John Deere 7430 Pressure in header tank

[LisaP]

57 year John Deere 7430
Got bit of pressure in the header tank and using 15 litres of water over 800 hours Of work!
Any ideas on the problem?

 

[Spanner_Man]

Head gasket / blown EGR cooler

 

[LisaP]

Is it right you can by pass either the EGR valve or the EGR cooler?
guessing if do this and still same problem then we know it’s the head gasket?

 

[Phil P]

Let the pressure out of the header tank, start the engine and let it tick over. Then see if you can feel it building pressure by squeezing the top hose. If it feels like someone is pumping it up with a bike pump the head gasket is blown.
If it doesn’t pressurise it will probably be the egr cooler split but don’t rule out the charge cooler as well. It will only pressurise under load if one of the coolers has failed.

Is it right you can by pass either the EGR valve or the EGR cooler?
guessing if do this and still same problem then we know it’s the head gasket?

derv doctor can do an egr/cooler delete for around the same price as a new egr valve.