Cooled EGR and engine wear

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47
Location
Colorado
I'm curious if EGR contributes significantly to cylinder and ring wear, particularly in diesel engines. I know soot is abrasive and CI-4+ oil is formulated to keep the 'extra' soot from EGR in suspension. But what about the soot that comes directly into the combustion chambers from EGR? It seems reasonable to assume this unfiltered soot will, over time, cause significant additional wear. I'd appreciate hearing your thoughts on this. Thanks, -john
 

JHZR2

Staff member
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45,945
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New Jersey
Given that there are thousands of early 1980s Mercedes diesels on the road, many still running like new, with EGR for all that time... even before oil was formulated to accept the soot... and with an average fleet mileage of probably about 250k miles... Id say not to worry about it. Soot is a function of atomization, combustion quality, and to some extent, the polyaromatics and similar in a fuel. Gassers never had to worry much about soot, most of what it produces can be considered super fines anyway. EGR has been used for years in gas engines... lots of them have lasted too. EGR fouling and plugging seems to be the biggest issue on gassers and diesels. IMO the biggest issue with EGR is the effect on the oil... so using a well formulated oil to combat its effects is the smart move, and I wouldnt worry about it much from there... Lots of durability has been exhibited in well maintaned engines running EGR. JMH
 

Kestas

Staff member
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13,942
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The Motor City
Why do you think soot is abrasive? And even if it was abrasive, why would oil be formulated to keep soot in suspension where it can do more damage? I don't think there's anything to worry about. The EGR can contribute to deposits, but not abrasive damage.
 
Messages
4,378
Location
Camas, WA
Soot increases wear when it gets to certain levels. It's preferred to keep it solution instead of sludging out who knows where. The Cummins diesel in my truck is an 'evil CA emmissions' engine, which has been designed to run cooler to in order to reduce nitrogen based pollution. As a consequence it generates more soot and has a 3750 mile severe duty oil change interval instead of the 7500 mile interval found on '48 state trucks'. The upsaide is that running cooler it evidently has the potential to be longer lasting.
 

JHZR2

Staff member
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45,945
Location
New Jersey
quote:
Originally posted by Kestas: Why do you think soot is abrasive? And even if it was abrasive, why would oil be formulated to keep soot in suspension where it can do more damage?
Because the results of implementing a filtration system to readily (i.e. not a bypass filter) remove such small particles would be a very tough thing to do. oil does suspend soot... there is no other choice. Daimler found years ago that wer rises exponentially above 2% loading in the oil... now whether that was just because of the dispersant packages available back then, or if, even say delvac 1 with >4% soot loading capacity starts to accelerate wear at 2%... I dont know. JMH
 
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