D5 158kw 2015 tapping/knocking sounds

[MartinKarafin]

Originally Posted by MartinKarafin

I haven't had much time to diagnose it, but i've talked to people and found somebody who was chasing a similar noise on a XC60. After replacing many things it turned out to be a very small leak between the head and exhaust manifold.

Will try to listen to the manifold with a stethoscope this weekend.

Did an oil change and afterwards pulled off the turbo heatshields. Access wasn't great but managed to get the stethoscope on the exhaust manifold. Nothing, no noticeable knocking. So i'm also out of ideas.

[Zafree]

I have visited 7-8 workshops so far and no one has any idea...
I do not know, but it seems to me that this is not such a rare problem with the 2015-> D5 engine

[Matej Mihelic]

Hello,
I have the same problem with my S60 D5 158kw my12. I have noticed the engine is running quieter when dpf is regenerating. Did any of you noticed that?

[MartinKarafin]

Originally Posted by Matej Mihelic

Hello,
I have the same problem with my S60 D5 158kw my12. I have noticed the engine is running quieter when dpf is regenerating. Did any of you noticed that?

I haven't had a chance to listen to the engine at idle during regen.
But i have noticed it is considerably louder during acceleration when regenerating.

[Lancee]

Vacuum pump ? Is there a slight vacuum leak anywhere ?

[5cilinder]

Originally Posted by Matej Mihelic

Hello,
I have the same problem with my S60 D5 158kw my12. I have noticed the engine is running quieter when dpf is regenerating. Did any of you noticed that?

Its not only noticeable its a feature
The goal with regeneration is to raise exhaust temperature its been done by retarding the injection timing, smear out the time of the injection (by lowering railpressure) and a post injection.
if you retard the injection starting point then there is less expansion possible because already before the injection there is already some expansion occured
Because of the less expansion possible there is less heat extracted of the burned fuel hence a higher exhaust temperature , where also a post injection will occur to raise the temperature even further.

The injection retarding and smearing out the injection pulse will drasticly lowering the peak pressures in the cillinder hence the noise and vibrations will temper.... in a already good functioning engine .... but if there is already something wrong with the injection timing or callibrated flowing of the injector(s) this effect will be magnified and more noticable

For instance in my normal functioning engine (2006 engine) its noticable not so much in noise ,but more in smoothness

[Matej Mihelic]

No leak at all. I’ve changed diaphragm on vacuum pump, and it’s little quieter, but still knocking present.