T1N 647 Engine Water Coolant Pump Replacement


Well-known member
Can someone explain why the fan/clutch needs to be stored upright? What happens if it's stored flat?
It has been discussed to death. Go back in this very thread. It has to do with fluid migrating to where it shouldn't.



New member
Thanks Vic. I found the link? It seems that even if you did store it flat for a couple days, the fluid can return back to the reservoir if you store it vertically again. Not sure if there would be any permanent damage. thoughts?
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Well-known member
Thanks Vic. I found the link? It seems that even if you did store it flat for a couple days, the fluid can return back to the reservoir if you store it vertically again. Not sure if there would be any permanent damage. thoughts?

That's not what many service manuals indicate. It may depend upon where the fluid migrates into. In some cases it may be enough to just return to vertical. I have no data.



Well-known member
I'm finally getting around to installing the pump.

There have been comments about Mercedes and remanufactured parts.

It started about a decade ago, but MB USA is selling all bigger parts as remanufactured, when in fact they are new parts.
I observed the same with friends buying alternator for his Dodge.
I found this 30 years ago, with Honda parts. The explanation I got was that taxes for importing "Reman" parts were significantly less, maybe zero. And Honda put a large core charge on the part being replaced, as a way of keeping parts from being rebuilt domestically.
The coolant aka water pump that I got from the dealership appears to be new even though it is labeled remanufactured and has a core charge. The clincher on it being new for me is that the hole for the idler pulley trilobular thread fastener is not threaded. Had the casting been remanufactured that spot would be threaded.

The pump came with the steel main gasket, but no gasket was included for the small outlet. I'll just reuse the removed small gasket with some gasket sealer like I did for the 2004 pump change.


I just ordered an engine coolant aka water pump at higher price than some other options from the local Mercedes dealership. When I picked it up it is a remanufactured unit. The parts person said that remanufactured parts are getting more and more common. It appears that the MB parts supply mode is changing. I assume that the 2 year parts warranty still applies even to reman parts. I didn't think to ask at the time.

View attachment 193992

When I ordered it over the phone they asked for the VIN last 8 digits of my 2006 Freightliner Sprinter. At first the numbers didn't get accepted. I offered to give my 2004 Dodge VIN. "Dodge numbers don't work at all." Eventually the 2006 VIN did work. During the conversation I gave him the full 2006 number string. I don't know if that helped or not.

Anyway. If a NAS aka NAFTA Dodge 2004 - 2006 OM647 owner wants to order a pump or other parts from a Mercedes dealership my 2006 Freightliner 2500 HC 140 Passenger VIN should work.




Well-known member
Got the new coolant pump installed in the 2006.
The 2004 started leaking at 190,000 miles. The 2006 made it to 195,000 miles. (It lasted more years though.)

Some comments from memory.

My old memory and my old eyes failed me when trying to pop the plastic cover off the ribbed idler pulley mounted to the pump. I was trying to pop the inside smaller diameter circle. Fortunately my younger neighbor from across the street stopped by and saw that the outer area of the pulley was what needed to be leveraged to pop the cover. My first dummy move. :bash:

I used a paint dot on the small jumper hose to index the proper orientation. There's a little reference mark on the pump connection. Good move.

I cut out a circle for the pump impeller which allowed me to exactly space my cardboard fastener holder. Overkill, but good for this thread information. It should help those using a torque wrench. (I didn't use one, but I did use the diagram as I tightened the various sized fasteners.) :thumbup:


I used the larger size CR-VE-12 socket on all 9 bolts. I avoided needing to remove the smooth idler pulley when torqueing.

My boring story.
I got everything assembled, coolant refilled, and gave a test start. There was a slight ticking that changed when I moved the still loose cooling stack. ???? Maybe the fan is hitting the plastic shroud? I reassembled everything. At first when started all seemed good. Then a slight ticking noise revealed itself. ??? Did I get a bad pump? I replaced both idlers... maybe those? I crawled under to check the fan clearance. There was no way that the fan was hitting the plastic shroud. A few other checks didn't reveal anything. We had places to go so I quit looking for now.

After pondering it all overnight I went out to the garage, located my mechanics stethoscope and prepared to investigate. When I started the truck there was a god awful clattering and a clang. Needless to say, immediate shutdown was the response from me. I went to check and found an offset box/box wrench on the cement under the truck. ?

When I was tightening the pump Allen bolt I used that box wrench as a torque increaser on the 8 mm Allen key. During the tightening of the fan bolt the tang of the file I was using snapped. Everything kinda fell apart. When that all happened the wrench must have fallen down into the shroud. I didn't notice that. My second dummy move. :bash:

No wonder the ticking changed when I moved the cooling stack. Fortunately when the wrench was ejected there was no collateral damage. That was complete dumb luck. Not to mention that ejecting the wrench saved me a bunch of exploring for the source of the noise. I might still be looking...

Anyway, all is back together and seems just fine.

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Active member
Another way to pull the radiator assembly forward is to use a bar clamp modified to reverse its action from clamping to pulling. (Place 6in angle bar
to protect the radiator's aluminum lip). A sorting box comes handy too.IMG-1045.jpegclamp_reversed.jpeg


2006 T1N 3500 Long & Tall
Had to replace my water pump again at 295K. It was a gates that I had put in at about 160K. So I got about 135K on the gates pump. I put in another gates pump and this time I put in a new Victor Reinz gasket, which is the metal/rubber combination.

Sidenote on metal Gasket:
(Is Mahle k31768 the same as a Victor Reinz gasket?)
~ I just put "MAHLE K31768" Metal gasket part in my Rockauto cart and there was a sidenote that rockauto popped up. It said, "Parts may arrive in Mahle Original or Mahle Victor Reinz Packaging".

Thanks, Chris for the Updates:
~ I'll get a Gates backup pump and metal gasket.
~ My friend also repaired his pump with Gates & a metal gasket from my recommendation that I did because of your posts.

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