smoking diesel exhaust

[dogvetia]

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

[Mr_Mark1]

Down home.... from personal experience I don't believe the power of the Volvo engine is inadequate. Certainly a fire can happen as there are a lot of components that could fail as with any coach. Newer Prevosts have a built-in fire suppression system in the engine compartment with a warning and controller at the driver area.

The Volvo engine has 500 hp with 1,750 lb. ft of torque, not too shabby! The Detroit Diesel has 515-525 hp with 1,650 lb. ft. of torque.

You cannot upgrade the engine in a Prevost. There is not enough room for a larger engine.

Sounds like 'fire-side' chat.

Safe travels,
Mark

[down_home]

We've seen three newer Prevost passenger coaches with engine fires, I don't know the years of the coaches but were newer. That doesn't mean much.
However at a Michigan RV Resort last year or year before, We sat and talked with some Folks in two Prevost coach conversions and another brand, I don't remember. One was a Marathon Coach and another brand Conversation, was about the weak take off the 515 hp Volvo and response down the road. The 650 hp, I think, Cummins engines was being requested by some of the new Customers, plus reports of fires. It was mentioned it was probably the pollution control systems now required on everything.

[Mr_Mark1]

down home wrote:
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.

"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.."

Having a Volvo engine I have never heard of what you have stated. Engine fires?
We have amazing power at 56,000 lbs. I have not heard anything negative at the Prevost centers about the Volvo engine. Did I misunderstand your post?

Safe travels,
Mark

[wolfe10]

Lots of good "what to check" posts here. Many of them FREE to anyone who cares to check.

Checking air flow and fuel filters is NOT rocket science.

[joelc]

The guy is asking a legitimate question and wants to solve a problem. No need to penalize him. I am sure many of you have asked questions before that are common sense to others, but not you. Give they fellow RVer a break.

[JRscooby]

warrenjo46 wrote:

JRscooby wrote:

mike brez wrote:
Just cause it smokes don’t mean it’s broke:B

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.

I could not agree more. How come do diesel pickup drivers think they can delete their engines and ignore the laws the rest of us should obey.

wolfe10 wrote:


And, a lot of over-fueling is done on purpose for those who want more HP and aren't concerned what they/others breath.

When I first started hauling a old hand told me "Put on what you want to haul, but never go over unless you can step with it" Back then you where much more likely to get caught with a overload if you where the slowest truck. We would put more fuel until we would get a light smoke WFO and under load. Heavy smoke, like in the pic, the engine was lugging.
The drive by wire engines don't need to put out heavy smoke,

[warrenjo46]

JRscooby wrote:

mike brez wrote:
Just cause it smokes don’t mean it’s broke:B

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.

I could not agree more. How come do diesel pickup drivers think they can delete their engines and ignore the laws the rest of us should obey.

[wolfe10]

joelc wrote:
Looked up black smoke from diesel on internet and results said over-fueling. Fuel injector wear. Check it out on the net for your model.

Sure. OR, "under airing". Either/both lead to an over-rich mixture.

And, a lot of over-fueling is done on purpose for those who want more HP and aren't concerned what they/others breath.

[joelc]

Looked up black smoke from diesel on internet and results said over-fueling. Fuel injector wear. Check it out on the net for your model.

[JRscooby]

mike brez wrote:
Just cause it smokes don’t mean it’s broke:B

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.

[mike_brez]

Just cause it smokes don’t mean it’s broke:B

[eHoefler]

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

[dodge_guy]

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.

[down_home]

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.