I purchased a water pump from ******** for my 92 400E. The sealing surfaces for the 2 paper gasket are as cast. One of the as-cast sealing surface is between the block and pump, the other one is between the top block and the pump. Traditionally, all sealing surface is machined to provide a good flat surface with good surface roughness. Has anybody uses their as-cast seal surface pump and has success?

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93 Toyota Corolla 177K
95 S 500 coupe 82K
92 400E 180K (SOLD)
94 E 420 150, blown gaskets (SOLD)
http://www.kanio.net/mercedes_signature.jpg

Is ******** the brand of water pump or did you buy it from ***************?

Sixto
93 300SD

I find this hard to believe as normal. Maybe someone forgot to do the machining process?

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86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

You should call ******** and talk to their parts manager. The company has a great reputaton and I'm sure they will take care of you if there is a problem.

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1986 560 SEL (159K miles)

Shouldn't the pump-to-block o-ring compensate for any surface irregularities?

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

******** might have a great reputation - but which one? There's so many of them.

******** might have a great reputation - but which one?
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I am not going to post the name on this board which is sponsored by MercedesShop.com. Not cool. In my first reply it didn't occur to me that there are probably a dozen ********' around the country.

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1986 560 SEL (159K miles)

It was a GRAF water pump.

I used to work as a design engineer in the auto industry. It has been a tradition that all seal surfaces should be machined. It been that for many years until cost come into the pictures. By using as-cast sealing surface, we saved a lot of cost by not machining the parts. American car makers loves this concept. We have sell compoents that use as-cast sealing surface.

The surface roughness and flatness criteria need to be slack in order for a as-cast seal surfaces. Normally, a machined surface will have a 32Ra and a flatness of the overall surface to be .005" (for a face seal). A as-cast seal surface will be 128Ra, with a .005" or more over certain surface area, not the entire seal surface.

We have success using as cast seal surface. However, I don't know the longevity of the seal and our company never used it on a paper gasket, just o-rings.

Of course the pump of got could be a miss-operation on the machining cell. However, I see it was tapped on the as-cast seal surface, so I doubt it was not mahcined. You always face the surface before you drill and chamfer into it.

__________________
93 Toyota Corolla 177K
95 S 500 coupe 82K
92 400E 180K (SOLD)
94 E 420 150, blown gaskets (SOLD)
http://www.kanio.net/mercedes_signature.jpg