[maswastage]

Are modern common rail direct injection diesels susceptible to carbon buildup like gasoline DI engines are? I was told that the properties of diesel fuel make diesel engines immune to this problem, but I'm wondering if maybe I have the wrong information.

[F32Fleet]

I've wondered that myself, I have 335d crossing the atlantic right now and I looked into this prior to ordering. I could not find any instances where the engine (M57TU2D30) suffers from intake coking. I've read that the "EGR" system is heated which I'm guessing was done to help prevent coking. IIRC there was a coking problem on the engine used for the 320d and possibly previous variants of the M57 (M57 block has been around since 1998). I know some older generations of the VW TDI sufferred from coking, but the newer model ('09 Jetta/Sport Wagon to present) is not supposed to have it either. I've read that volvo has some problems as well. IMO it's the cars which spend most of their life in city traffic that have developed the problem.

The UK forum is a good place to ask.

[maswastage]

I remember asking around the UK forum about reliability before I ordered my own car. I don't remember them citing any specific issues, but then again I wasn't asking very specific questions. I'm hoping this will be a non-issue, or at least it won't be more than a good engine/fuel system cleaner can handle.

Congrats on the purchase, you're going to love it! 425 lbs-ft will feel like a freight train, it's like a religious experience

[Quasimodem]

Hmmmmmm

[floydarogers]

Originally Posted by maswastage

Are modern common rail direct injection diesels susceptible to carbon buildup like gasoline DI engines are? I was told that the properties of diesel fuel make diesel engines immune to this problem, but I'm wondering if maybe I have the wrong information.

It has nothing to do with the diesel quality. The surmise is that the EGR (Exhaust Gas Recirculation) system causes the problem by putting exhaust gases that contain "junk" into the intake runners.

[Hoooper]

on gas engines it doesnt have anything to do with fuel/fuel quality either.

[Quasimodem]

You guys did look at the date on the OP right?

I guess I missed this post when I ordered my car in late 2008. I had no idea the carbon buildup was an issue back then.

Edit: In all fairness to myself, I did order my car a year before this post.... But still, I came across this old post doing a search. I hadnt realized the issue was discussed back in 2009.

[floydarogers]

Originally Posted by Quasimodem

You guys did look at the date on the OP right?

I guess I missed this post when I ordered my car in late 2008. I had no idea the carbon buildup was an issue back then.

Neither did anyone else.

[Hoooper]

Originally Posted by Quasimodem

You guys did look at the date on the OP right?

It was a setup!

[Jffeijao]

Originally Posted by Hoooper

It was a setup!

Guys,
Cool down, push your rigth foot and smile
Nothing is forever, things get old and wear.

Noted that all of us would like a better reliability from our Ds, but suffering in advance takes the ownership pleasure away.

[335dFan]

Originally Posted by Jffeijao

Guys,
Cool down, push your rigth foot and smile
Nothing is forever, things get old and wear.

Noted that all of us would like a better reliability from our Ds, but suffering in advance takes the ownership pleasure away.

That's right...good attitude. I've decided not to worry about it ahead of time. Just like Scarlett in Gone with the Wind.

But go easy on the "nothing is forever, things get old and wear" part; I'm getting up in years and that strikes too close to home.