B-series Cummins cylinders at 448k miles

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A_Harman

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My Dodge is in the shop for a head gasket change, which turned into a cylinder head swap.
Since they are waiting for parts, I took the opportunity to take pictures of the cylinders.



Cylinder 1 closeup.


Cylinder 1 overall.






Overall pretty good, but cylinders 1 and 6 didn't have any crosshatch left that I could see.
Cylinders 2 to 5 still had a good amount of crosshatch.
 
Wonder what the difference is... you'd think that being end cylinders they would run a little cooler, and therefore maintain a little bit more piston clearance. Still, not bad for nearly half a million miles! Thanks for the pics!
 
lighting can play a big role in seeing crosshatch in a photo, but even to the naked eye you couldn't see any on 1 and 6?

Could always drop the pan and pull those cylinders for a stone or stiff arbor hone, but I suppose thats up to the customer.

thanks for the pics!
 
Originally Posted By: bullwinkle
Hope they clean all the junk out of those cylinders before they put the head on! Did they find you a decent price on a new head for it?


Oh yes, they just had pulled the head, so there was debris, oil, and coolant on the piston tops.
The new cylinder head is EXPENSIVE, but comes with a lifetime warranty that will be honored anywhere in the US.
Oh, my aching credit card!
 
Originally Posted By: SOHCman
lighting can play a big role in seeing crosshatch in a photo, but even to the naked eye you couldn't see any on 1 and 6?

Could always drop the pan and pull those cylinders for a stone or stiff arbor hone, but I suppose thats up to the customer.

thanks for the pics!


I borrowed a shop light so I could get up close to the cylinders, and couldn't really see any crosshatch on 1 and 6.
I asked the shop owner about doing a flex-hone job on it, and he said the pan would have to be dropped to get the piston-rod assemblies out.
I just don't want to spend the money now. The oil consumption has been hanging around 3k miles per quart, and the fuel economy and towing power has not changed as far as I can tell, so I think it will go a bit longer.
 
Last edited:
Originally Posted By: JLTD
Thanks for the pics! OCI and oil used please?


Mostly RT6 for OCI's between 21k and 37k miles.
From '03 to '09, VPBC 15w40 annually, which in those years was ~18k miles.
I've been doing used oil analysis since 2011, which are all posted in the diesel UOA page here.
 
Originally Posted By: jhellwig
Had the head gasket let go? What is with the carbon in between cylinders?


The head gasket was leaking coolant externally at the rear corner of the block. It was going through about 1/2-gallon of coolant per day, and was really making a mess underneath the truck. But no coolant was showing up in the used oil analysis, and it was not pushing coolant out of the radiator. I am comfortable that the fire ring seal was still good on all cylinders.
 
I would definitely install new main bearings and a new oil pump. At almost 1/2 million miles, and the low RPM torque of that engine, it’s cheap insurance.
 
Use a ridge reamer (PROPERLY!) and it will clean that ring of carbon off the top of the cylinder without taking any metal off.
 
Originally Posted By: gman2304
I would definitely install new main bearings and a new oil pump. At almost 1/2 million miles, and the low RPM torque of that engine, it’s cheap insurance.


There is a LOT of merit to this....
 
Originally Posted By: gman2304
I would definitely install new main bearings and a new oil pump. At almost 1/2 million miles, and the low RPM torque of that engine, it’s cheap insurance.


That's the thing....It's NOT cheap to pull the oil pan on a Dodge Chassis.
 
Originally Posted By: rollinpete
Gotta love them hatch marks


Honing crosshatch marks are deep- often several thousandths of an inch. Maybe a 60 year old Mexican school bus wouldn't have many crosshatch marks left, but unless something is really smoked in a cylinder, I would hope that there would be crosshatch marks visible.

Don't get me wrong. Nice looking cylinders on that engine for the miles, but "seeing crosshatch marks" can be a poor way of evaluating cylinders and cylinder taper.
 
Originally Posted By: Scdevon
Originally Posted By: rollinpete
Gotta love them hatch marks


Honing crosshatch marks are deep- often several thousandths of an inch. Maybe a 60 year old Mexican school bus wouldn't have many crosshatch marks left, but unless something is really smoked in a cylinder, I would hope that there would be crosshatch marks visible.

Don't get me wrong. Nice looking cylinders on that engine for the miles, but "seeing crosshatch marks" can be a poor way of evaluating cylinders and cylinder taper.


Well, no. Hone scratches aren't several thousandths of an inch deep.
Here is a profilometer trace from a Volvo truck cylinder liner:



The deepest valley in the trace is 5.2 micrometers, which is .0052 mm, or .0002 inches, or 2-ten-thousandths of an inch.
So if there are similar crosshatch valleys in my cylinder bores, the maximum diametral bore wear to make the deepest hone marks disappear would be .0004 inches. For cylinders where about half the hone marks are gone, the wear would be about half that. Then after the hone marks completely disappear, one would no longer have the visual reference of honing scratches to estimate bore surface wear, and it would be necessary to use a dial bore gauge. The naked eye can be a good profilometer if you know how large the surface features are.
 
Originally Posted By: krismoriah72
I would have gotten a used or reman head and spent the extra on new main bearings and an oil pump.


I'm just not seeing the need to change main bearings and the oil pump. Oil analyses over the years have shown the occasional Lead spike, but never a large amount of Copper to indicate significant lining wear. And if I was going to worry about bearings in any engine, it would be the rods. There are two main bearings to carry the load that is transmitted through one rod bearing, and the rod bearings are smaller. If there is one thing that Cummins knows, it's how to design bearings for engines that make a lot of low-end torque.

Oil pressure is the same as it's always been since I bought the truck at 46k miles, and I have never noticed any pressure fluctuations. Why would I conclude that the pump needs to be replaced?
 
Originally Posted By: A_Harman
Originally Posted By: JLTD
Thanks for the pics! OCI and oil used please?


Mostly RT6 for OCI's between 21k and 37k miles.
From '03 to '09, VPBC 15w40 annually, which in those years was ~18k miles.
I've been doing used oil analysis since 2011, which are all posted in the diesel UOA page here.


'Preciate it.
 
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