Water pump replacement m104
 

just changed out the water pump in my e320. added water to the radiator....started it up.... water pump pullley wasn't turning..

shut engine off...loosened the belt...

When i turn the pully it turns about 180 degrees and hits a spot where it won't turn, unless i really try..

in other words, it won't turn freely 360 degrees or a full circle.

What did I do wrong... I have done several of these and this one is killing me....

Did u spin the impeller on the new pump before u installed it. Did it turn freely. If so I'm not aware of anything that would interfere with the impeller. Pull t-stat housing and bottom pump hose and inspect. We actually just finished installing a new Graf on one of our m104 engines a couple of hours ago. All went well.

Make sure one of the pulley bolts isn't too long ( as in got mixed up with a pump mounting bolt. )

Other than that, there really isn't anything that could have been put together wrong as the pump comes as a complete unit. ( Unless something got dropped into the pump )

i am going to recheck.... all i can think is that i didn't see if it free turned from the start... the pulley bolts are the short ones...... so that's not an issue...

Lee, what brand water pump did you install? I buy reconditioned water pumps from our local MB dealer. MBUSA provides a 1-year warranty on all reconditioned parts, labor is not covered.

my fault.... even though the pulley's look identical...the one from the water pump and the one from the power steering pump had to be switched..... it looks like they have weights attached (for balance?) anyway switching them cleared up the problem

Early M104's had a pulley with a 126 part number but later ones were the same as the power steering pump pulley.
What brand of pump did you use? Perhaps the casting is slightly different from the original.

Lee, the power steering pump and water pump on our two 1995 E320's have identical pulleys and attachment bolts. It's odd that MB would utilize different pulleys on older models of the same vehicle. The MB designers tend to be consistent with similar items on any given vehicle.

The 3 bolt pulleys are the same, I suspect that the casting was a bit bigger in one spot ( or an aftermarket casting that made it's way in to the rebuild pool ) and the balance weight just happened to be in the wrong / right place.

Went to install Laso..and that's the one I had an original problem with.. went with Graf... Laso was no longer available from the supplier... hmm..

Maybe I should clarify..

The balance weight was getting hung up on tensioner bracker...

Both pulleys were identical except for one thing: The one on the power steering pump had two "weights" attached or welded.... the one for the water pump had one.

My biggest issue..is that I did this over two weekends, because of frigid temps and feeling sick.... and I guess I transposed the pulleys...

I still vote that the pulleys are the same part number and that during balancing, weights got stacked up. There isn't any physical reason to have different balance between the WP and PS pump. Had this pulley swap have occurred at the factory, the double weight pulley would have been discarded.

Balanced pulleys are another reason MB cost more $ and run so smooth. Many cars only balance large diameter / wide or double stack pulleys.