How to change water pump in Mercedes E320? How do you remove the the mounting bolts underneith the water pump?

carefully pri or tap tensioner assembly ,make sure all bolts are removed

REPLACE WATER ALL YOU NEED TO DO IS DRAIN THE COOLANT SYSTEM.REMOVE THE ENGINE COOLING FAN AND CLUTCH THEN THE FAN SHROUD.REMOVE ENGINE COVER IF EQUIPPED.THEN REMOVE THE ACCESSORY DRIVE BELT.UNBOLT THE POWER STEERING PUMP MOVE IT ASIDE DONT DISCONNECT ANY POWER STEERING PUMP HOSES.DISCONNECT WATER PUMP HOSES, REMOVE BELT PULLEY THEN REMOVE WATER PUMP MOUNTING BOLTS AND WATER PUMP.CLEAN WATER PUMP MATING SURFACE BE CAREFUL DONT SCRATCH PUMP SURFACE. BESURE WHEN YOU INSTALL NEW WATER PUMP USE GASKET SEALANT ON BOTH SIDE OF GASKET TO KEEP IT FROM LEAKING COOLANT.

You have to carefully remove the inner door trim, disconnect the airbags and then remove the weather stripping. There are some obvious nuts/bolts & clips that you will see.

what would then approx labor cost be on installing a water pump on Mercedes e320

No I don't have a diagram I am soory,but you have to hold the engine from underneith and then remove the motor mount on the passenger side to be able to get the pump out.You will have to jack the motor in order to get the long bolts out of the waterpump and motor to engine mount bolts.

Remove the electric fan. Remonve the drive belt. Lower the AC compressor by removing the three bolts. Do not disconnect the gas lines. Raise vehicle and remove the engine panel. remove upper engine mount bolts. Raise engine and remove lower engine mount bolts. Then remove engine mount.
These instructions are for removing the engine mount on the left side. I haven't done the right side .

Wanted to do the job myself, but I will have it done at the carservice.

It is not complicated, depending on what hands-on level of DIY on car. Here are what need to do, so you can estimate how easy or hard when you look through your engine. Drain all the coolant, remove the thermostat housing, remove the fan, belt. Remove the water pump pulley. There are 4 bolts to hold the water pump in place.If you think you can take them out and put them in without removing the AC compressor then you can do it. I did it twice without removing the AC. The pump was fine for the second time, but for leaking seal. At dealer, it is easier to access from the bottom since they have a lifter. But it is doable at home. Have fun if you decide to do it.

Drain the coolant
Remove air cleaner assembly
Disconnect water hoses from radiator
Remove drive belt
Remove power steering pump
Remove water pump drive pulley
Loosten hose clamps on cylinder head tp water pump cooling line
Remove water pump mounting bolts and water pump

Just reverse these procedures to install new pump.