Cylinder condition, thoughts?

diesel_importer

diesel_importer

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Truck came in blowing coolant from puke bottle. Already deleted, but still had EGR cooler. I verified the cooler wasn't the culprit (yet to see a Cummins EGR cooler be the culprit of cooling system pressuring up).
This truck would bubble all the coolant out at idle, engine cold. After getting the head off, I was surprised to see the cylinder walls in this shape. 135k miles, can't feel the marks with your finger nail, but cross hatch is gone in those areas.
What are your thoughts?


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I've seen several say thanks EPA The EGR is the culprit here! It puts blow by and exhaust back in the cylinders which crystalizes and scores the cylinders! Way to go most 6.7's won't see 200k! This one got hot for sure is that metal at the top off the pistons?
 
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I assume that's the same cylinder shot from two directions?

Looks like the early onset of four corner scoring. I would agree with others, it's been hot enough for the Rings to butt.

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That engine most definitely had blowby. :)

I've pulled a bunch of these apart and if it's marking the cylinders, it's usually into the piston skirts as well.
I'd say the engine was hot temp wise, not just an EGR fault.

At any rate, you're looking at more than a "hone and go" job there.

Mark.
 
Most likely doesn't have a lot of blow by from the looks of it, we've seen them here in worse shape with hardly any blowby, but noticeable top end knock. I would be willing to bet the skirts are scuffed as well and its well on its way to bigger problems. I would recommend a rebuild while the block can still be salvaged at .020".
 
Mark Nixon said:
That engine most definitely had blowby. :)

I've pulled a bunch of these apart and if it's marking the cylinders, it's usually into the piston skirts as well.
I'd say the engine was hot temp wise, not just an EGR fault.

At any rate, you're looking at more than a "hone and go" job there.

Mark.
Click to expand...

What is wrong with honing? I am just curious/learning...
 
Sometimes honing a damaged cylinder just isn't enough.
If you hone to clean up deep scratches, then you can end up with too loose of piston-wall clearance, causing piston "slap" and cause damage that way.
Then there is still the potential for scratches or defects to cause blowby.

Some builders precision hone cylinders to make more clearance in high performance applications, this is so that under heavy loads and higher RPMS, when the pistons "grow" with the more intense heat, it helps keep the pistons from scoring the bores.
A downside is that it, again, increases piston "slap" when cold and/or idling.

Honing to fix notable cylinder defects isn't the same as honing for clearance.

Mark.
 
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