[mr.teejay]

Hey guys. This got me to post. I was did a coolant flush on my 2008 335i 6mt (e90) by pulling out the collant hose connecting to the water pump. Drained it. Connected it back tightened the clamp. I opened the bleeder screw and began filling the expansion tank. Heard a steady drip after pouring a gallon of coolant/water mix.

I see a steady drip from the water pump but can't trace a where exactly where it is coming from when looking from under the car. Looking from up top I can't see anything.

Without the system coolant bleed, how far does the coolant travel/reach? So I know what hoses can be the culprit?? Haven't done the bleed. Dunno if it will help with locating it.

[Blown95ImpalaSS]

something similar happened to me, removed the expansion tank and hoses with finding any leaks or worn components. turns out the water pump was cracked on the black plastic mounting surface causing a slow drip that would empty the expansion tank every 2-3 days. gotta remove the undertray and

[mr.teejay]

Duuuude. So I was looking from under the car and topped off the expansion tank to accelerate the drip (slows down and semi stops after draining about 16 ounces or so rapidly). The water is trickling down the pump and dripping onto the swap bar and the undertray clip. But I can't trace it to any of the visible connections of the thermostats or the water pump (the u-pipe, feed from expansion tank).
I'm reading more about cracks in the pump.

Was the crack visible for you from under the car? Or was it hidden until you removed the pump and inspected it?

I'm leaning towards that. But prolly have to pull it out anyway because I can't trace it from top nor bottom of the car.

[Blown95ImpalaSS]

nope, crack was not visible until the WP was completely off the car