Soot in exhaust of TDI

[wheelman]

I admittedly do not know much about these VW common rail engines. However on a VW Facebook group there is this theory going around that your exhaust should be spotless and if it isn't and there is any soot you have a cracked dpf. I understand the logic to a point but isn't that almost impossible? Seems like some soot/dirt debris etc is going to get in there. Anyway wanted your thoughts my car is a mk6 Jetta but this is apparently true for all dpf systems I took a picture of my exhaust and the "spot".

 

[OneLonelyBurrito]

Yeah you have a failure of some kind at the DPF. Some small amount of soot can get through a DPF, but nothing like that. They failure doesn't have to be a cracked DPF, I have also seen slipped DPFs where the DPF substrate moves inside the canning.

 

[wheelman]

Yeah you have a failure of some kind at the DPF. Some small amount of soot can get through a DPF, but nothing like that. They failure doesn't have to be a cracked DPF, I have also seen slipped DPFs where the DPF substrate moves inside the canning.

Can you elaborate on the comment "nothing like that" the black on my finger is after running my finger with firm pressure inside of both exhaust tips. The inside of the exhaust looks pretty clean.

 

[OneLonelyBurrito]

You shouldn't really be picking up any soot on your finger tip in the exhaust after the DPF. DPFs don't filter perfectly, but they catch basically all of the large particles that would accumulate on the exhaust system wall.

 

[RooflessVW]

The only option you have for an economic repair is to take it to a VW dealer... so you're at the mercy of their decision.

 

[wheelman]

The only option you have for an economic repair is to take it to a VW dealer... so you're at the mercy of their decision.

How would that be economical? I'm not convinced there is even anything wrong.

 

[RooflessVW]

How would that be economical? I'm not convinced there is even anything wrong.

Because presumably you still have some dieselgate warranty remaining.

 

[Big E]

When I check the tailpipe on my dpf equipped Cummins Ram I get NO soot on my fingers.

This has been the case also with the medium and heavy duty dpf equipped trucks I used to drive at work.

 

[wheelman]

Because presumably you still have some dieselgate warranty remaining.

Pretty sure it's out by a few thousand miles. Even if I took it in I bet they'd say nothing's wrong. Even if there is they'd probably blow it off since it's not "bad enough".

 

[wheelman]

When I check the tailpipe on my dpf equipped Cummins Ram I get NO soot on my fingers.

This has been the case also with the medium and heavy duty dpf equipped trucks I used to drive at work.

So if you run your finger in the exhaust it'll be perfectly clean?

 

[wwillson]

the black on my finger is after running my finger with firm pressure inside of both exhaust tips. The inside of the exhaust looks pretty clean.

There will be a slight amount of soot in the exhaust tract after the DPF. The inside of your exhaust pipe looks clean to the camera, but when you wipe with your finger you get some soot, not much, but some.

You shouldn't really be picking up any soot on your finger tip in the exhaust after the DPF.

This simply isn't true. I have owned several diesels with DPFs and they all exhibit the same soot inside of the exhaust pipe. The pipe will look clean and is mostly clean. Wipe the inside with your finger or a cloth and you will get a bit of soot, always.

Anyway wanted your thoughts my car is a mk6 Jetta but this is apparently true for all dpf systems I took a picture of my exhaust and the "spot".

My opinion is, what you are seeing is perfectly normal.

 

[wwillson]

When I check the tailpipe on my dpf equipped Cummins Ram I get NO soot on my fingers.

Try a white cloth, I promise you will get some.

 

[wheelman]

Try a white cloth, I promise you will get some.

I'd be curious if you did this what you find.

 

[OneLonelyBurrito]

I'm wondering if the jetta has a cordierite dpf vs a silicon carbide dpf. Cordierite is more likely to leave soot like that vs a silicon carbide dpf. Most of my experience is with silicon carbide dpfs, which haven't left any amount of soot that I have noticed.

 

[Big E]

Try a white cloth, I promise you will get some.

OK, I stand corrected.

I just wrapped my fist in paper towel and shoved it up the tailpipe as far as I could go. There was a very small amount of soot on the towel. Nothing like the OP's pictures. Which was the point I was trying to make.

 

[wheelman]

OK, I stand corrected.

I just wrapped my fist in paper towel and shoved it up the tailpipe as far as I could go. There was a very small amount of soot on the towel. Nothing like the OP's pictures. Which was the point I was trying to make.

Do you have a picture?

 

[dumkid]

that does seem like more soot than normal, as long as your dpf don't plug or throw a cel i wouldn't worry about it unless you still have warranty.

 

[wheelman]

that does seem like more soot than normal, as long as your dpf don't plug or throw a cel i wouldn't worry about it unless you still have warranty.

Still regens pretty regularly and all seems well.

 

[wheelman]

 

[Big E]

Not saying you have a problem or not. Just trying to give you something to compare to.

A more valid comparison would be another VW.