# 540 Low End Knock



## LeadFoot (Jul 15, 2004)

My 2001 540i had just a hint of a low end knock when purchased at 37,000 miles. I figure the car was driven pretty agressively since it has the Dynan performance chip installed. I drive the car fast, but not hard, but the knock is progressively getting louder at 79,000 miles. 

Best I can tell by listening with a solid rod and stethescope, its a low end knock. I run Valvoline synthetic 5w 30 oil and change every seven thousand miles (lots of highway driving).

Any recommendations on what the problem, and fix are ? Hopefully my worst suspicion is wrong, but I highly doubt it....

I've never been a proponent of oil additives or the like, but was wondering if at a minimum an additive may help quiet it down a bit, understanding that if it is a rod or bearing knock that the additive isn't the fix. Are there risks running additives in BMW engines given the tight tolerances, etc. ? :bawling: 

Leadfoot


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## chivas (Aug 31, 2002)

it's a known issue and BMW says it's fine... yeah.. right.

i get it once in a while. sometimes worse then others. i get it really bad when i'm in an incline. the atm near me points a bit up and when i'm getting cash, i swear i'm driving a diesel.

i figured this out when one day i went to the realtor's place and i pulled up on her driveway and her car was in there. i put my window down to talk to her and i hear the knock.. real bad. i pulled out of the driveway and back on the road where it's flat and it went away.

rumor has it that the motor in the E39 sits tilted back so it could be the front rods knockin'.


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## Ågent99 (Jan 7, 2002)

long shot but try some different gasoline...higher octane maybe?? :dunno:


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## chivas (Aug 31, 2002)

Ågent99 said:


> long shot but try some different gasoline...higher octane maybe?? :dunno:


$2.50 a gallon i'd rather just live with the knock if gas was the case.


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## SergioK (Aug 14, 2002)

I'd try some Lubro Moly Sauber Ventil.










Bav Auto sells it... search for Part # : 2002.


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## businessman_b (Aug 19, 2004)

Just a thought...but mine was making a similar noise. I searched for the origin of the knock and it turned out to be my a/c compressor.


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## bk540sport (Mar 8, 2004)

LeadFoot said:


> My 2001 540i had just a hint of a low end knock when purchased at 37,000 miles. I figure the car was driven pretty agressively since it has the Dynan performance chip installed. I drive the car fast, but not hard, but the knock is progressively getting louder at 79,000 miles.
> 
> Best I can tell by listening with a solid rod and stethescope, its a low end knock. I run Valvoline synthetic 5w 30 oil and change every seven thousand miles (lots of highway driving).
> 
> ...


Hello, check your spark plugs, and make sure there tight, i know it sounds dumb, i had a low end knock as well, i thought it was my grank breaings, but i was a couple of lose spark plugs that were letting blow by happen


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