Originally Posted by 320wheels

Just thought I'd post the way I changed out my water pump. Not that bad of a DYI job if you take your time.

1. Disconnect the ground cable.
REFIT: Reconnect.
2. Drain the coolant.
Open the expansion tank cap. Place a hose on the drain outlet of the radiator at the bottom left of the unit.(about 3/8” OD vinyl hose will work, might need to cut a small slit to get it to fit the drain outlet). Open the drain plug slowly and gently. Drain the engine block from the bolt which is located on the left bottom side of the engine near the exhaust pipe. This is not absolutely necessary since most of the block will drain when you pull the pump off.....although a bit messy.
[ did not drain until after the pump was removed ... drains more completely and allows back flush of both the block and radiator using hose in the block opening with the drain at the rear open and in the lower radiator hose entry forcing the old coolant out the top.]

REFIT: Use a 50/50 mix of Mercedes Anti-freeze (DO NOT use any other
types...unless you want to do this all again next year) and water. Make sure the drains are closed. Add to the expansion tank. When it shows full, run the engine with the cap off, with the heat on, until the temp raises to the point the thermostat is set for. Put the cap on and continue running a few minutes. You will likely need to add more later.
[I used Prestone's new 'All Makes' antifreeze coolant mix 50/50 and put coolant in block before putting in thermostat and in radiator from top hose entry before putting on that hose but AFTER I put on the lower hose .. needed to add very little and did not have to worry too much about trapped air]


3. Remove Fan Shroud
Unhook the center clasp and turn the narrow circle shroud to unlock, lay it over the fan. Remove clips on the shroud, pull up and then remove the circle. Remove the black plastic cover at the front of the valve housing. (just behind the fan)

REFIT: Lay the circle shroud over the fan. Reattach the shroud and connect the circle to it. Replace the black plastic cover at the front of the valve housing.



4. Remove Fan with Visco Clutch
Make a “pulley securing tool” using a 3/16” x 12+” steel rod with a 45 degree angle, 3/4” from the rod end. Insert the 3/4” bent end behind the fan pulley, into the pre-cast groove, slowly turn the fan by hand until it locks in place. Take a long neck 8mm Allen Key and insert it into the hex bolt on the front of the fan. Put a 3/4” x 18” pipe over the long part of the Allen key for leverage. USE CARE NOT TO DAMAGE THE RADIATOR FINS. Unscrew (normal turn) the hex nut...lean on it if necessary. Make sure the rod keeps the pulley locked. Remove the fan.
[I did not remove the fan .. found I could do the job easily without removing it]
REFIT: Secure the fan well. You may or may not need to use the tool at the pulley while reattaching.

5. Remove radiator hoses and thermostat housing. Remove those which will obviously be in your way. Replace those that are hard or cracked.

REFIT: Replace thermostat. Re-attach all hoses.


5. Remove the Serpentine Belt
Loosen the 10 mm Allen keyed bolt on the tension pulley by 1-2 full turns. This is located to the right of the water pump pulley...about 4 o’clock position. Use a 10mm hex socket for this....also might require some torque to bust loose. Loosen the 13mm adjusting nut 1/2 turn on top of the tension adjuster. Its a long bolt with a hollow interior located just to the right of the thermostat housing. You should now be able to remove the belt. If it shows wear, replace it.

REFIT: Put the belt on the pulleys correctly. Turn the long 13mm tension nut adjuster until there is 3/8 to 1/2” belt deflection between the long run of the pulleys. Do not overtighten. Reset the white pointer on the pulley to the solid line at the left on the indicator. Tighten the 10mm Allen bolt near the water pump pulley.


6. Remove the water pump and power steering pulleys. These are 13mm hex nuts. Use a second wrench to counter the pulley from turning while loosening.

REFIT: Bolt the pulleys back in place.

7. Remove the tension adjuster mechanism. Completely remove the 10mm Allen keyed tension pulley bolt (this is the first one you loosened in Step 5.)
Remove the “Y” bracket in front of the tension pulley. [This is a stamped steel 'frame' that holds the assembly in place .. the tension adjuster subassembly on the back of this assembly is NOT attached and will come off .. note the way it is on so you can replace it correctly]
Unscrew the hex bolt at the top of the little shock absorber on the tension system. Remove the entire unit. If it is tough to get out of the space, hold off until you loosen the power steering pump in the next step.

REFIT: Place the long tension nut through the bracket opening, bolt the shock absorber in place, refit the Y bracket and put the 10mm Allen bolt back in. Make sure the white pointer is in the marked area of the housing...don’t set it at this time.

8. Loosen the Power Steering Pump and move it to the right a little. Unscrew the 4, 13mm hex bolts on the front face of the power steering pump. [DO NOT DO THIS .. the pump is easily removed by removing one bolt at the top back and loosening the one at the lower back .. when replacing them leave them loose until the tensioner assembly is in place and it's bolts are started as there is a bracket on the back of the PS pump assembly whose bolts holes must be aligned with both the bolts (2) at the back of the PS pump and the two bolts on the right side of the Y bracket]

REFIT: Re-secure the PS pump with the proper bolts. ( you may want to first re-install the tensioner device before tightening down the PS...allows a bit more room) [Definitely do install the tensioner to get all bolt holes aligned]

9. Remove the Water Pump. Remove the solid heater pipe from the front of the pump. Leave this solid pipe attached at the other end. [I suggest removing the solid pipe .. this allows much better access to the 6mm hex screw on the upper forward part of the water pump .. with the pipe out of the way I had little trouble getting this screw out with an round head allen wrench, the other three bolts are 13 mm bolts, not allens and a pretty easy to get at with some socket extensions, the solid pipe is secured by a bracket with a 5mm allen in the top center of the block]
Use a 6mm Allen key and Allen socket to get to the 4 [No .. one allen, three hex bolts] bolts holding the pump to the block. They should now be accessible using a ratchet extension and/or the Allen key levered with a small closed end wrench.

REFIT: Clean off the surface of the engine block. Insert O ring into the pump and give the O ring a light layer of grease. Insert the weep drain tube to the bottom of the pump. Mount the pump to the block. Place the small O ring on the heater pipe (might want to also add some grease to it and/or gasket gel). Reconnect it to the pump.