Taking the plunge. My journey as an O/O.

Discussion in 'Ask An Owner Operator' started by Farmerbob1, Jan 7, 2019.

  1. Midwest Trucker

    Midwest Trucker Road Train Member

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    Yeah you dodged a bullet man. As soon as my units bought used or new go off warranty they are coming off the road. The last two weeks I had to put a truck on the road that’s for sale and off warranty vs renting a truck. It’s been a great truck while I’ve had it but I was nervous as hell not gonna lie. Like you just found... just a matter of s couple hundred miles can mean 5 figures.

    It’s sad but I totally agree trucks are being built to run 500k miles. 300k trouble free and 500k before stuff starts hitting the fan. Even STUPID stuff like coolant main lines rusting through.
     
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  3. Farmerbob1

    Farmerbob1 Road Train Member

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    Even when under no load, a fast idle will maintain a higher exhaust system temperature than a slow idle.

    At idle, exhaust leaving the engine is almost always the same temperature, but the more exhaust volume there is leaving the engine, the hotter the components of the exhaust system will get. When you go under load, and feed more fuel in, and add in the turbo to pack air into the combustion chambers, you get even hotter exhaust and more volume.

    Your engine cooling water temperature is pretty much working by the same thermodynamic principles. You know when/how your coolant system will get hot. DEF exhaust system components will get hot under the same conditions.

    Most chemical reactions occur more easily when they have more heat in the environment. NOx reduction is a chemical reaction that benefits from higher heat.

    If you run a truck hard and get that DEF system good and hot, it will burn off some of the impurities. If you run it at an idle long enough, impurities will build up to the point where they cannot be cleaned away without a full regen, and even a full regen won't do a perfect cleaning.

    A good example of something similar might be self-cleaning ovens.

    If you cook in a self-cleaning oven a lot, especially greasy/wet foods, it will build up residue.

    If you use the broiler a lot, it will carbonize a lot of the gunk buildup, but it still eventually requires a real cleaning, which can normally be done by locking the oven door, and turning the broiler on to a higher than normal temperature (cleaning) for a while.

    But, after a lot of cooking, chances are good that you will eventually have to break down and do more than a self-cleaning. Little bits of stubborn grime will slowly accumulate until elbow grease and/or caustic chemicals will be necessary.

    All this info comes from me extrapolating what I know of physics and chemistry with what I have read about diesel NOx emission control systems.

    If anyone sees logic flaws in what I wrote, bounce them off me, please.
     
  4. spyder7723

    spyder7723 Road Train Member

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    From my understanding its about operating temperature. At idle or under low load the engine doesn't work hard so the exhaust temperature is to low to provide a proper burn and the dpf gets plugged up from all the soot and unburnt fuel sent out the exhaust.

    I've never had a truck with a dpf so won't swear by this but it makes sense, just look at the pyro guage on an engine at idle vs one running at 50% or better load. At idle my n14 barely registers enough to read, 150 maybe 200 degrees. With a light load it stays down under 400 degrees. Stick a 46k lb coil on the deck and its up around 750 and will climb to 1100 when I'm getting on it going up a big hill.
     
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  5. Farmerbob1

    Farmerbob1 Road Train Member

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    Where does a pyro gauge read data from? Next to the engine or in the stacks?
     
  6. spyder7723

    spyder7723 Road Train Member

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    Factory location is in the engine pipe about 8 inches behind the turbo. I have seen some performance engine builders put them in the manifold. From my understanding the temp will drop 200 to 300 degrees by the time it gets through the turbo. For a race team trying to squeeze every bit of hp out of an engine with hundreds of thousands invested in the engine that can be important. But for the rest of us the factory location is just fine.

    Fun trivia: many airplane engines measure it at the combustion chamber or immediately after. I got to play with a new Garmin avionics panel package back in 02 or 03 and it would show the internal temp of each individual chamber.
     
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  7. TallJoe

    TallJoe Road Train Member

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    Yes. The Cummins guy said that the very real regen is indeed occurring only when an engine is under a sufficient load (enough weight or long enough uphill climbing) as exhaust temps are only then high enough and that even parked regen cannot as effectively produce that. Problems with clogging sure start in a harsh Winter when you leave the truck idling for more than a day or two. Maybe this would be partially solved, if they made it possible to program ECMs to put trucks into regen automatically when unattended, otherwise only a block heater or APU could solve the problem.
     
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  8. Farmerbob1

    Farmerbob1 Road Train Member

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    Well, ran from Flagstaff, AZ, to Amarillo, TX today. Fuel economy looks good still.

    Stopped in Flagstaff at 6.8 mpg.

    After overnight opti-idle fuel use, 6.6 mpg.

    After arrival in Amarillo, was at 7 mph.

    Now I get to sit on my ### until Tuesday afternoon to wait for this receiver to open. Fuel econ will tank.

    However, i am quite happy with the results of recent maintenance on my fuel economy.

    Just curious though. Hub bearings. Is there a recommended replacement time frame even if there is no clear issue with them? I spent some time as a steel mill mechanic, and thinking about how much weight is on truck bearings, and how much rotation they go through, I'm a bit worried about what might be going on inside the hubs.
     
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  9. Rideandrepair

    Rideandrepair Road Train Member

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    Now that’s frugal!!! Good for you. $$$$ in your pocket where it belongs. Not supporting everyone else’s businesses.
     
  10. spyder7723

    spyder7723 Road Train Member

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    I wouldn't call it frugal. More like well maintained. I spend money without batting an eye when it needs spent to fix something that needs fixed. My maintenance costs are kept very low because i am under it greasing it and looking for problems to catch them before they get a chance to grow expensive.
     
  11. Rideandrepair

    Rideandrepair Road Train Member

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    That gives me an idea. Why not bake the filter clean in a self cleaning oven? While the wife’s not around ofcourse.
     
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