DEF Smoke while driving

doser

Member
driving a friends 07 mack. While driving smoke comes from under cab. This happened twice this week .got stopped ,could not find problem. Is this the regen system ?
 
Could be late 07 or early 08. Gots regen switch. On dash. I failed to say ,when I stopped the regen light was on ,for few seconds.
 
DEF was not until the EPA10 trucks which would have been 2011.

EPA07 trucks do have a DPF though. So you are mainly referencing the regen for that.
 
It would be an indicator to me that there is an exhaust leak or the DPF is burning WAY too hot. So yes, I'd get it looked at.
 
It's going in Saturday ,I'm told. As far as parked regen it seems,to ldle up at times. I suppose it doing idle regen. Thanks for help.
 
Does it have a weed burner exhaust? Sometimes the dose goes to hell and dumps way to much fuel for a regeneration and you blow smoke out the exhaust pipe.
 
Always kind of amuses me when I meet a megafleet truck on a grade and they's puffing white smoke like one of those old steam locomotives. :D

The Mack I drive started having "issues" a couple months back with the regen system. Mack put a new "module" in it and re-set it. Has done a forced "Parked Regen" twice.... smoke rolling out from under it like it was on fire. But now it does an "auto regen" every time I stop for 10 min or so and will keep doing that every half hour or so. We have to keep the truck idling to keep heat on the load and the only way I can stop the continuous regen is to idle the truck with the trans in gear. :dunno:

Same old story.... govt mandated super new tech and nobody knows how to fix it.:stare2:
 
It's just a normal DPF system doing a regen. The smoke comes from below because it's a grass burner.
 
Not a grass burner. What southern fried said ,sounds about right.
If it's not a grass burner but it's smoking from underneath, something is definitely wrong.

Do not idle it while sleeping.
 
Had the same problem. Random moments of smoke coming out from behind me from underneath. Thought it was DEF too.

Turned out to be a small oil leak hitting the exhaust. It was on the very back of the block couldn't see it unless you were pretty much behind the tire with a flashlight.

Worth a look though if you haven't already. Or just take your fingers and poke around trying to find leaks.

It was on a 2012 cascadia though. DD13.
 

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