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Cat C7 white smoke

kamilski

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I've had my truck for a couple of years. Usually after idle when I would start to drive it it would give me quite a lot of white smoke on a first 2-3 take offs from stand still.
Lately I have noticed the truck has a bit of a struggle getting off the line and also when going lets say in a 3rd gear at steady 1700rpm seems like it'll cut off and turn on one of the cylinders while blowing white smoke.
Higher speeds runs perfectly fine. No lack of power etc etc.
I recently have replaced 1 of the injectors that failed. My mechanic told me someone who fixed the truck before had couple wires from one of other injector harnesses sliced and connected so I should look into replacing the whole harness.
Do you guys think that could be causing the problem?! Lately the temperatures outside have dropped significantly and I wonder if that has something to do with it???
Any ideas on what else I should look into as a quick fix ?!

Thanks for all the help in advance
 

davekc

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I've had my truck for a couple of years. Usually after idle when I would start to drive it it would give me quite a lot of white smoke on a first 2-3 take offs from stand still.
Lately I have noticed the truck has a bit of a struggle getting off the line and also when going lets say in a 3rd gear at steady 1700rpm seems like it'll cut off and turn on one of the cylinders while blowing white smoke.
Higher speeds runs perfectly fine. No lack of power etc etc.
I recently have replaced 1 of the injectors that failed. My mechanic told me someone who fixed the truck before had couple wires from one of other injector harnesses sliced and connected so I should look into replacing the whole harness.
Do you guys think that could be causing the problem?! Lately the temperatures outside have dropped significantly and I wonder if that has something to do with it???
Any ideas on what else I should look into as a quick fix ?!

Thanks for all the help in advance

Not really. I would probably replace the harness. The connection can become weak over time. A cat will usually throw a code if it is the harness. Probably also want to check to make sure you don't have a cracked cup/injector sleeve since you are getting white smoke. Especially if it is doing it when it is warmed up.
Always replace that sleeve when they replace the injector. New injector into a old sleeve doubles the chance of it cracking.
Check your anti freeze for residual deisel on top in the resevoir. Kind of look likes a black/brown ring on top of your fluid.
Good luck!
 

purgoose10

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I would also ad to what Dave said. Get your oil analyzed to see if there is Antifreeze in your oil. Cats will have trace amounts but look for significant increases. Also a head gasket will do that with a minor crack or break than when it heats up it expands closing the break and no white smoke.

Also go to Cat and get them to pressure test it. That will tell you if it's a gasket.
 
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VTurri

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Check for oil in the fuel too. C7's go through injectors. The just had to replace all 6 in an owner op truck. We sent the injectors out for testing and they were all bad.
 

kamilski

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Not really. I would probably replace the harness. The connection can become weak over time. A cat will usually throw a code if it is the harness. Probably also want to check to make sure you don't have a cracked cup/injector sleeve since you are getting white smoke. Especially if it is doing it when it is warmed up.
Always replace that sleeve when they replace the injector. New injector into a old sleeve doubles the chance of it cracking.
Check your anti freeze for residual deisel on top in the resevoir. Kind of look likes a black/brown ring on top of your fluid.
Good luck!

Ive had all the sleeves replaced 2 years ago. It's happened to me before when one of them was leaking and i got diesel in the antifreeze. Not the case here. Thanks tho
 

davekc

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Ive had all the sleeves replaced 2 years ago. It's happened to me before when one of them was leaking and i got diesel in the antifreeze. Not the case here. Thanks tho

Is it throwing any kind of code? That would indicate a harness problem.
 

davekc

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nope. Nothing at all

Then you likely can eliminate the harness since that is electrical. It won't pick up a bad injector, sleeve, or issue with the pump.
A fuel pressure test and a cut out should give you your answers.
 
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kamilski

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Thats actually not true. I had a check engine and a code 4 weeks ago when an injector failed in cylinder 2
 

davekc

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Thats actually not true. I had a check engine and a code 4 weeks ago when an injector failed in cylinder 2

True.....but the guy told you to replace the harness. Thus.....it is electrical if it threw a code.
If the pressure is extremely off at the injector, then it could throw a code but it would have to significantly change the fuel pressure at the pump which isn't too likely. But is a distant possiblity.
 
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EASYTRADER

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White smoke is generally coolant related, so start there. If you haven't been using any coolant. The second thing is glow plugs, white smoke can also be un burned fuel.

Based on your description of symtoms those are the 2 likeliest causes.
 
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davekc

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White smoke is generally coolant related, so start there. If you haven't been using any coolant. The second thing is glow plugs, white smoke can also be un burned fuel.

Based on your description of symtoms those are the 2 likeliest causes.


White smoke is a possible indication of burnt anti-freeze. Also condensation. In his case, the cat doesn't have glow plugs. It uses a heated intake
 

kamilski

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The reason I was leaning towards un burnt fuel is because of the harness my mechanic mentioned to me. I am going to start from there along with replacing thermostats because it's been running a bit cold
 

BobWolf

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Sounds like an injector or fuel problem especially if you replaced one injector in the past year. Typically the rule is if you replace one replace them all as if one goes the others usually follow one or two at a time.
I sent you a P.M.

Bob Wolf.
 

Bruno

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Cats are known for the High Pressure Fuel Sensors going bad. The white smoke after idling is from not having the RPM's turned up to 10 to 12 on the tachometer. When Idling you need to have the RPM's turn up to get enough oil up to the head. The smoke you see is from the oil getting up to the head and burning which causes white smoke. I bet your truck runs hotter and the fan kicks on more because you don't have the idle turn up. The white smoke when your in third gear sound like the High Pressure Fuel Sensor. We have had this happen a few times with some of trucks with Cat Motors. When this happens in third gear I bet your truck seems like it has a miss.
 

davekc

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Could be a sensor but I don't believe he is getting a code. A bad sensor should through a code.
 

Bruno

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Could be a sensor but I don't believe he is getting a code. A bad sensor should through a code.

Our trucks wouldn't throw a code most of the time when it did this Dave. Why I don't know. I just know the high pressure fuel sensor was the cause every time.
 

RETIDEPXE

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Might want to check the inlet air heater. "The air inlet heater improves the engine's ability to start when the engine is cold. The air inlet heater also reduces WHITE SMOKE when the engine is cold." Quoted from a blog found here; ENGINES FOR HEAVY EQUIPMENT & MORE: C7 and C9 Engines for Caterpillar Built Machines/ Air Inlet Heater Circuit - Test

This blog is hard to navigate and I have not figured out how the search feature works, but, when you have time, scroll toward the bottom of the page and there is a wealth of info on the C7/C9 there.

Let us know what you find.
 

kamilski

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Thanks guys for all the help. I'm taking my truck to my mechanic today and we will see what he says.
As to my truck running hot....it doesn't. I actually got the thermostats because it has been running unusually cool, and cools down quicker than it used to.
I will keep you posted
 
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