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Old 08-04-2005, 12:16 PM   #11
Registered User
Join Date: Jan 2004
Location: Happyland, Ontario, Canada
Posts: 1,173
My Ride: 09 Altima Cpe
Originally Posted by 328idriver
sometime at idle i get a knocking sound from the engine compartment usually..its very intermittent it comes and goes, seemingly with no regularity,the car is a 328i and its got 90,000 on it very good condition very well maintained, im wondering if the water pump is going? no leaking coolant that i can see,normal operating temps, but occasional knocking that isnt loud like engine knock and it comes and goes so its not like my motors about to go, it hasnt happend in like 1 month and yesterday it happend again wonder if the bearing in the pump are shot... No obvious clues, can someone shed some light and let me know more about the sound that a failed waterpump would emit. thanks-
I get a knocking sound at low RPM from the AC compressor - AC still works, but it makes one hell of a whacking sound at 800 to 1200 RPM. It will only happen when the AC button is on, so if you hear the noise try turning off the AC to see if it goes away.

From what I've heard, the WP will make more of a grinding noise when the bearings are going bad.

I will be doing the WP tonight or Saturday, parts are coming in tonight. BMW wants $160 plus $50 core charge, local auto parts store wants $90 plus $20 core charge (CDN) and they are BOTH rebuilds.

Has anyone seen an E46 WP with a plastic impeller (either the old one from your car or the new one)? Didn't they have problems with these in the E36?

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