How does a Water Pump "Go Bad"?

[crazyrog17]

Hey guys, I think I know a lot about cars. I sure can tell you what everything is under the hood and all around the car and most of it how it works (given that it's not all hidden and/or electrical like on most of the new cars!), but I want to understand how a Water Pump "goes bad".

Does it leak? Sieze up? Break into 1.04815x10^3408 pieces?

[GenevaDirt]

Hey guys, I think I know a lot about cars. I sure can tell you what everything is under the hood and all around the car and most of it how it works (given that it's not all hidden and/or electrical like on most of the new cars!), but I want to understand how a Water Pump "goes bad".

Does it leak? Sieze up? Break into 1.04815x10^3408 pieces?

ummm....all of the above. All depends on what the issue is while it is going bad.

[blkfordsedan]

There is a grease packed sealed for life ball bearing in them. The inner race of the bearing is actually a double extended shaft. The impeller presses on one end and the fan belt sheave bolts to the other. When the bearing reaches the end of it's service life it gets sloppy and the radial play takes the seal out with it. It just goes down hill from there.

Some (more expensive) applications actually have a water pump that can be relubed and/or rebuilt. The Mercedes OM352 diesel truck engine in my F250 4X4 is that way. It uses regular open ball bearings pressed on the impeller shaft and a true mechanical type seal (spring & ceramic disc). You fill the pump cavity with grease and can actually re-grease it via a special lube port. Basically, it's built like an actual industrial pump. About 10 years ago the bearings went out in it and destroyed the seal. Not knowing what it was, I priced a complete water pump from the local Freightliner truck dealer. It was $900.....................After talking to one of their mechanics, he told me that I could just buy a $100 seal kit and source the bearings ($30) from a bearing house and rebuild the original one. Should be good for another 300K miles!

[Safety Guy]

I once got a bad water pump from Auto Zone. It had a hairline crack in the body. Fortunately I noticed it before installation on the B6 that went into Luxstiva!

Check your parts carefully!

Karl

[blkfordsedan]

Gotta love the "lifetime warranty" from the McParts stores! You can replace the part as many times as you want, until you get tired of doing it and drop the cash for a quality part! Autozone is usually pretty good, But I stay away from their budget line of parts. They keep switching suppliers looking for the lowest cost. Although, I've never had any hassles returning anything to Autozone. It helps that my neighbor is a Regional Manager for them.

[crazyrog17]

Very informative, blkfordsedan! Thank you. That's cool to learn about the rebuildable pumps and all.

So is there any way to prevent that bearing from falling apart any more than normal wear and tear?