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dogvetia

moville iowa usa

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Posted: 09/14/20 09:39am Link  |  Quote  |  Print  |  Notify Moderator

I need advice from some of you diesel experts. I have a cummins ISB 300 horse with 115,000 miles. Beginning 2 years ago when I accelerated away from a stop sign it would puff out some black smoke. Now 15,000 miles later it is much more pronounced and even at an idle you can see a small amount of black smoke. Just changed oil and in 10,000 miles used 3 quarts so I don't think this oil consumption is excessive for a 16 year old unit with that many miles.
I will take to Freightliner for a diagnosis but was thinking dirty injectors. Any thoughts? Any ideas for effective injector cleaners?
Thanks in advance Tom


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rgatijnet1

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Posted: 09/14/20 09:51am Link  |  Quote  |  Print  |  Notify Moderator

Usually an indication that your engine is running rich, or using more fuel than it can burn efficiently. This could be from worn out injectors that have an enlarged hole or other things that are putting more fuel in to the cylinders than the engine needs.

wolfe10

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Posted: 09/14/20 11:07am Link  |  Quote  |  Print  |  Notify Moderator

Could also be low turbo boost (less air for the same/old amount of fuel).

Could be: turbo, cracked exhaust manifold, leak in the CAC, leak in plumbing from turbo to intake manifold, or plugged air inlet/filter.

I would sure start with a visual check. Found a bird's nest in the coach-side air inlet on a coach where he had already spent thousands of $$ on "fixes".


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naturist

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Posted: 09/14/20 06:01pm Link  |  Quote  |  Print  |  Notify Moderator

I’d check the entire intake for blockages, starting at the open end all the way to the intake valves. It’s not a Cummins, but my 2001 VW Jetta diesel has a rodent blocking screen at the intake end under the wheel well. That screen keeps the squirrels out, a good thing, but it also catches leaves and other stuff and can restrict airflow if not cleaned out from time to time. It also has an issue common to diesels with egr systems (as all do now) in the formation of a hard carbon Buildup in the intake manifold down stream of the egr. It is quite possible you have such a buildup, which requires removing the manifold and hammer/chisel cleaning. No parts, just labor, but a lot of that. Or you could need a new air cleaner.

Good luck. Do get it fixed, as the air we all breathe will thank you.





Johnny G1

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Posted: 09/14/20 10:23pm Link  |  Quote  |  Print  |  Notify Moderator

Check your air filter, should not smoke if stock??


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down home

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Posted: 09/15/20 05:27am Link  |  Quote  |  Print  |  Notify Moderator

Our Cat has always done itit'saC7 and when you hit the throttle in goes more fuel.
A diesel does not mix fuel and air and go through throttle blades. It breathe in as much air as it can handle all the time. Hit the throttle and lot more fuel and black smoke. Newer diesels don't have the response of the old because emissions dictated tuning. The Volvo engines are a good/worse example. Low and slow response and power throughout the range and mileage is worse and have lots of engie fires.. Tuners spew more at take off and hot rod diesel engines rely spew the smoke as cam and injector timing is increased and more fuel is sprayed in when you hit the throttle and really gets going when the turbo(s)spool up.
When injector pumps go bad in diesels you will smell and possibly see gray smoke actually raw diesel and smell and raw diesel though the exhaust.
haven't seen in my case any MHs spewing a lot of black smoke even with a tuner.
The turbo could be getting bad...and not compressing enough air for the amount f fuel sprayed in would be the only thing I can think of at the moment.
Hard to hear in a running diesel but a stethascope on the turbo might reveal bearing problems etc. Not cheap but what s on a diesel,a Cummins Dealer or other shop hooked up to the computer, unless yours is pure mechanical diesel, can sort it out pretty quick.I don't think I want to crawl around on our engine and side radiators probably still would have to go through the bed room.A Diesel mechanic knows his brad and others real well.

dodge guy

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Posted: 09/15/20 05:44am Link  |  Quote  |  Print  |  Notify Moderator

Knowing the Cummins of that particular year. I'm thinking you have a couple injectors on their way out. As long as the air and fuel filters are fresh that's my diagnosis.

* This post was edited 09/15/20 11:27am by dodge guy *


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eHoefler

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Posted: 09/15/20 06:10am Link  |  Quote  |  Print  |  Notify Moderator

Totaly normal for a desiel of that year with no emmission equipment.


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mike brez

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Posted: 09/15/20 07:19am Link  |  Quote  |  Print  |  Notify Moderator

Just cause it smokes don’t mean it’s broke[emoticon]

[image]


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JRscooby

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Posted: 09/15/20 07:42am Link  |  Quote  |  Print  |  Notify Moderator

mike brez wrote:

Just cause it smokes don’t mean it’s broke[emoticon]


That pickup should be impounded, sold at auction to somebody that agrees to repair it before use. The owner should be fined to the point he and his family are living in a grocery cart.

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