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Black exhaust deposits

snowboundrmk

By snowboundrmk
in Troubleshooting & Recalls

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snowboundrmk Enthusiast

snowboundrmk

Posted
Posted

2014 Silverado 5.3 80k. Wouldn’t start the other day when it was -30 F. It acted like it was flooded. Couldn’t mess with it for too long since the battery went dead(original battery). Got it going today with a jump from another truck and a lot of cranking since I think the plugs were fouled. It runs great now, but I saw all these deposits in the snow? Is it just carbon deposits, and do you think that could have been partially what was keeping it from starting? Maybe plugged injectors?

A0CF2164-AD08-45C5-A2B7-99F044FCCC6E.jpeg

m3n00b Enthusiast

m3n00b

Posted
Posted

It was probably the flapper valve frozen shut

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snowboundrmk Enthusiast

snowboundrmk

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Good to know and yeah it was frozen shut. I tried to turn it with a big pliers, but I couldn’t get it to budge until the truck had warmed up. Same thing with a 2015 Sierra I compared it too. I thought maybe if it was froze shut that could have been what was keeping it from running, but once it was warmed up and able to move it stayed in the same spot as when it was frozen. So it’s default position must still allow adequate exhaust flow. I left that detail out since I think that rules that out for what was keeping it from starting, unless I’m wrong. 

Sierra Dan Senior Enthusiast

Sierra Dan

Posted
Posted

After 4-5 years and 80k there will no doubt be carbon buildup just about everywhere.

Especially on the valves and in the exhaust system.

These DI engines spit out "normal" black soot on cold startup.

Could have been your flapper valve frozen. This is a common issue in sub zero temps.

m3n00b Enthusiast

m3n00b

Posted
Posted
Good to know and yeah it was frozen shut. I tried to turn it with a big pliers, but I couldn’t get it to budge until the truck had warmed up. Same thing with a 2015 Sierra I compared it too. I thought maybe if it was froze shut that could have been what was keeping it from running, but once it was warmed up and able to move it stayed in the same spot as when it was frozen. So it’s default position must still allow adequate exhaust flow. I left that detail out since I think that rules that out for what was keeping it from starting, unless I’m wrong. 

Yeah but if there was ice blocking the default passages in the closed flapper position the truck wouldn't have started. Water is a byproduct of combustion.

 

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snowboundrmk Enthusiast

snowboundrmk

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Yeah I suppose that ice could have obstructed it. By the pictures of the flapper I can find online it looks like it wouldn’t take much. I’ll have to see if my scope can reach in there so I can see how it looks for the heck of it. Otherwise I see people put a clamp on it so it stays open all the time.

I’ll look into doing something for the carbon buildup like seafoam. I’ve always seen mixed reviews on seafoam for stuff in general, so I’ll do a little research first.

SS502 Senior Enthusiast

SS502

Posted
Posted
8 hours ago, snowboundrmk said:

Yeah I suppose that ice could have obstructed it. By the pictures of the flapper I can find online it looks like it wouldn’t take much. I’ll have to see if my scope can reach in there so I can see how it looks for the heck of it. Otherwise I see people put a clamp on it so it stays open all the time.

I’ll look into doing something for the carbon buildup like seafoam. I’ve always seen mixed reviews on seafoam for stuff in general, so I’ll do a little research first.

Hey, if you’re gonna dog out the scope, think you could take a look at your intake valves? Would love to see (if you have a way to capture a picture...some don’t) what your DI valves look like at 80K miles without a catch can...or for that matter if you do run one see how they look under that scenario.

snowboundrmk Enthusiast

snowboundrmk

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I didn’t have any luck with the scope. I need to buy a better one one of theses days. It wouldn’t focus at all. I couldn’t get it past the resonator, and in the intake it was too blurry, but it did seem really crudy inside. The camera kept getting covered with crud. 

SS502 Senior Enthusiast

SS502

Posted
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22 hours ago, snowboundrmk said:

I didn’t have any luck with the scope. I need to buy a better one one of theses days. It wouldn’t focus at all. I couldn’t get it past the resonator, and in the intake it was too blurry, but it did seem really crudy inside. The camera kept getting covered with crud. 

Well thank you for trying! Have a feeling with the crud you aren’t running a catch can?

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