Exhaust

[Dale Ennis]

Not sure if this is a problem but it took me by surprise. Parked out by the wood pile in the snow, left the truck idling.
My exhaust melted a hole in the snow,I would expect to see black soot, but just pee yellow coloring to the melted snow.
Am I having combustion or fuel delivery issues?

 

[AnonEd]

I'm just guessing out loud here and hoping others have better answers or sahre your experience. My truck makes no noticeable soot idling, but I've only done that in snow once it was already warmed up. Since your truck got warm enough to melt snow it was presumably warm enough to make condensation in the pipe. Based only on what I've read, condensation reacts with some materials used in some exhausts, and the results can turn snow yellow.

 

[Vaughn MacKenzie]

What AnonEd says makes sense, it can also partially be a small amount of soot. Even when it's not visible to the naked eye there is a small amount of particulate matter coming out the tailpipe.

 

[Dale Ennis]

Thanks for the input guys.This thing has 320000 on it and runs super smooth and strong. I was just surprised on the coloration.

 

[BigPapa]

If the engine was cold, it could be fuel. This is why we're told not to idle a cold engine. Cylinder temps are not high enough to burn all the fuel resulting in "cylinder wash" from the unburnt fuel. I know on my 12-valve my EGT's will run @ 250* at idle until it's up to operating temperature, or even after warmup if left idling long enough and it's cold enough outside.

 

[Dale Ennis]

If the engine was cold, it could be fuel. This is why we're told not to idle a cold engine. Cylinder temps are not high enough to burn all the fuel resulting in "cylinder wash" from the unburnt fuel. I know on my 12-valve my EGT's will run @ 250* at idle until it's up to operating temperature, or even after warmup if left idling long enough and it's cold enough outside.

I was unaware of the idling a cold engine thing. I’m a cummins noob. It was 30 ish degrees and the engine was probably not at prime op temperature.I’ll keep a closer eye on that.