Chrissymeonides

Hello guys,

I have posted a video on Youtube, please have a look and give me your comments/thoughts.

The fact: One year old car (received it on September 2016). There is a strange noise coming beneath the case, looks like it comes from the exhaust system. It usually happens when the engine has been on for a while (more than 30 minutes drive) and while the engine is off, is like cooling down and this noise last for some minutes. It also happens when engine car is on, while on a ride.

The link:

takeapieandrun

My families 08 Lexus and previous 03 MDX did this after parking, I always assumed it was the exhaust system cooling and making noise from contraction. It's most likely the heat shields that make the noise, as they are thinner and contract/expand faster.

Chrissymeonides

if that is the case, should i worry for future issues?

Teckno

Agree it sounds like heat shield cooling down. Normally nothing to worry about, however neither of out 2 x 250d do this. What is your outside temps when you stop, if its very cool then maybe this is amplified, as out temps here in Oz are mild. It could also be loose screws/bolt holding heat shield in place, heat washer may have been lost and allowing greater mechanical range in contracting on cooling. Have it looked at next service, if not too long a wait. Slight tapping shield area when cold may give off a tinny , loose sound indicating bolt working loose. Best looked at when on a hoist and cool. Good luck, let us know how you get on.

Chrissymeonides

I have been told by an MB rep that the sound is generated after the Add Blue is sprayed in the exhaust system. The temperature in the system is high enough during the regeneration phase DPF and when sprayed with Add Blue the exhaust system is contracted......True or Not, i don't have a clue. And if this is a normal procedure, why not all GLC or MB diesel models do not generate the same sound?