loosing coolant

[Hammerhead]

(11-14-2016 )milkman4282015 Wrote:  Thanks guys for all the info! I checked everything that yall sugested except testing under load. I fololowed that truck one day across I88 and it seemed to blow alot of blueish white smoke for quite a long time and i asked driver if it did this alot. Oh ya it does it quite a bit, like its going through a regen. after that i talked to a few more knowlegable mechs and they sugested to change egr cooler so thats my project for this week. keeping my fingers crossed this is it!!

Rather than crossing you fingers;
-Pressurize the cooling system (rad)
-remove the two 10mm bolts at the back of the EGR cooler
-use a light and a mirror to look into the back of the cooler for evidence of coolant leak
-if Yes change EGR cooler
-if No, remove exhaust pipe behind the doser and check for coolant
-if Yes, change doser NOT EGR cooler!
-if No, you haven't found the source yet

If you can't make the EGR cooler or doser leak while the rad is pressurized they are not likely your problem. If it appears to be "burning" the coolant and these are not the source of the coolant, you may have;
-head gasket issue
-cracked head
-injector cup leaking coolant into combustion chamber
-injector O-ring leaking coolant into combustion chamber
-liner starting to drop allowing coolant into combustion chamber

I agree that the EGR is the most likely culprit, but it is by no means the only possibility. Changing parts until a problem is solved is the biggest reason we fix our own trucks, too many of us have paid these "technitions" too much money to do exactly that instead of actually diagnosing the problem properly in the first place. I followed that logic for far too long, and Cummins never did find my problem...until AFTER the warranty has expired! Then "Oh, look at that. A manufacturing defect made the head leak coolant into the intake side of the head behind the ECM cooling plate." If they would have (or me) pressurized the cooling system for a longer time period and actually properly eliminated components with good inspections, they should have found it. As soon as the cooling plate was removed, the staining was obvious.

Rawze's instructions in post 4 are more in depth than this.