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Doug_E_'s avatar
Doug_E_
Explorer
May 21, 2013

Looking for a diesel guru

I had just filled up our mh with 70 gallons of fuel, from the Pilot truck stop in Madera CA.
I Drove to Stockton, with my daughter's in-laws following in their mh. When we arrived, I was told the mh was blowing black smoke, (more than usual) but only when we went up overpasses, all the way to our destination. I had not noticed any black smoke, nor had had I noticed any appreciable difference in performance, or fuel mileage. The MH ran good as always on the trip home
Just in case, I changed the fuel filters this morning, and cut the old filters apart, I saw nothing inside like allege, or any dirt.
I'm wondering if I should take the mh into Cummins West and have them check it out, or just wait and see what will happen, the next trip out.
As a side note, the wind was probably blowing @ 8 - 10 mph of head wind, and pulling a 24 ft. enclosed race trailer weighing 6000 lbs.
Class A

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  • mike_brez's avatar
    mike_brez
    Explorer
    May 21, 2013
    Black smoke is just un burnt fuel. If you were pulling a heavy load up a grade until the turbo spools up to get enough air to burn all the fuel i could see it smoke. I would also look to see if all your turbo boots are nice and tight. My little 7.3 in my pickup can smoke like a freight train.
  • Dog_Trainer's avatar
    Dog_Trainer
    Explorer
    May 21, 2013
    Black smoke could be a sign of over fueling. The injectors not needing all the fuel they are getting and the excess going out the back end. This may cause high EGTs but to my knowledge it is not caused by high EGT's. It sounds like a fueling problem but not bad enough to show in the MPG. Clogged air filter is a good check so go to the back and look at the filter indicator and see if it is in the yellow or red area.
  • 352's avatar
    352
    Explorer
    May 21, 2013
    EGT = Exhaust Gas Temperature. The higher the temp the more black smoke and the hotter the turbo and then the repairs begin. Something is overheating.
  • Mandalay_Parr's avatar
    Mandalay_Parr
    Explorer
    May 21, 2013
    Doug E. wrote:
    I was under the impression that the turbo either worked or didn't.
    If I'm wrong then maybe this could be the problem.
    By the way, I should have included that this an '05 Monaco Dipolmat with a 400 hp 8.9 cummins engine and a 6 speed Allison transmission.
    The mh has about 44000 miles.


    There is some sort of a turbo controller, a waste gate valve, so that it maintains the proper pressure.
  • The_Texan's avatar
    The_Texan
    Explorer
    May 21, 2013
    How long since you checked the air filter? Also, if the exhaust brake was sticking in a semi closed position, that will cause black smoke.
  • Doug_E_'s avatar
    Doug_E_
    Explorer
    May 21, 2013
    I was under the impression that the turbo either worked or didn't.
    If I'm wrong then maybe this could be the problem.
    By the way, I should have included that this an '05 Monaco Dipolmat with a 400 hp 8.9 cummins engine and a 6 speed Allison transmission.
    The mh has about 44000 miles.

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