M104/95E320 Water Pump Dry Run

[EricSilver]

NOTE: I deleted the thread this was in because of a no longer relevant title and comments. Here is what was saved:

Originally Posted by lee polowczuk

two requests: Don't cheat on the water pump...replacing it is time consuming.

If you do the water pump can you post pics? I have done two 103's, but never a 104...

104's are in my stable and will be engine of choice going forward

I did a dry run of sorts last night under low light and with all hoses, electrical & vacuum connections intact. Access to the four pump bolts was generally direct ,with just some minor angling of the tools required.

My goal was to see if I could 1) insert a 6mm allen key into each bolt and then 2) insert a 6mm allen head socket and the end of a wrench or extension into each bolt. Once inserted I would see if the fit was dry and snug when the tool was rotated. I succeeded with only minor difficulties:

Upper Left Bolt
Readily accessible from above with a Ό drive ratchet and allen head socket. A 3/8 wrench is too big. With the upper radiator and bypass hoses attached I was able to get the 3/8 wrench head and socket in there but had no room to maneuver it onto the bolt. With a Ό drive that would have been easy, even with hoses on. With hoses off (upper radiator, rubber bypass, metal bypass) there will be wide-open access for a Ό tool.
* * There is no need to remove the fan or even the fan shroud. They are not in the way if you come in from above with a slim-head tool. * *

Upper Right Bolt
Option 1: Use 6” or longer wobble extension, or straight extension w/wobble connector, to go in from in front of intake (black plastic piping cover).
Option 2: Use 10” version of above to go in from beneath the intake.

Lower Left Bolt
Sight this bolt above the square reservoir that the pump leaks into when seal fails, then use a 10”- 14” extension for direct access.
* * Straight access with no apparent need for wobble but it might be useful nonetheless. * *

Lower Right Bolt
Sight this bolt by looking down the oil dipstick tube, then feed a long extension (12” or more) from below the intake. Do not confuse it with the other bolt, slightly farther down and to the right, that secures the (tensioner?) mounting bracket.
* * A wobble is essential on this one. Be mindful of the thin vacuum line that will be below your right arm; it snaps easily but can be rejoined with a short length of headlight washer hose. * *

Conclusions:

• Essentially, the pump gets in its own way. Fan, fan shroud, and PS pump did not in any way impede access to the pump bolts and do not appear to be in the way of removal.
  
  
• I was able to make direct contact with each bolt using just the allen key. Thin, maneuverable tools are essential.
  
  
• I will use 1/4" drive tools not only because 3/8" is too big to access the upper left bolt but also because 3/8” extensions are needlessly heavy, which impairs my ability to finesse them into place with just my thumb and two fingers.
  
  
• The bolts are dry and very tight so I will spray them with PBlaster the night before, then clean and dry them with brake cleaner before removal to help prevent any slippage.
  
  
• Since it is proving tough to find a long handled 1/4" ratchet I will get the strongest conventional one I can find and implement my "easy lug bolt removal protocol:”
  Got to Home Depot plumbing dept, get a section of iron pipe (in this case approx 24” to 30”) with an inner diameter that fits snugly over the handle of the wrench. Beginning gently, gradually increase pressure on the pipe/handle to loosen the bolt without breaking the bolt – or breaking a sweat. The long pipe handle allows the use of two hands: One, high up to maximize leverage, to turn the tool and the other, low down, to apply moderate pressure to keep the socket from slipping off the bolt.
  

Finally, in my experience, there is always at least one “gotcha!” with Mercedes repairs. Mine were:

A) The socket of the most accessible bolt – the upper left – either is larger than 6mm or, more likely, rounded and I will need a Bolt-Out standing by for that one.

B) The fact that my 95 E320 thermostat housing is the same as that of a ’96 did not mean the pump is also the same. I will therefore be putting off this repair until next weekend so I can exchange the wrong pump for the correct one.