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Topic: Cummins 5.9 smoking (Read 642 times) previous topic - next topic

Cummins 5.9 smoking

My Cummins 5.9 in my '93 U225 has started smoking a lot under dul throttle. I noticed about 250 miles ago returning to Tucson. My tail pipe is now completely black. Oil, air filter , etc. changed about 7000 miles ago just before heading out on a long trip.

Could this be air filter, turbo, other? Thoughts?

Roger Worley
1993 U225 36'
Build #4295
1979 Int'l Scout II
2005 BMW R1200RT

Re: Cummins 5.9 smoking

Reply #1 –
Turbo, turbo piping lose leaking, charge air cooler cracked?
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Cummins 5.9 smoking

Reply #2 –
Could be an air issue. Have you been on a lot of dirt roads lately?
 More  knowledgeable people will be chiming in soon.
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: Cummins 5.9 smoking

Reply #3 –
Agree with Bruce.

Start with the easy stuff.

Verifying that you have enough AIR.  So, air filter OK, plumbing to and from CAC OK, exhaust manifold to head not leaking, manifold to turbo not leaking.

What does the fuel in your primary fuel filter look like?

Any change in oil level or oil viscosity?

I am sure others with more Cummins B experience will chime in.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Cummins 5.9 smoking

Reply #4 –
What color smoke?
Keith
2003 U320 38' #6197

Re: Cummins 5.9 smoking

Reply #6 –
Black smoke and soot is not enough air, so you are either loosing boost, or you have an intake restriction. You can make a boost leak tester with a pvc pipe cap that fits in the intake hose and put an air fitting in the cap. Get a pressure regulator or just turn down the pressure on a compressor and put 10-20 lbs in it, then listen for leaks or spray some soapy water on the connections.
1991 U300 Side Aisle 6V92 Silver #3897
2004 U320 40' #6246

Re: Cummins 5.9 smoking

Reply #7 –
Could also be one or more bad injectors or an engine problem.
Dennis Haynes
Bohemia NY
2008 Nimbus 342 SE Carlyle
Build #6475
Motorcade #19148

Re: Cummins 5.9 smoking

Reply #8 –
A failed injector is usually accompanied by a lost cyl power. Does the engine skip at idle ?

Re: Cummins 5.9 smoking

Reply #9 –
Still need to know the color of the smoke.  Then, also need to know which fuel pump you have.  VE rotary pump or P-7100 inline pump.  '94 was the first year of the P pump in the Dodge pickups.  Before that were VE pumps.  Need to determine which one you have.

VE Pump Versus P-Pump: Inside The Most Popular 4BT and 6BT Cummins Injection...
Keith
2003 U320 38' #6197

Re: Cummins 5.9 smoking

Reply #10 –
Smoke is black; tail pipe is black with soot. Engine idles smoothly.
1993 U225 36'
Build #4295
1979 Int'l Scout II
2005 BMW R1200RT

Re: Cummins 5.9 smoking

Reply #11 –
Black smoke, soot, is more fuel than you have air for.  So loss of combustion air supply some where in the incoming air lines, air filter, CAC, tubing joints and turbo.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Cummins 5.9 smoking

Reply #12 –
Yes
Check for intake restrictions. At idle , no boost. So the leaky pipes won't show up. 

Re: Cummins 5.9 smoking

Reply #13 –
Fuel pump is the inline pump; six separate outlets on the top.
1993 U225 36'
Build #4295
1979 Int'l Scout II
2005 BMW R1200RT

Re: Cummins 5.9 smoking

Reply #14 –
As mentioned, black smoke means fuel without enough air/boost.  Boost leak most likely.  Start with the easy stuff...look at the hoses between the turbo outlet and CAC piping, at the CAC and into the intake.  Look for any signs of a hole or loose clamp(s).

Take the intake hose off the turbo and look at the compressor wheel.  Give it a spin with your fingers.  Does it look undamaged and spin freely?
Keith
2003 U320 38' #6197

Re: Cummins 5.9 smoking

Reply #15 –
Diesel is clear; maybe slightly green/yellowish.
1993 U225 36'
Build #4295
1979 Int'l Scout II
2005 BMW R1200RT

Re: Cummins 5.9 smoking

Reply #16 –
Checked air cleaner; has about 7000 miles on it; looks like new.

Disconnected the turbo inlet; turbo turns freely.

All hose/tubing seems tight; no breaks/cracks found.

Engine oil level is a little low

Have not tried to pressurize the system yet.
1993 U225 36'
Build #4295
1979 Int'l Scout II
2005 BMW R1200RT