OM617A Water Pump Differences
 

I'm getting an om617A engine ready to swap in and as part of the prep I replaced the water pump. The fan pulley won't fit over the shaft of the pump. The interchange book listed 77-85 300Ds and 81-85 300SDs for this pump.

I guess what I'd like to know is if the pulley I have is an oddball, or if the new pump is. The pulley fit the old pump so a pump exists that fits this but I'm not sure where any of it came from on this engine.

-Tad

mb built a lot of very similar pumps with minor details for the application. I would take it back and tell them what I needed and let them sort it out.

All of them are the same. The only difference is the smaller diameter pulley on 84-85 models, which is interchangeable with older models.

Just for clarity's sake; the W115 617 has a different water pump than the 123 617's and the van 616 and 617's have a number of different water pumps that are not compatible with the car versions.

I'll take my pulley with me to the parts store. If it doesn't fit any there I'll start shopping for a standard 617a water pump pulley.

I bought this water pump 6 months ago (it's been a slow spring) so it won't be returned, but for the price I'll spring for one that fits.

-Tad

Would there be a benefit of putting a smaller 84-85 pulley on an 82 to spin the pump faster? It seems like water circulation is just not adequate at low engine speed...

From what I hear, yes. I don't have an 85 sitting around anymore though.

-Tad

Well the ******** water pump for a 1981 300SD has a center shaft that is too big. It is a GATES #41160. The pump I got from Advance Auto for a 1983 300SD does have the correct shaft size though. Go figure.

Thanks for the advice all.

I'll install an aux water pump on a switch for the heater core for now.

-Tad

Yes, but you must use the plastic fan as well. Using the smaller pulley with the aluminum fan can = fan blade failure (very nasty).

The difference is something like 0.9:1 instead of 1.09:1. There is a TSB about it if somebody has access to AllData to get it.