In the past couple of weeks I've been hearing this low groaning sound coming from the engine. I've had this 04' Disco for about 5 years so I'm pretty familiar with them and this forum. At first I thought it was maybe the waterfall sound that I've read about on many forums but it's not that sound after watching some videos. Then I thought about the water pump but this sound only happens when the engine is cold but once it gets to op temperature it goes away so i counted out the water pump as that would make noise all the time and probably be a different sound (I'm assuming bearings going out.)

I know this is kind of vague but not sure how else to explain it.

 

Is yoir truck equipped with SAI? It could be the SAI pump on passenger side of engine.

 

I don't believe I have the secondary air. It's an S with the Trail Package.

 

Well the low growl turned into a grinding noise then coolant flowing out of the bottom so I'm assuming it's the water pump. It's got 140K on it so probably time to replace.