Diesel fumes through air vents

[chris900]

2009 V70 2.4 D5

Guys, I have a smell of diesel fumes (not raw diesel) through the front air vents only. The windscreen and foot vents are absolutely fine and there is no problem when I use them and keep the face vents closed. I know some folks talk about the PCV but my rationale is that if that is a problem then it would apply to all vents. I could be wrong, hence the reason for asking. Any ideas?

[Kev0607]

Have a look under the bonnet. Take the engine cover off & see if there's any oil misting on any of the pipes - Do this whilst the engine is warm, you may even see or smell the source. It could also be a cracked manifold, or an exhaust leak maybe? A blocked EGR may also cause a fumes smell & the PCV could be suspect. Have you added any oil to the car, or had it serviced recently? Something simple as oil spillage on a warm engine could be the cause.

A bit to inspect, but have a good look & sniff around

[chris900]

Originally Posted by Kev0607

Have a look under the bonnet. Take the engine cover off & see if there's any oil misting on any of the pipes - Do this whilst the engine is warm, you may even see or smell the source. It could also be a cracked manifold, or an exhaust leak maybe? A blocked EGR may also cause a fumes smell & the PCV could be suspect. Have you added any oil to the car, or had it serviced recently? Something simple as oil spillage on a warm engine could be the cause.

A bit to inspect, but have a good look & sniff around

Thank you Kev. That gives me something to go on. If the PCV was the culprit would the smell be experienced through all vents?

[Kev0607]

Its hard to say really. However, a common technique to test the PCV is using a rubber disposable glove:

1. Start the engine & let it run for a little whilst so its warm. However, keep the engine running whilst you do perform the next steps.

2. Remove your oil filler cap, put a disposable rubber glove around the neck of the fillter cap & you can use an elastic band to hold it in place if you wish.

3. If the glove inflates, the PCV is clogged because the pressure is building up towards the top of the engine. If its not blocked, the glove will simply stay deflated in its original state.

Its a simple test, but it should show you if there's a problem with the system. Ant on Wheeler Dealers used the same method when he was working on a PCV system on a 850 T5 R, if I recall correctly.

Edit: Your car is a D5. I think the PCV is a common issue on petrol models. I think the D5’s are different, or maybe don’t have a PCV at all? I’m not sure about that to be honest.