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View Full Version : Rubbing/Rumbling/Grinding Noise From Rear of Beast(car)


Fetch
12-18-2006, 06:37 PM
I meant to make a thread about this when I noticed it a month ago, so here goes!

Sometimes when I start my 530 a couple seconds after it has been started/is idling, I will hear a low rumbling, very slight grinding noise from the rear trunk area of the car!

EDIT: Now that I think about it even more, it could maybe be classified as a bubbling gurgling noise too.

This is before I'm moving at all, so I have ruled out the diff & other drive line parts for this noise.

Please don't tell me it's the fuel pump....that'd be lame.
repenttokyo
12-18-2006, 06:44 PM
could it be a loose exhaust mount?
632 Regal
12-18-2006, 06:47 PM
agreed, see if the the muffler system is loose by grabbing the exhaust tipas and moving it. shouldnt be loose, might have 1/2 inch play all around or so.

could it be a loose exhaust mount?
Fetch
12-18-2006, 06:48 PM
could it be a loose exhaust mount?

Highly doubt it, as I just recently (few months ago) installed two missing rubber hangers & didn't noticed anything else loose on the exhaust.

I'm wondering if it's something with the evaporative system (is that what it's called?) bubbling air or something into the tank? I don't know much about that system though, obviously :p
Fetch
12-18-2006, 06:51 PM
agreed, see if the the muffler system is loose by grabbing the exhaust tipas and moving it. shouldnt be loose, might have 1/2 inch play all around or so.

I haven't done this recently lol, but I will try it again if two people insist! :)
shogun
12-18-2006, 06:55 PM
Before you start the car, remove the tank cap. if you can hear the hissing sound. If so, tank is under vacuum.
Fuel tank de-aeration system defect.
That was a big problem on E38, I have read about several cases that even the tanks cracked by vacuum.
632 Regal
12-18-2006, 06:58 PM
mine did the sucking sound, the thought of an imploding tanks made me get a new cap and problem fixed.

Before you start the car, remove the tank cap. if you can hear the hissing sound. If so, tank is under vacuum.
Fuel tank de-aeration system defect.
That was a big problem on E38, I have read about several cases that even the tanks cracked by vacuum.
Fetch
12-18-2006, 07:34 PM
Ok, the exhaust system is very tight, & I opened the take cap, no hissing but I'll try this again other times.

Something kinda important I forgot to mention about the noise: The noise stops after ~5 seconds...
So a couple seconds after the car is started, I hear the noise, then 5 seconds later it's done.

Hmmm....any other ideas?
Robin-535im
12-18-2006, 07:40 PM
Please don't tell me it's the fuel pump....that'd be lame.

Lame because you don't want to fix it or lame because you've already checked?

Do you have LAD? Hard to imagine what besides the fuel pump / fuel system there is that has any kinetic energy at standstill.

Maybe the GF had too many beans and is blaming it on the car?
BillionPa
12-18-2006, 07:41 PM
it was the fuel pump in mine, i added FP60 to every tank since and it has pretty much gone away.
Fetch
12-18-2006, 07:54 PM
Lame because you don't want to fix it or lame because you've already checked?

Lame because it costs money :p
Fetch
12-18-2006, 07:55 PM
it was the fuel pump in mine, i added FP60 to every tank since and it has pretty much gone away.

Interesting, you had similar noises?

Never heard of the FP60 stuff until I googled it
shogun
12-18-2006, 07:59 PM
here is a direct link, also have never heard of
http://www.lubecontrol.com/fuel.htm
BillionPa
12-19-2006, 02:06 PM
the main issue is the reduction of sulfur in gasoline. it was an excellent lubricant for pumps and injectors, but now there really isnt any at all, for many reasons. any good fuel lubricant additive will add longevity to the pump and make it shut up.

i have used the lucas ucl additive and FP60, and FP60 is the must fluid at low temps, so that is what i am currently using.
Fetch
12-19-2006, 07:25 PM
the main issue is the reduction of sulfur in gasoline. it was an excellent lubricant for pumps and injectors, but now there really isnt any at all, for many reasons. any good fuel lubricant additive will add longevity to the pump and make it shut up.

i have used the lucas ucl additive and FP60, and FP60 is the must fluid at low temps, so that is what i am currently using.


LOL, Hmmmmmmmmmm
So I can add sulfur to my fuel and save my fuel pump!!! However it will destroy my Nikasil linings........but the fuel pump will be ok!........:p

I probably will buy some of that FP60 stuff, thanks for the recommendation.