Very loud "jet engine" noise from engine
 

Hi All,

We brought the e53 in for cooling system refresh and the car came back with a very loud engine noise. It does not sound healthy at all. Mechanic says "he did not cause the sound".

The items that were replaced:
-Waterpump
-Thermostat
-Several hoses


Here's a link to a video of the sound- https://youtu.be/-n0Nc4DQXIE

Any ideas?

not good.............sounds like the timing is way off...........

Sounds like W16 :D
Anyway...do not disturb the car.... noise is ugly! Sounds like there is no exaust pipes! It is hard to say anything just from noise...sounds like may be one candle at least is not working if u know what I mean!
Ask...what they really did there!

Your mechanic sucks, find a new one, fast.

I'm at a loss for words as to how this can happen from a water pump swap!!

I wouldn't drive it. Get it scanned and looked at by a good independent BMW mechanic.

There's an aluminum crossover pipe that connects the exhaust ports on the heads to the secondary (emissions) air pump. If it was left off or loose (or seals are missing) there would be an exhaust leak out the front of the engine. As you should imagine given the story here, that pipe has to be removed to change the parts you have recently changed.

+1^^^ What David.X5 says hits the spot

I was worried about timing guide failure, but what David says above sound much more plausible... and bonus, cheaper.