Faint rattling noise when pulling away @ ~2k rpm

mrk

mrk

mrk

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When pulling away a metallic (as if something metal is tapping against something else) rattling sound can be heard coming from the centre top/middle engine bay section from inside the car, with the windows open it’s less apparent but with them closed it is audible up to around 2500-3000rpm in any gear. If I sit idle and rev the car to that range with the hood up then there is no noise so it can only be heard when pulling away. I guess the only way to hear where it's coming from is to put it on a rolling road?

I have Googled and found this post from a guy with an M3 who describes the exact same sound I have except of course mine is not an M3 and I would not have thought fuel type would have mattered as much on a 2litre 4cylinder so may well be something the E46 line share in common

It’s only started a few weeks ago, at least I only started noticing it a few weeks ago anyway and I’ve been filling up at Texaco, Tesco, Sainsburys and Shell between fillips with the occasional 99ron fillup every now and then (Tesco 99 and Sainsburys 99).

Other than the noise there is nothing else odd when driving and fuel economy is no different from before. An inspection 1 was done about 4k miles ago (miles is ~58k) with no real issues noted other than a lack AC or coolant service record on the dealer’s computer.

I’ve had a look inside and did not spot any loose bits or leaks or anything.

The noise is not obtrusive but is a bit annoying (:p) and I doubt anyone other than the driver of any car making this noise would notice it so maybe I should follow the Op’s dealer’s recommendation and fill up the next few tanks with vpower?

Anyone who’s had an E46 had this kind of issue before?
 
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I know its not the same car or even engine, but i had a similar problem with my engine, pulling away at around 1.5 - 2k the car would make a rattle, this eventually became a cog grinding noise.

I changed my clutch and flywheel (which needed doing) thinking this would fix the issue but it didn't, after much digging around it turned out to be the cam tensioner on the exhaust side of the car, which in mine is located at the back of the engine (closest to the cabin) its a hydraulic driven vvt solidnoid, i know its a longshot but it might be worth checking to see if your engine has something similar, thats provided its not a heatshield making your noise.
 
Water pump? Sounds exactly like what I had happening on my 2001 330i. Circa £300 to fix at local BMW dealer.
 
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300 inc labour? that should work out a fair bit cheaper at my dealer I reckon if that is the issue but still, a bummer having just spent 420 on tyres!

Thanks firestar too, I think it will probably have to be booked into the dealer sometime soon to confirm which of the two (or something else) it is because it looks like something outside of the realms of DIY :(

Well if it's not the heatshield of course!
 
Yeah £300ish (I think total was £33x somthing, haggled them down a little from the orignal £370) incl. labour, was there for about 3 hours.
 
Looking online, a waterpump is around £85, they charged a lot for labour^ :O
 
They did indeed, but I just turned up on the Saturday morning with a rattling engine and asked them to fix it (as I had had the car for 3 days, I didn't know WTF was wrong with it).

* Although £80 odd pounds an hour isn't too bad.
 
Ah cool, mine is 60 an hour but it's finding the time to go down and get it diagnosed which is the problem, will have to shift time around on Sat I think :/
 
Get a Long flat bladed screw driver & use it like a stethoscope to locate the noise, Just hold the handle to your ear gently touching the bone in the side of your face in front of your ear then place the tip on the bit of the lump you want to listen to moving it around to locate the noise. This will at least help in diagnosing the problem rather than just throwing 300 quid on a guess.
 
malc30 said:
Get a Long flat bladed screw driver & use it like a stethoscope to locate the noise, Just hold the handle to your ear gently touching the bone in the side of your face in front of your ear then place the tip on the bit of the lump you want to listen to moving it around to locate the noise. This will at least help in diagnosing the problem rather than just throwing 300 quid on a guess.
Click to expand...


Would this work effectively? I guess it depends on the screwdriver in question though as I have rubber handles ones!
 
Of course it works :p
You'll need a rigid handle though to transmit the sound properly.
 
Better not be pulling my arm, I'll look a fool sticking my jaw to a screwdriver touching the engine!
 
I am surprised you haven't seen a mechanic use the technique previously, just try it on your drive, You'll feel the vibrations & be able to pick out sounds much better than just standing over the engine.
 
When I owned my e36 328 it had a slight rattle when pulling away, this was the heatsheild, the fixings are poo and the heatsheild just came away. Could this be the same thing? Easy and cheap to fix if it is!

Rob
 
ardy89 said:
When I owned my e36 328 it had a slight rattle when pulling away, this was the heatsheild, the fixings are poo and the heatsheild just came away. Could this be the same thing? Easy and cheap to fix if it is!

Rob
Click to expand...

Hmm, do you have a quick diagram of where to look for the fixings in particular? or is it all of them in general? :S
 
Is it definitely from within the engine bay? I've had problems like this a couple of times and it normally turns out to be exhaust related. The heat shield could be likely although I dont know the car in question so dont know how its laid out...
 
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