my 300e recently developed a leak in the rear area of the water pump. I am
assuming it is the water pump and have ordered a replacement from an online
vendor. Could someone provide detailed information on replacement
procedure? I have not had much luck finding a good repair manuel to
follow so I would also appreciate suggestions on where to find a good
repair manuel for this vehicle.
Following are the steps I remember doing. I referenced both the Mercedes shop
manual CD & the Haynes 124 manual (Euro version), both of which made it seem
really easy, which it is not, particularly accessing the rear bolts on the
water pump. However, it can be done with patience & the right tools.
Water Pump replacement steps
Make sure you have a replacement pump, replacement seals & relevant tools
Remove the fan shroud
Drain & remove the radiator
Remove the fan (requires special tool to prevent the pulley from turning,
available from Performance Products or other Mercedes tool specialists)
Loosen the belt adjustment main bolt, loosen & remove the belt
Remove the pulleys on the water pump, the fan idler and the power steering
Unbolt the power steering reservoir and push to the right. Leave the hoses
Undo completely the main bolt holding the belt adjustment unit & remove along
with the small shock absorber
Undo & pull out any of the small pipes going to the water pump
You can now access the water pump
You will need 5mm Allen key, plus a 13mm socket, 2 universal joints and 2 to 3
extensions of variable length, all 3/8 inch connection. All of this is
available at your local Sears or equivalent.
Remove the 4 bolts holding the water pump. The rear ones are difficult to get
at & require using the 2 universal joints & the extensions.
Place a large container under the pump area to catch the water
Pull the water pump away from the block to clear the alignment guides & then
forward & out
Use a little high temp silicone in the waterpump main O ring slot to hold the O
ring in place. Wipe off any Silicone on the surface of the water pump. Locate
the 2 rear bolts in their holes in the water pump. Seat the new pump & snug up
the 4 mounting bolts.
Reverse the above procedure to put everything back.
Mercedes have this as a 4 to 5 hour job for an experienced mechanic
Took me 12 hours over 2 days the first time on my 92 300E, & then 8 hours when
I repeated this on a friends 300CE with twin cam head.
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