Losing antifreeze

Egr cooler maybe?

 

EGR cooler definitely. Replace before it becomes a several gallon a day habit.

 

Egr cooler,my 2010 Pete I was driving did the same thing.

 

Another vote and almost certainty that it is the egr cooler

 

I second the egr cooler..

 

Probably the EGR cooler.

 

EGR cooler is an easy fix. For Cummins, however there are another nightmares. I had the same issue, so here we go:

• EGR cooler. That's a $2000.00 fix if you wrench it yourself.
• Block fretting and liner seating. This is a common nightmare to deal with, because it acts like EGR cooler or the turbo leaking, but instead it passes minuscule amounts of coolant into the combustion chamber and 1 gal / 700 miles sounds like what I had. It shows up in the oil analysis as Potassium, NOT glycol. The glycol based coolant burns up and you will notice no glycol in the oil analysis, but consistently high amounts of potassium (>100 ppm) and sodium (> 999 ppm). This failure will NOT INTRODUCE COOLANT IN THE OIL. This is one for the $130.00/ hour Cummins dudes. Never Peterbilt. ( I did end up having to machine the block, with new liners, to fix this. $$$$) This failure also has the distinction of NOT showing up in a coolant pressure test, unless the damage is already catastrophic.
• Turbo. They'll sell you a new one. But it would rather show coolant in the oil. And it only apply to VG Turbos, as far as my experience goes.
• Repair shops' favorite: A cracked head. Not all cracked heads leaks coolant though. Not all cracked heads are broken. But all Cummins heads in operation are cracked. It's their flaw. It starts within 1 hour of hard operation, at the exhaust ports, and the cracks are measurable but insignificant. The cracks does progress slowly to some unknown threshold, usually well before leaking. It's kinda important to understand when talking to the service desk. Don't go buying a new head that you didn't need in the first place.
• The head gasket. It's an easy fix, but in my humble opinion better if you get it done at the $130.00/ hour Cummins dudes...
• But as you did or didn't say: Head gasket, turbo and oil cooler failure tend to show in the oil. Which brings me to EGR and block fretting.
• Last and least, I am sure you've checked: The reservoir cap. It's easy to get this one wrong, though.

Do yourself a favor and NEVER do business with Peterbilt regarding a coolant leak. Instead save yourself a lot of headaches and go to a Cummins dealer. If you want, I can share my RO's with you so you can be better informed.