Dear All, I am having some trouble with my 6G74. It is a over heating and the cause is unknown. If anyone has expericed the same and can guide me what to do then it would be great. The vehicle over heats when we turn on the AC..and the following steps to trouble shoot have been done.

1. Fan router has been changed (clutch fan )
2. Radiator and water passage has been cleaned
3. Thermostat valve replaced
4. Timing is perfect
5. No leakage or water shortage of any sort
6. No extra water in water bottle
7. No gas or air pressure coming in water bottle
8. No air bubbles (in radiator ) in cold start or warn engine
9. Temperature sensor changed
10. Ac compressor is not over heating
11. Alternator is given out 13.5 amps and working fine
12. Radiator cap is new 0.9bar configuration
13. Catalytic converter is clean
14. Entire exhaust is clean
15. All oils are new and upto the mark
16. Got the ac checked and as per the tech it's fine
17. Harmonic balancer is fine
18. None of the pullies have issue
19. CO2 test conducted came out negative
20. Pressurised each spark plug area to see any leakages in radiator water . Came out neagtive
21. All hydraulic tappets are fine
22. AC low pressure at 45 and high pressure at 170
23. No AC compressor heating


We are out of ideas , the only thing remains is to check the head and there are no signs which lead to a leak gasket or any head related issue.

Would appreciate your help. Thanks..