strange rattling noise from engine bay

acurael · 07-30-2018, 02:27 AM

Hey guys, 2008 bmw 335xi
started making this rattling noise a few weeks ago. Any idea what it could be? you can hear it come and go over the regular noisy engine.
thanks for your help

Volasko · 07-30-2018, 02:38 PM

You should try changing the RPM and see if the rattle frequency matches the higher RPM. If not my bet would be water pump related as it is an electrical pump. If you have an 06 you have the rest heater function, which you could use to test if the noise happens with the engine off (runs the water pump from the battery and HVAC motor to keep your cabin warm even when you leave your car).

acurael · 08-01-2018, 01:22 AM

thanks for the response

so it does not vary when I try changing the RPM as far as I can tell (although hard to hear as the engine is loud and i have the performance exhaust also)

I tried the rest button and the noise is not there. Its only when the engine is on.

so any other ideas? Is it the water pump likely or something else. I had the water pump changed around 90,000-100,000 km and i'm at 155,000km now.

acurael · 08-06-2018, 11:39 PM

any other ideas?

07-30-2018, 02:27 AM	#1
acurael Private 6 Rep 56 Posts Drives: bmw 335xi Join Date: Feb 2013 Location: vancouver BC iTrader: (0)	strange rattling noise from engine bay Hey guys, 2008 bmw 335xi started making this rattling noise a few weeks ago. Any idea what it could be? you can hear it come and go over the regular noisy engine. thanks for your help
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07-30-2018, 02:38 PM	#2
Volasko Colonel 705 Rep 2,605 Posts Drives: 06 330i E90, 18 530xe G30 Join Date: Dec 2010 Location: Toronto iTrader: (2) Garage List 2018 BMW 530e M Sport [9.00] 2006 BMW E90 330i [8.28]	You should try changing the RPM and see if the rattle frequency matches the higher RPM. If not my bet would be water pump related as it is an electrical pump. If you have an 06 you have the rest heater function, which you could use to test if the noise happens with the engine off (runs the water pump from the battery and HVAC motor to keep your cabin warm even when you leave your car).
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08-01-2018, 01:22 AM	#3
acurael Private 6 Rep 56 Posts Drives: bmw 335xi Join Date: Feb 2013 Location: vancouver BC iTrader: (0)	thanks for the response so it does not vary when I try changing the RPM as far as I can tell (although hard to hear as the engine is loud and i have the performance exhaust also) I tried the rest button and the noise is not there. Its only when the engine is on. so any other ideas? Is it the water pump likely or something else. I had the water pump changed around 90,000-100,000 km and i'm at 155,000km now.
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08-06-2018, 11:39 PM	#4
acurael Private 6 Rep 56 Posts Drives: bmw 335xi Join Date: Feb 2013 Location: vancouver BC iTrader: (0)	any other ideas?
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