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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3304
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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I have a dt466 that has excessive to dark smoke and runs

Customer Question

I have a dt466 that has excessive white to dark gray smoke and runs rough and it seems like fuel in oil as it washes dipstick. Am I right in thinking a o ring on injector or what else could it be. The dark gray smoke after it runs for 30 seconds throws me off.
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Pete replied 1 year ago.

Hi my name is ***** ***** I will be happy to help with this today.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know.

The gray smoke will come from thinned out oil due to fuel in the oil that will make it past the oil rings on the piston from being thin and can smoke like this here.I have seen this occur before.

The most common cause I have seen is usually one or more of the fuel injectors leaking down fuel or sticking open allowing way to much fuel into a cylinder.This causes the smoke issue as well as the fuel in the engine oil.It is possible this is an injector O ring fault but in most cases I find on most models one or more injectors needing replaced.

You are correct on running it to long as the thinned out oil will damage the engine in some cases and the over fuel can actually break a piston as I have seen with hot pistons with cold or excess fuel hitting it.In turn the piston will then damage the cylinder wall and destroy the engine completely.

I would have the injectors tested (on some this may require a special fuel adapter to test injector fuel pressure drop to find one at fault) to locate any at fault needing replaced.The injectors may also need to be visibly inspected to locate any that may be leaking or an o ring fault with one or more of them.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete.

Expert:  Jeremy replied 1 year ago.

My name is ***** ***** I will assist you. Thank you for requesting me.

The issue isn't going to be piston rings on this engine. It will end up being one of the injectors being cracked and/or injector seals.

Remove the ICP, put shop air there and you will hear air on the rail. This is to confirm that you have a seal issue at minimum.

Remove the injectors and get them pop tested. This will confirm which ones are leaking.

You didn't post the year of your DT466 so if it is a early DT, it may just be the seals. If a newer DT, it may be seals and injectors. Either way, be ready to do the seals.

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Expert:  Jeremy replied 1 year ago.

Did you need anymore assistance with this? I'm following up since the question is still showing as open/unresolved. Thanks.

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