Rattling engine noise

Yeah I'm pretty sure it's the water pump. I'm going to order a new one tonight w/ a thermostat. Everything else on the cooling system is recent or has been done within the last 2 years according to the records so I'll replace those when the time comes.

BTW, good looking coupe.

Did u run the car without the belts? I found that the water pump cover is a little flimsy and that the noise disappeared when the water pump wasnt running

I didn't get a chance to get the fan off yesterday. I took the car by a mechanic today and he said that it's most likely the water pump. He also noticed how wobbly the fan is as well so that makes sense. I already ordered the water pump and a gallon of coolant and it should be here by the end of the week. I was going to replace the thermostat but it will have to wait.

Originally Posted by ryannel2003

I didn't get a chance to get the fan off yesterday. I took the car by a mechanic today and he said that it's most likely the water pump. He also noticed how wobbly the fan is as well so that makes sense. I already ordered the water pump and a gallon of coolant and it should be here by the end of the week. I was going to replace the thermostat but it will have to wait.

You may want to add a second gallon of coolant to that order, if you can. You lose a good bit during the bleeding process, if it decides to be difficult. It is better to have too much, than not enough.

Didn't think of that. Luckily a buddy of mine has another gallon of BMW coolant we can use if it proves to be difficult.

It was the water pump guys. Very loose when we took the pulley off and the new one installed with no issues and the car is quiet as a mouse. Thanks for all the help!

I now have the same noise. I was replacing the OFHG and the vanos oil line last weekend, and I guess I was tired because I made two stupid mistakes. First, I mis-routed the inner belt over the top pulley (roller?) instead of under it, then I didn't clip the upper radiator hose back to the water pump tightly enough. So on my way to work, suddenly the heat went cold and I had steam/smoke everywhere, as the host popped loose and sprayed coolant all over the engine compartment. I snapped the hose on correctly and added coolant (didn't bleed the system), but then was running way hot on the way home (I had to coast with the motor shut down a good portion of the way home to keep it out of the red.

Anyway, that's when I realized I had the belt on incorrectly, so I popped the cap back off the tensioner and loosened the belt enough to rout it properly.

I'm still showing a low coolant light (have not added any again since running hot yesterday - and have not driven it), but I have this crazy rattle that sounds like it is coming from the belts.

Oh - and I still have no heat and I've come to see that the electric fan is not working either.

So my question is - could the above scenario have damaged the water pump? (I did the entire coolant system overhaul less than 2 yrs./15,000 miles ago - it's a 2000 328Ci with 132K on her), so I would not expect the WP to have dies of natural causes. I also did the vanos seals a few months back and it's been running great since, so I don't know that the vanos would be the culprit.

The rattle I have is much like that of the OP, but it also squeals a bit when I rev it - which makes me think it might be the tensioner. Anything else that might be causing it?

Found my rattle - it was a loose power steering pump. When I reinstalled it, I somehow swapped the screws and used the short one in front and the long one in back. Reversed them and solved the problem. Ended up replacing the belts and pulleys while I was at it. Fan still appears to be DOA though.