D5 (2005 on) Noise from oil filler cap - Vacuum leak

[Nickthecook]

Definitely have a vacuum issue that's causing slightly rough idle and a lot of extra engine noise. This is most noticable when you take the oil filler cap off. Pumped the brakes a few times and the noise vanishes, only to return a second or two later. I'm also getting some noise from the turbo area that resotates up to the air box.

Does anybody know if the vnt actuator could somehow be the source of the vacuum leak and the pop, pop sound from the turbo area? Both sounds vanish at about 1500-2000rpm. I know about the issue with the lifters on the early Euro4 engines and possible valve blow by. However, when I briefly get rid of the engine noise from the vac leak, there is very little tappet noise. The pop, pop still remains, though. It does die down significantly if the engine's given a good reving, but gradually returns after 60secs.

The turbo spools up fine and the car drives well, with no warnings from the computer. It had a new vac pump two years ago, before I owned the vehicle. Garage doesn't have a vac gauge, but said will borrow one to test the system tomorrow.

[5cilinder]

That sound is caused by the vacuumpomp wich has a leak somewhere in the circuit ,when the leak is solved sound is away
Provided that the sound is comming from the oilfillercap

Its methodicly testing the hoses and boxes on leaks : enginemounts could leak ,if they are leaking than sucking creates bublingsounds because they are filled with antifreeze

[Clan]

Originally Posted by Nickthecook

Definitely have a vacuum issue that's causing slightly rough idle and a lot of extra engine noise. This is most noticable when you take the oil filler cap off. Pumped the brakes a few times and the noise vanishes, only to return a second or two later. I'm also getting some noise from the turbo area that resotates up to the air box.

Does anybody know if the vnt actuator could somehow be the source of the vacuum leak and the pop, pop sound from the turbo area? Both sounds vanish at about 1500-2000rpm. I know about the issue with the lifters on the early Euro4 engines and possible valve blow by. However, when I briefly get rid of the engine noise from the vac leak, there is very little tappet noise. The pop, pop still remains, though. It does die down significantly if the engine's given a good reving, but gradually returns after 60secs.

The turbo spools up fine and the car drives well, with no warnings from the computer. It had a new vac pump two years ago, before I owned the vehicle. Garage doesn't have a vac gauge, but said will borrow one to test the system tomorrow.

The vacuum pump noise which is noticable when you take the oil cap off when idling is quite normal .. the pump sucks air from the servo , it has to get rid of it somewhere , it exits out the back of the pump into the cam cover area .. you will hear it from any D5 to the present day .

[5cilinder]

Originally Posted by Clan

The vacuum pump noise which is noticable when you take the oil cap off when idling is quite normal .. the pump sucks air from the servo , it has to get rid of it somewhere , it exits out the back of the pump into the cam cover area .. you will hear it from any D5 to the present day .

When yhere is a leak ther is a lot to dispose ,hence the noise
Without leak no/litle air to dispose and no noise (with my engine at least)

[Clan]

Originally Posted by 5cilinder

When yhere is a leak ther is a lot to dispose ,hence the noise
Without leak no/litle air to dispose and no noise (with my engine at least)

all the D5's i have heard when running with the oil filler cap off have a constant loud popping noise coming from within . also quite a lot of crankcase smoke rises out .

[cheshired5]

Originally Posted by Clan

all the D5's i have heard when running with the oil filler cap off have a constant loud popping noise coming from within . also quite a lot of crankcase smoke rises out .

Hi Clan.
Mine has this plus smoke at the dipstick at hot idle and the filler and dipstick tube will keep a latex glove inflated at idle but the smoke and "pops" disappear and create suction on the glove from about 1500rpm.
Is this normal?

[Clan]

Originally Posted by cheshired5

Hi Clan.
Mine has this plus smoke at the dipstick at hot idle and the filler and dipstick tube will keep a latex glove inflated at idle but the smoke and "pops" disappear and create suction on the glove from about 1500rpm.
Is this normal?

the smoke is normal even on new cars ... i have never revved one with the oil filler cap off so you are probably right . when idling the popping is constant ..

[5cilinder]

Originally Posted by cheshired5

Hi Clan.
Mine has this plus smoke at the dipstick at hot idle and the filler and dipstick tube will keep a latex glove inflated at idle but the smoke and "pops" disappear and create suction on the glove from about 1500rpm.
Is this normal?

Ofcourse
The reason smoke is comming out at idle is that the breathervalve is shut because there is no pressure difference due to the open hole where the gasses follow the path of least resistance , the moment there is pressuredifference it opens due to 1 crankcasepressure or 2 turbo suction or both

[5cilinder]

Originally Posted by Clan

all the D5's i have heard when running with the oil filler cap off have a constant loud popping noise coming from within . also quite a lot of crankcase smoke rises out .

I know that, but mine is silent when i blinded off a leak ,namely the egr cooler bypassvale is vacuum controlled and is used at warmup mine was broke after fixing it the vacuumpump is very silent

If you state that the popping sound is excess air wich is plausible then there has to be a leak somewhere at the vacuumside to provide that excess air
Without leaks no or much less air and hence less popping sound
Sounds logicall with your own reasoning

When i have time ill post a clip with the sound difference with or without leak

[5cilinder]

Originally Posted by 5cilinder

When i have time ill post a clip with the sound difference with or without leak

As promised:

Right after cold start

[YOUTUBE]https://www.youtube.com/watch?v=GsiM...ature=youtu.be[/YOUTUBE]