My wife's 03 C230 4dr has 138k miles so I figured it was time to change the coolant. Right after changing the coolant it started leaking from the pump. Ok fine, time to change the pump. Changed the first one(that was made in China, and didn't want one made there). After changing within 2-3 days it started leaking again. Ok ordered a German made pump this time. Installed it and again with in 4-6 days it was leaking again but smaller amount. I can see dried water/coolant spots on the intake muffler( the jlacklittle shoe box across the front of the engine. Pull the pump again and this time added a small bead of engine silicone around the gasket. Ugh! Still leaking!

We have owned the car from new and it is always garaged, never left California and is very well taken care of.

I've looked at other coolant leak threads but non talk about the trouble I'm having.

Any suggestions would be greatly appreciated!

Thanks

 

Corrosion on the sealing surface where the gasket goes? I've seen it happen on newer cars.

This is one of those things that will be impossible to diag over the internet without seeing it.

 

The surface was totally clean. No oil, dirt or anything. Even when I pulled the first pump off the rubber gasket was in good shape. You can see the water/ coolant spots

 

A few questions. :-)

1) Define "leaking from the pump".
Where exactly?

Fwiw, when water pumps leak, they leak from the seal near the bearing. So, they will drip from the weep hole (if there is one), or from the shaft.


2) How did you torque the bolts?
In what order, and how much?
What do you use for a torque wrench-?