Remove/Install Chain Tensioner - AR05.10-P-7800MRD

Engine 274.9 in model 213 

Engine 274.9 in model 238 

Shown on engine 274.9 in model 213 

(except 213.048/049/148) 

Fig 1: Timing Chain Tensioner Components Location - Engine 274.9 In Model 213 (Shown Except Models 213.048/049/148)

Courtesy of MERCEDES-BENZ USA

	Risk of injury  to skin and eyes due to handling of engine oil. Risk of poisoning  caused by swallowing engine oil	Wear protective gloves, protective clothing and safety glasses. Do not fill engine oil into beverage containers.	AS18.00-Z-0001-01A
	Risk of injury  . Skin or eye injuries may result when handling hot or glowing objects.	Wear protective gloves, protective clothing and safety glasses, if necessary.	AS00.00-Z-0002-01A
	Notes on avoiding damage through contamination and foreign objects		AH00.00-P-5000-01A
	Remove/install
1	Remove upper engine cover	Only install top engine cover after the leak test.
2	Remove electric coolant pump	Engine 274.9 in model 213 (except 213.048/049/148) Engine 274.9 in model 238 (except 238.348/448)	AR20.10-P-1281MRD
3	Remove cap of chain tensioner (1)	: Penetrate the cap of chain tensioner (1) using a screwdriver and pry out. Otherwise the timing case cover will be damaged and leaks occur. Replace cap of chain tensioner (1).
4	Remove chain tensioner (1)	Screw/bolt, chain tensioner to bracket	*BA05.10-P-1001-01F
	Check
5	Check chain tensioner (1)	The chain tensioner (1) may only now be reused if it did not have any noticeable problems during previous operation and all components of the chain drive do not show any signs of damage or no components of the chain drive were replaced. Engine damage can occur otherwise. The chain tensioner (1) is pretensioned by an internal spring and moves out autonomously when being removed. If the chain tensioner (1) does not move out on its own. ↓ Replace chain tensioner (1).
6	Check the bracket of chain tensioner (1) for damage	For damage ↓ Remove timing case cover and replace bracket of chain tensioner (1).	AR01.40-P-8000MRD
		Screw/bolt, chain tensioner holder to crankcase	*BA05.10-P-1003-01F
7	Install in the reverse order
	Risk of accident  from vehicle starting off by itself when engine running. Risk of injury  (bruises and burns) resulting from working on the engine while it is being started or when it is running.	Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
8	Carry out an engine test run, checking the engine for proper operation and leaktightness
9	Install upper engine cover