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Removing/Replacing Waterpump

Started by Boydness, 26 December 2006, 01:04 PM

Boydness


  It sounds like the bearings are going bad on my '78 450SEL water pump.
  I hear a mechanical-type grinding noise and the pulley seems to rotate in an oval rotation.

  What is involved with removing and replacing the waterpump?
  Does anyone have the detailed instructions on the process?
  Are there any surprises (ie other components having to be removed also)?


Steven


michaeld

You can actually find the MBz procedure for removing and installing a water pump on this site by going to http://w116.org/library.php and clicking on "Engine Manual."

As for "surprises," you'll definitely find some.  You will probably have to loosen the power steering pump (as well as the various pulleys) to get it off.  And don't forget to disconnect the 212F switch on top of the pump.   In order to get two of the bolts off, you have to rotate the crankshaft pulley until the notch in the vibration dampener aligns with the bolts.  That's quite a surprise.  And then you will turn the crankshaft until the #1 piston is at TDC and remove the distributor - and be sure to mark the rotor and distributor in relation to one another, and NOT to move the crankshaft after the distributor is removed - to get to ALL the water pump bolts.  Yeah, this water pump is quite a surprise.

As someone who may be facing the same issue, I will send up a prayer for you.

116.025

Wow, Michaeld, that makes it sound a bit more complicated than I remember when dad and I replaced the water pump on mom's 450SEL.  I KNOW we didn't remove the distributor...I mean, the service lit hasn't really steered me wrong yet, though all we had when we did that job was a Haynes manual (which HASN'T always steered me right) and tools.

michaeld

116.025,
It sounds to me like you and your dad had some pretty good times working on cars.  Every man who had a dad like that is far more fortunate than all the rich kids in the world combined in today's self-centered world.

I hope you are right, 116, for both Boydness and possibly my own case.  I was ready with an answer because I'd been reading up on a water pump install.  The Chiltons, Haynes, and MBz manuals all call for the distributor to go.  Maybe it's one of those judgment calls.  For instance, when I replaced my thermostat, I didn't want to loosen the alternator - as the manual called for - and instead worked around the alt and pulley.  Mind you, by the time I was done, I realized that just loosening the alternator probably would have been easier!

P.S.  My dad got into "rock hounding," and he and I used to go into the deserts and hunt rocks.  (Rocks are difficult quarry to hunt, because they are so quiet and stealthy.)  Some of my best childhood memories were with my dad, banging away on some boulder out in the middle of nowhere.  Sounds like you and I were both "rich." 

michaeld

I meant to label my pic, but forgot (and now I'm too lazy to go back and upload the pic again!).

Here is a picture of my water pump with the upper housing removed, and the warmup governor pulled off.

Removing the warming up governor is not in the manual per removal/install of a water pump, but boy it makes it easier to get in there.  I wanted to replace those two bypass hoses that mount between the water pump and the head, and the governor blocked my access to the hose clips.



The warm up governor is at the top of the picture, near the center.  You should recognize it if you pull off your air box.  It mounts to the plate in the middle of the picture, with the bundled ignition wires above it and the blue vacuum line below it.

There are a two vacuum hoses that connect to the governor.  Note their position before taking it off!  And, as you can see, there are two fuel lines that have to come off the top of the governor.  These can be taken off w/ 2 12mm open-end wrenches, and 2 14mm open-end wrenches.  The governor itself is connected to the plate above the water pump by 2 5mm hex nuts.

I called a MBz mechanic at the dealership and verified that no terrible thing would happen if the governor was removed.  I have a rule that goes, "If you don't understand what a thing is or what it does, LITHA."  LITHA stands for "Leave It The Hell Alone."  That's why I called the mechanic: fuel injection and I might be acquaintences, but we sure aint buddies!

I hope this helps your water pump removal project.