weird noise coming from engine bay

[danid40]

hey guys,
long time viewer, first time poster here.

i’ve got a 2007 spanish built d40 i bought about a year ago now, and over the past week it’s starting to make this loud rumbling airy noise whenever it’s on. i’ve called my mechanic but they can’t get me in for another week and a half so i thought i’d try my luck here.

the noise started only occasionally on start up, and then wouldn’t make it again the next time i started the car up. now it’s making it every time i start the car up. it gets higher pitched (but not squealing) when the rpm’s go up. i’ve checked my oil and it’s fine, going to check coolant in the morning when it’s cold. no overheating at all.

i’ve looked all over the internet for hours and can’t find the right noise/diagnosis.

it sounds louder in the cab than outside the car.

thought it could be wheel bearings but i replaced those about 6 months ago.

any help is greatly appreciated x

 

[Aaron31]

Overrun bearing on the alternator?

 

[danid40]

Overrun bearing on the alternator?

the alternator was replaced in feb 2023, would they have done the bearings then too? and how do you think i could double check and be certain? x

 

[MANNING]

My first thought when I heard "rumbling airy noise" was that you've had an intercooler hose either pop loose or you have a split in it.
Could be the intercooler hotside that runs from the right side of block to the intercooler up front.

Could maybe be the air hose from the air filter, or the filter lid.

Our I thought maybe the egr?

 

[Aaron31]

To determine if its an accessory or not (i.e. alternator, air con etc), take off the belt(s) and start it - it will narrow it down pretty quick.

 

[danid40]

hey guys,
long time viewer, first time poster here.

i’ve got a 2007 spanish built d40 i bought about a year ago now, and over the past week it’s starting to make this loud rumbling airy noise whenever it’s on. i’ve called my mechanic but they can’t get me in for another week and a half so i thought i’d try my luck here.

the noise started only occasionally on start up, and then wouldn’t make it again the next time i started the car up. now it’s making it every time i start the car up. it gets higher pitched (but not squealing) when the rpm’s go up. i’ve checked my oil and it’s fine, going to check coolant in the morning when it’s cold. no overheating at all.

i’ve looked all over the internet for hours and can’t find the right noise/diagnosis.

it sounds louder in the cab than outside the car.

thought it could be wheel bearings but i replaced those about 6 months ago.

any help is greatly appreciated

hey guys, thank you for all the help. i found what the issue was when the alternator pulley launched out of the car at mach jesus as i was pulling into my driveway thankfully nothing else was damaged except for the pulley

 

[ericcs]

that's a common problem, have changed the clutch pulley 3 times on mine. first time, the shaft broke.

 

[Nig]

To determine if its an accessory or not (i.e. alternator, air con etc), take off the belt(s) and start it - it will narrow it down pretty quick.

Spray the belts with soapy water will give you a good idea where you are going.