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Discussion Starter · #1 ·
Can a few of you folks chime in to help me understand the EGR in my truck. The new EGR was just installed by the dealer, per the recall. I understand the basic concept that the exhaust gases are introduced into the intake to reduce emissions.

1. I understand that there is a valve in the EGR. When is that valve open and when is it closed? What conditions in the engine cause the EGR to change and adjust?

2. I have read that a symptom of a bad EGR is declining coolant levels in the over-flow tank. What does the coolant system have to do with the EGR and where is coolant going if the EGR is failing?

3. I understand that earlier Green Diesel Engineering tunes turned off the EGR. Is this true? What does the GDE tune do to the EGR?

Thanks in advance for the education!


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1. The short answer is engine load. There's a bunch of complicated logic in the ECM that controls it based on engine load, operating temp, etc. Our ECM contains about 6-8 engine operating modes if I recall and each has it's own EGR command table for control in that operating mode.

2. The short answer is into the intake and burned in the engine. There's two things that flow through the EGR system: Coolant and Exhaust Gases. The exhaust gases are controlled by the valve you reference. The coolant is not. But either way exhaust gas temps can rise up to 1500* F (hence the need for coolant to cool the gases before they re-enter the engine) which means the cooler is subjected to huge heat cycles and temperature swings. Most likely these temperature cycles result in fatigue, which causes coolant to be introduced where the exhaust gases flow through.

3. Tunes that turn of the EGR prevent the exhaust gases control from opening and therefore the gases no longer flow into the engine. BUT coolant continues to flow through the EGR cooler. This is why some folks end up having to delete the EGR because they fail anyway. But the number of EGR coolers that fail on tuned trucks are very small.
 

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The best EGR is a deleted EGR.
Mine was removed due to a leaking EGR cooler three years ago. When I removed the intake tube I was shocked to see the caked on soot inside the intake just after one year from new.
Since the delete my oil stays clean for the duration of its 10k km life between changes. Not introducing these abrasive soots into the engine can only be a positive factor in your engines longevity.
 

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The biggest thing that controls egr flow is the upstream Nox sensor that is the sole purpose of egr. The egr is flowing some basically all the time just with various amounts. There is also a bypass valve before the egr cooler which opens to allow exhaust gasses throw a different path where they dont get cooled, fire starter. The electric valve after the cooler controls the actual flow as well as the egr flow control valve between the intake manifold and cold side intercooler pipe. The vgt also is used to help increase the pressure delta to create flow as well.
 

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Discussion Starter · #5 ·
Regarding an EGR failure.... Is there any way coolant can get into the oil sump?


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Regarding an EGR failure.... Is there any way coolant can get into the oil sump?


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Coolant would be introduced into the intake manifold and ingested into the engine combustion.
I think the only way it could make it into the oil would be if large amounts of coolant were introduced and some passes by the piston rings or due to a head gasket issue from engine overheating due to low coolant.
 

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When my truck hit 100,000 miles, I deleted mine. GDE tuned it off at 5,000 miles. My diffuser tube was still quite clean. My 2 cents would be to get a tune that at least shuts it off, or better delete . Many will disagree, but my tail pipes are still shiny, intake manifold is clean, as is MAP sensor. If it's gone, no worries about soot or antifreeze or truck catching fire. Wonder how much air pollution generated when one burns to the ground?
 

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Discussion Starter · #8 ·
Well.... So here's the deal. On Monday the dealership did the EGR work. On Friday I changed the oil and I noticed two things....

1. The Coolant Level was down about an inch.
2. The last bit of oil that drained out of the sump, looked a little like the dreaded milkshake.

I am very concerned I have coolant leaking into the oil sump.


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Top up your coolant and mark the level when the truck is absolutely cold like first thing each morning. The low level could be from an air pocket that has worked its way out now. Wait for about a 1000 miles and take an oil sample and send it to Blackstone et al for an oil analysis.
 

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Discussion Starter · #10 ·
Top up your coolant and mark the level when the truck is absolutely cold like first thing each morning. The low level could be from an air pocket that has worked its way out now. Wait for about a 1000 miles and take an oil sample and send it to Blackstone et al for an oil analysis.
Yes Sir.. I did that and will be watching the level very, very closely.
 

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Top up your coolant and mark the level when the truck is absolutely cold like first thing each morning. The low level could be from an air pocket that has worked its way out now. Wait for about a 1000 miles and take an oil sample and send it to Blackstone et al for an oil analysis.
I marked mine at its lowest point refiled then marked again. This way i can see if i loose any and if it goes past the lowest point which it hasn,t
 

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Discussion Starter · #12 ·
Top up your coolant and mark the level when the truck is absolutely cold like first thing each morning. The low level could be from an air pocket that has worked its way out now. Wait for about a 1000 miles and take an oil sample and send it to Blackstone et al for an oil analysis.

Did that...... and after weeks..... nothing lower......

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When my truck hit 100,000 miles, I deleted mine. GDE tuned it off at 5,000 miles. My diffuser tube was still quite clean. My 2 cents would be to get a tune that at least shuts it off, or better delete . Many will disagree, but my tail pipes are still shiny, intake manifold is clean, as is MAP sensor. If it's gone, no worries about soot or antifreeze or truck catching fire. Wonder how much air pollution generated when one burns to the ground?
Just curious if all of the GDE tunes turn off the EGR? I also put GDE on my truck at about 3-5k miles. I was thinking it did but that's been quote awhile. If I go in for the EGR replacement, I assume the tech's would also mess with the controller. Is this correct? I'm really at a loss as to what direction to take on mine.
 
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