease around the opening of the coil pack boot before fitting. Put the dielectric grease on the sides of the cotton bud and wipe around the inside of the boot. New Beru coils packs seem to include this already.
12. In the great tradition of a famous series of DIY car mechanic manuals, reassemble in the reverse order. Coil pack bolts are torqued to 9Nm or "just enough" if you don't have a torque wrench that goes that low like me.
Excluding any warm up time the job took be about 20 minutes including picture taking time and gathering tools together.
Note:
If your car was misfiring badly enough to light the EML then the code will be stored permanently and a code reader is likely required to clear it. At least that was the case for my car.
