Strange rumbling/groaning on startup

[killian665]

Every now and again, usually when the car is cold, when I crank it I get this strange rumbling/groaning noise from what sounds like the rear of the car. I can’t think of anything back there that would cause this short maybe the transmission pump and the sound is just reverberating around the car, but I’ve never heard one make that kind of noise.

Has anyone ever had this issue? If it’s not something obvious once i put the car on the lift then I’m just gonna pull the transmission pan and see what’s up.

[72tpik5]

Some strange groaning/gurgling sounds at start up have been diagnosed as the fuel moving from one side of the tank to the other.

[killian665]

That is the area it sounds like it’s coming from. Super annoying. Is something failing or am i just going to have to live with that? Because I’ll take it to the scrap yard right now if it’s just going to make that noise forever.

[72tpik5]

Mine has never done it, so I don't know what the fix is, if any. Hopefully someone who has experience with this will chime in.

[cartoonz]

put more gas in it?

[Higgilo]

My 850 does this at almost every cold startup. It is super annoying but I think it’s one of the quirks of the e31


Sent from my iPhone using Tapatalk

[killian665]

I don’t know, it couldn’t have done that when it was new nobody would have bought it. Gonna look around and see if I can’t find anybody else complaining about this

[Timm]

I've heard this said a few times - and I guess it is the suction jets (these pull the fuel from the LHS over to the surge tank):



They obviously are not meant to make any noise, and I doubt they ever made any noise when they were new.

So, my best guess is that air is getting in the return line when the car is switched off, and the noise is the air gurgling in the tank when the pump starts circulating the fuel - and stops when all the air is purged.

[killian665]

So I need to replace all that. I did that on my 540 once, it was pretty simple

[Timm]

It's only a guess as I've never heard the sound first-hand and it could be something completely different!

[killian665]

I’ll see if I can get a little video. I’m sure it won’t be much help but just for reference maybe somebody else will have this issue and recognize the sound. Might help em later on

[toomanyparts]

Does this present any real problem for the fuel system or is it just an audible annoyance. My car does it every now and then and has since I bought it. Never had an issue with the fuel system.