EGR.......

If the EGR valve and cooler is bad, then you need to replace them with new valve and cooler.

 

Have you check oil cooler ??? I had similar symphtoms and it was bad oil cooler

 

EGR cooler had developed a crack. Soot into coolant and coolant loss is common telltale symptoms.

Time to replace EGR cooler ASAP before your destroy your after treatment system.

Doing the EGR valve also is a good idea while you're in there. Expect a somewhat healthy Bill.

The cause;

EGR cooler tries to take 400-1000° F exhaust gas and cool it down with 180-220° coolant. It flows through a little radiator..

The "EGR cooler"..... Problem is there is constant expansion and contraction from heating up and cooling down.....

Hairline cracks start to develop and the pressurized coolant pushes into the intake of motor at low or no boost conditions. .....

Under higher boost conditions(turbo 15+ psi) the high pressure exhaust gas gets pushed through the crack into the cooling system which is a lower pressure.....(coolant 12-16psi)

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