Do diesels smoke more as they age?

[The motor guy]

This is gonna sound kinda weird but I noticed the garbage truck that goes through our neighborhood used to never smoke and lately it's been creating a light haze of black smoke when it accelerates. This same truck has been coming through the neghborhood for the last 4-5 years. So I was wondering do diesel engines start to smoke more when they get more miles on them? Before all you would see is the clear exhaust heat coming out. Oh and btw i've always had an interest in big diesel trucks like semis and that sort of thing so that's why I noticed this.

 

[gathermewool]

I'd bet it has more to do with maintenance than it being an inherent diesel problem.

There's a latest-gen TDI Jetta around my way with black, sooty rear bumper that spews out black smoke at the slightest acceleration. In this case, I'm not sure if it's the pee injection system or an oil-related motor issue. Either way, it's most likely due to lack of maintenance.

 

[artificialist]

Originally Posted By: gathermewool
I'd bet it has more to do with maintenance than it being an inherent diesel problem.

There's a latest-gen TDI Jetta around my way with black, sooty rear bumper that spews out black smoke at the slightest acceleration. In this case, I'm not sure if it's the pee injection system or an oil-related motor issue. Either way, it's most likely due to lack of maintenance.


I thought that no VW Jetta was built with urea injection.

 

[rpn453]

It's burning a bit rich if you're seeing smoke. Injector wear could contribute to that.

 

[gathermewool]

Originally Posted By: artificialist
Originally Posted By: gathermewool
I'd bet it has more to do with maintenance than it being an inherent diesel problem.

There's a latest-gen TDI Jetta around my way with black, sooty rear bumper that spews out black smoke at the slightest acceleration. In this case, I'm not sure if it's the pee injection system or an oil-related motor issue. Either way, it's most likely due to lack of maintenance.


I thought that no VW Jetta was built with urea injection.


I have no idea, just guessing.

 

[CROWNVIC4LIFE]

A friend has a 2000 M Benz diesel with 170 miles..He is the original owner..It does not smoke at all..The car is dealer serviced every 3K miles..His dealer only uses mineral oil and told him NEVER to use synthetic..His driving is mostly stop and go but it he does get out on the highway for about 50 miles once a week.

 

[antonmnster]

Some of the diesel equipment at work seems to smoke more with high hours (like >7000)

Power is down, too. I thought compression is starting to go, and the burn isn't as complete.

I'm no expert, but I'm sure there are a lot of reasons.

 

[Shannow]

If the injectors start throwing a stream, or dropletts in stead of a fine mist, power will be down and smoke up, even if the engine is still running lean.

There's just not enough time to get the air to all of the fuel.

 

[Silk]

Diesels will give black smoke when injectors get worn,but there is no such thing as rich or lean with a diesel. They nearly always have enough air,but excess fuel usually means there is just not enough time to burn all the fuel,and the black smoke is partially burned fuel. Unburned fuel is white smoke.

I've noticed since we have gone to ULS diesel that the bad black smokers have almost disappeared. It took a few years,but I hardly ever see a heavy smoker now. I used to have a Pajero that put out black smoke under load,even with rebuilt injectors and pump,and correct timing. After a year or 2 on ULS fuel it hardly smoked at all....I changed nothing at all.

 

[Shannow]

They are always lean of stoichiometric, so lean/rich is comparative, not absolute.

 

[NateDN10]

Originally Posted By: gathermewool
There's a latest-gen TDI Jetta around my way with black, sooty rear bumper that spews out black smoke at the slightest acceleration. In this case, I'm not sure if it's the pee injection system or an oil-related motor issue. Either way, it's most likely due to lack of maintenance.

My guess is that the owner removed the DPF and retuned for more power. At least that's usually the case when you see late model diesel pickups that smoke on acceleration.

Interestingly, my father recently bought an '11 Jetta TDI. The salesman put a white rag over the tailpipe on a 2.5L and the TDI, and the rag on the gasser collected some soot while the TDI was completely clean.

 

[mechtech2]

Diesel:
Black smoke fuel problem.
White smoke usually oil - maybe turbo seals.

Three white smokes, and we have a new Pope!

 

[lexus114]

Originally Posted By: mechtech2
Diesel:
Black smoke fuel problem.
White smoke usually oil - maybe turbo seals.

Three white smokes, and we have a new Pope!


That was good, I like that one.

 

[DrDusty86]

BLACK smoke is UNBURNT diesel fuel. I have put chips on my diesels since my 98.5 CTD with 430hp injectors she would throw enough black smoke that people thought the truck was on fire..OH how I LOVED to do it to tailgaters.. The TDI might have simply had a tune.. nothing more. The Spartan tuner on my PSD said in HI-PER it's a 275HP tune..Man.. that Beautiful smoke and that turbo of a straight piped 6L
Those that claim BLACK smoke is oil are talking out of their back sides
Dusty

 

[DrDusty86]

To answer the op's question, it more than likely is the IP or the injectors..assuming the company didn't chip em

 

[rpn453]

Originally Posted By: Shannow
If the injectors start throwing a stream, or dropletts in stead of a fine mist, power will be down and smoke up, even if the engine is still running lean.

There's just not enough time to get the air to all of the fuel.


Well said!

 

[hattaresguy]

If they are not running right, or tuned to put out a lot of power. Black smoke means over fueling, and on older diesels its quite normal when you get on it quickly since the fuel increases faster than the air can, so they over fuel as they spool up.

On my old 603 I liked to run the timing 1 degree advanced with the ALDA backed off, and it would put out a nice puff of smoke at WOT. The side benefit was I gained a second 0-60, well and I had a couple other minor tweaks.

 

[gathermewool]

Originally Posted By: DrDusty86
BLACK smoke is UNBURNT diesel fuel. I have put chips on my diesels since my 98.5 CTD with 430hp injectors she would throw enough black smoke that people thought the truck was on fire..OH how I LOVED to do it to tailgaters.. The TDI might have simply had a tune.. nothing more. The Spartan tuner on my PSD said in HI-PER it's a 275HP tune..Man.. that Beautiful smoke and that turbo of a straight piped 6L
Those that claim BLACK smoke is oil are talking out of their back sides
Dusty


I hate jack and aces with smoke tunes.

Oh, and the TDI Jetta around here is being driven by a middle-aged lady, so I doubt she's into tuning.

 

[JTK]

The Freightliner tractors we have at work have so much emissions stuff on them, they barely let out a wisp on cold start. Most have 500-600K miles on them. Some have Mercedes diesels in them, most are Cummins I believe.

Joel

 

[SteveSRT8]

I just recently watched a tuned up Dodge diesel get pulled over for belching so much black smoke it was hazardous!

I run an aggressive aftermarket tune in my car but you can still see behind me! I certainly hope this gets squashed hard by the cops.