Coolant in oil & EGR tune up questions

[jeff_cm870_vnl]

Hello, Thanks for letting my join! While I have been doing a lot of reading and learning, this is my first post. Sorry in advance for the long length! I have a 2003 CM870 ISX500/1650 in a 2004 Volvo VNL630. I use it to pull an RV. The truck was commercial for about 620k miles, then was converted to RV use by another family that put only 50k miles put on it in five years. I purchased it from them almost two years ago with right around 670k miles on it.

The engine had all new injectors and a top end adjustment done by Cummins at 630k miles (I have the receipts for this). No long after I got it (around 685k miles) I had the turbo replaced as the engine was starting to miss on climbs and the wastegate was leaking externally. The shop that did the turbo replacement said the EGR cooler looked very dirty. He might have even said there were signs of coolant but sadly I do not remember. Shortly after and full of naivete I installed the ug*ly f*ix thinking that simply not using the EGR would be a easy solution. After talking to a couple smarter people than myself, and reading a lot here I realized that was a bad idea for the ISX engine. So, I removed it a few days ago and reinstalled the original baro sensor.

While the EGR was deactivated, I had my first oil analysis done by BS Labs. Surprisingly, they noted that there are signs of small levels of coolant in the oil, which is a serious concern for me. Here is the lab results:


While BS said the leak is small, it has me a little spooked and I want to fix it before it gets any worse. I do have to add a few cups of coolant to the reservoir every few weeks (keep in mind how little the truck is driven vs a commercial truck). I am not sure how to proceed with identifying how the coolant is getting into the oil. The injectors have less than 100k miles on them, I suspected the EGR cooler but it was 'disabled' while this sample was accumulated, so I don't know that it could be the cause. To be sure on the EGR cooler, I am ordering the recommended cooling pressure test system and will be testing the it the way Rawze recommended in about a week. I am looking for any help or recommendations on this as I am really unsure how to find this leak and stop it before it gets worse and causes damage to the engine.

Secondly, While I have the EGR system open I plan to do the 'tune up' and replace all the sensors (as I still get a miss every once in a while and I suspect the sensors are all original). I pulled the intake temp sensor the other day and it was heavily caked with soot. I have a couple questions about the EGR tune up: Assuming the EGR cooler is OK, can I/should I try to clean it internally? Also I am curious how to clean the pipe that wraps behind the engine from the EGR cooler to the intake pipe. Do people typically clean those pieces as well?

Thanks in advance for any help, insight, or questions you can offer