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Muffled clunk from Fuel tank ?

Z3 Roadster (E36/7) 
2K views 4 replies 5 participants last post by  vintage42 
#1 ·
I have a 2000 Z3 which I recently acquired. I noticed an infrequent muffled clunk coming from what appeared to be behind my passenger seat ( its a RHD - Australian delivered car). I checked all the usuals .... bottle of wine rolling around in the boot (no such luck) etc. Then I feared suspension issues but when I took it to the garage they could find nothing wrong although did acknowledge that the issue existed.

They suggested that it was something 'loose' inside the fuel tank (it does seems to be more frequent when the tank is full of fuel) and offered to kindly relieve me of a couple of thousand dollars to install a new tank ..... on the off chance it might fix it .! Needless to say I declined.

Has anyone experienced this, does anyone know where the mystery sound is coming from ? any insight, suggestion or plain old guess greatly appreciated !
 
#2 ·
#3 ·
gas rocks

we don't often have this problem in the states but in some countries the refineries don't remove all the gas rock spores during fuel processing. over time, a gas rock can form in your tank and grow to the point that you hear it rolling around.

i'm not sure how to remove a gas rock, never having encountered the difficulty, but you might check with a local geologist. i'm sure they're familiar with the phenomena.
 
#4 ·
Try tightening slack on the emergency brake cable. Know intermittent clunky sound.
 
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