Bang noise coming from under car.

[meldean]

Hi everybody.

I have a 2.0 tdi and i have started getting a banging noise from under car. The noise happens when the car is stationary as well as moving and i have pinpointed the noise to be coming from under drivers seat but under the car.

I have looked under car today and can see what looks like a radiator or cooling block and the noise seems to be coming from that.

Can anybody advise what this is and what could be causing the bang.

I am thinking it is something to do with aircon.

Any advise very much appreciated.

Last thing. It only does it like 5 times and within first 5 minutes of the journey and then stops.

 

[SmithyAG]

If it looks like a radiator on the bottom of the car, it's more than likely the fuel cooler.

Could the noise be the in tank fuel lift pump beginning to get tired?

 

[meldean]

I am not sure to be fair. I am a new owner of a diesel lol

I must admit though it does sound like a pump noise in the rythm of the noise.
Its defo not coming from the fuel tank though.

If it was a the fuel pump in tank i would have thought it would have done the noise all the time. Which it doesnt it only last 5 mins and then stops.

 

[meldean]

Anybody else with any ideas on this please. Can the fuel cooler make a banging noise. I have checked to make sure its not loose and it is solid. Is there anything else near that can cause a banging noise.

 

[meldean]

Anybody at all have any other ideas.

 

[phil76]

Has the bracket for the fuel cooler bust ? if so just cable tie it back up as a temp fix

 

[meldean]

No the fuel cooler is not loose at all. I check that first thing.

Baffling the hell out of me. Im wondering if there is any pipes under the belly plate near cooler that could be banging when fuel is getting pumped through fuel cooler. I just find it weird that it only does this within first 5 minutes of the journey. If i stop and turn engine off and leave for lets say 10 mins. It will start again. Lol

 

[y2kcurran]

Does it sound more like a 'thump' than a bang? I have the same car and first noticed a weird 'thump' right under my feet when I had switched the car off after a long drive, I actually felt it through my feet, it felt like an animal had ran under it and hit it's head! But then I noticed it would happen every 20 seconds or so for a few minutes, I've been meaning to really look into it but haven't had the chance recently. From a quick search though i'm assuming it does have to do with the air con, i've read it's to do with a compressor releasing pressure? Maybe someone with more working knowledge of air con can confirm. I've noticed it doesn't happen when I have 'Econ' selected which would then make sense.

 

[meldean]

Yes it does sound like a thump. A repeated thump and then stops. Thought i was on my own with this then. Lol

I have my aircon on auto and econ on and it does it. Will try differant combos and report back any changes.

 

[meldean]

Update on the thump.
I have tried turning aircon off totally. With and without econ on and i still get a random thump.
I drove all the way home from manchester today. Total of 60 miles with nothing with not 1 thump.
Parked car up for 30 mins. Started back up and thump before i started moving and thump whilst i was moving.

Seems that when the car is warm it happens the most. Very confused as to what is causing this.

Its defo not suspension related or anything like that as the car does not have to be moving and no matter what toad surface i drive on i cannot make the noise happen.