Even after installing a remanufactured head and 2 hole head gasket. I believe it's leaking somewhere near the head gasket in the back. When I did the rear main seal I didn't see and signs of a cracking. Even have the egr delete so there's no hoses going back there anymore. Not sure how to go about it now without taking the motor out. Any suggestions?

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I'm beginning to think cavitation of the cylinder sleeve because this time there's oil in the coolant.

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usually oil in coolant , is oil cooler . but leaking coolant again after cylinder head was done , maybe liner protrusion is a problem , back in my days of wrenching , CAT 3406 engine use to do that , liner protrusion issues. international DT466 engine was bad developing pin hole thru liner mid way do to cavitation , bad coolant , so yes it is possibility that you have similar issue

I'm going to clean up the motor re check the egr block off plate and go from there. Put dye in it and see if I can 100% find where it's coming from.

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Is there a way to test to see if that's the problem without having to get into the motor? Before we replaced the the head we did a pressure test and it held but once it was driven down the road for 5 or 10 minutes it was leaking coolant and oil. When that happened it looked like straight coolant.

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well since you don't see the coolant on overflow , so no compression is present in cooling system , then yes you should put dye in it and pressure test to pin point that external leak .