Mercedes-Benz – How to remove / install the chain tensioner | Engine M276, M278

Mercedes-Benz – How to remove / install the chain tensioner | Engine M276, M278

If the engine rattles, this may be due to a defective chain tensioner.
To remove the engine, remove the engine cover.
Take out the air filter housing.
Always replace the clamp later.
Disconnect the purge line from the resonance intake manifold.
The engine has been removed here for better viewing.
Disconnect the vent line from the resonance intake manifold.
Disconnect the connector from the pressure sensor downstream of throttle valve.
Also disconnect connector on throttle valve actuator.
Unclip electrical line from throttle valve actuator.
The retaining clip is seated below it.
Disconnect vacuum line from brake booster.
Unclip vacuum hose from resonance intake manifold.
Detach vacuum hose from vacuum line.
Disconnect electrical connector from “Intake manifold intake air temperature sensor”.
Detach vacuum line of vacuum pump.
Disconnect connectors of selector drum on resonance flap on intake manifold.
Remove cover from resonance intake manifold.
Remove all screws and remove resonance intake manifold.
Take out crankcase ventilation to gain access to right chain tensioner.
Disconnect connectors from solenoids of camshaft.
Unclip electrical line for engine wiring harness at front cover.
Disconnect connector on right Hall sensor and disconnect ground line.
Place wiring harness to one side.
Remove screws on front cover.
These aluminium screws may not be reused.
Loosen cover at prying lugs with wedge and detach towards front.
At center bolt of crankshaft, crank engine in normal rotation direction to 40° crank angle after TDC of 1st cylinder.
The two marker edges must point downwards and inwards.
If you cannot see them, rotate crankshaft through another 360° until the markings are at the right position.
Remove screws and remove chain tensioner.
Check chain tensioner and its extension.
It may only be reused if the extension is 74.5 mm and it is undamaged.
Retension chain tensioner.
Use a vise with plastic jaws to do so.
Reinstall chain tensioner.
Only use cleaning spray for the subsequent cleaning.
Clean sealing surface on cylinder head, cylinder head cover and front cover.
Never use sharp-edged tools or abrasive paper to remove protruding sealant residue.
To avoid engine damage: make sure nothing falls in the engine.
Apply sealant with a width of 1 mm.
Carefully reattach cover with sealant.
Only use new screws. Tighten them to 5 Nm.
Install in the reverse order.
Note: Replace all seals.

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More Information:
Cleaning spray A001 986 71 71 10
Sealant A003 989 98 20

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Comments

Mick Hampton says:

If you have to be 40 degrees past TDC for the passenger side. Where do you have to be for the driver side?

BMW 335I says:

Smart to put a drop of oil on the new tensioner. On the rubbber end before first start.

Ernar Kelimbetov says:

этот мужик вроде кабана ремонтировал в 90е)

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