This job is really really easy - takes 20 minutes at max. This is for the 3.2 litre V6 engines made by Mercedes Benz - same applies for the 4.3 litre V8 (M113) - not applicable for older V8s
tools required
E torx bit 10 and 12
ratchet
extension stubby (4 inches)
torque ratchet (very important)
The belt tensioner part on this engine has been superseded and requires change to prevent catastrophe - my old one (OE MB part was wobbly and noisy - I did inject some grease into the bearing but it still was slightly noisy, which I dont approve of on my own car) - The belt on my engine is OE MB - which is a very long lasting and high quality belt.
Steps
unload tension wheel using E10 on snout of tension wheel and lock with allen key or nail etc.
the entire assembly is held by 2 bolts - here is the bottom one
This is the new OEM part, made by Litens, This one has a hexagon cast into the assembly to rotate tensioner into service position unlike the original old part which required turning the stud with the torx bit.
Critical points
1 - The tensioner unit is a very strong part, if your tool slips while unloading it it can cause very bad injury. If the locking pin breaks it will cause very bad injury
2 - The torque of the 2 bolts must not exceed 18 lb/ft while mounting otherwise you run the risk of stripping the threads in the timing case where this unit mounts.
