Water pump gasket removal

[Jordan]

So after much struggling I removed my water pump.  It looks like the gasket has literally soldered itself to the housing and is extremely thin.  I almost thought there was no gasket until I felt the outer edge.  It will not come off by rubbing.  I am reluctant to use a screwdriver in that I might scratch the housing which will result in a leak in future.  Can anyone suggest a compound that will not react with the aluminum for removing the gasket material.  Is steel wool OK or maybe nailpolish remover?  Thanks.

[rb6667]

You are wise not to use a screwdriver to remove the remaining gasket.  The face can be easily damaged.  Soak some rags in paint thinner or similar and hold it onto the gasket area for a few minutes.  This should remove the remaining gasket material with a little rubbing.   If not, try and scrape the area with a wooden paint stick after you soak the area again.

Let us know how you do.

RB6667

[mdsalemi]

Note, when I replaced my water pump in 2011 with a Laso, the Laso (a quality aftermarket brand made in Germany) came with a really thin gasket.  I wisely invested in a much thicker OEM gasket, and soaked it in coolant prior to reassembly.

Any number of solvents (carb cleaner, brake cleaner, paint thinner, etc.) with some help from a wooden stick (tongue depressor, popsicle stick, coffee stirrer) should help.

And your assumption and rb's concurrence is right--don't use a screwdriver!

[Jordan]

Thanks, I'll try the paint thinner and a piece of wood (paint stirrer) tomorrow morning. 

One other thing.  The new pump has an indent at one spot where it gets bolted to the main body (same as new gasket).  The old one did not so where do I align the indent?  I assume it is there for a reason.  The old pump had two screws in the housing for positioning (oil I assume) but the new one does not (self lubricating I also assume).  Thanks.

[ja17]

Hello Jordan,

The cut out for the gasket is not critical. It plays a role in a different model application. I assume that the  "weep holes" in the pump were to allow coolant to drain out of the grease packed bearing area of the water pump if  a seal should go bad. In this manner the bearing life of the failing water pump would be extended.  The owner is also warned of the impending failure, as coolant loss can be observed.

Early MB water pumps actually had two plugs in the center housing for 90 w gear oil.  One was to fill, the other was for level (as in the rear diff).  As lubricants improved, this style pump was eliminated for the "maintenance-free" version.

I like to position the "weep holes" downward so dirt and engine fluids  have less of a tenancy to enter the openings.

Many years ago, I was driving a 67 Mercedes 230 sedan from Washington DC to Blacklick Ohio (about 400 miles).  The water pump on the sedan began making noise and vibrating just out of Washington. The bearings were dry and failing. As an emergency measure I removed the fan blade and squirted some 90 W gear oil in the weep holes of the water pump. Removing the blade relieved most of the strain on the failing bearings in the  water pump and the oil eased some of the damage on the bearings. Since the road home was all highway driving, the engine ran nice and cool even without the fan. The rushing air through the radiator at highway speeds kept things cool. I kept a close eye out for any coolant leakage from the pump. The car made it home with no other issues. 

This was an emergency procedure. Do not ever anything to the weep holes in a modern water pump since any added fluids will most likely wash the permanent grease from the bearings!

[Jordan]

OK, two hours after starting I finally got all of the gasket removed.  Used carb cleaner and wood and plastic scraper.  Went to plastic because the wood eventually got soft and stopped working.  I'm sure the pump has never been removed since it rolled off the assembly line.

So now I had a closer look at my replacement pump and while somewhat the same I just want to make sure it is correct.  I have attached two pictures.  As you can see there are two holes on the inside where the fins are located (red circle), none in the original.  Also two holes on the exterior (red circle), also none on the original.  What is the purpose of the holes and is the pump correct?  Lastly, where is the indent situated when installing the pump (big red arrow)?  Before reinstalling everything I want to make sure the pump is correct and aligned correctly.  Thanks for any help.
Marcus

[Jordan]

Thanks Joe.  You must have been typing while I was.  So it sounds like the external holes are weep holes.  What about the internal?  Also forgot to mention that the 5 bolt holes on the new pump are larger than the original, which made me think that maybe the pump was incorrect.

[ja17]

Hello Jordan,

Yes, I see your original pump had the plugs for maintanining oil level.  The new one is maintenance free.  The hole on the internal pump rotor is irrelevant since it turns with the engine. I usually orient the "cut out" in the pump flange the same as it came off.  However it is basically irrelevant since it mainly deals with other model application issues. Just orient one of the weep holes as downward as possible.  The most critical issue on the W113 water pump is its length and the size of center Hub which is used to center up the fan blade. Later W113 cars had a small center hub for the later viscous style fan blade.

Your new water pump is the late "maintenance free" version and looks to have the correct hub and length.

[Jordan]

Thanks again Joe.  Now I can start to put it all back together.