Been having an overheating problem lately. The 6.2 has always run at 190 like it should. 4 weeks ago I went muddin. Hit a very deep hole "up to door handles in water". Coated the radiator with the mud, mud dried and the motor over-heated, caught it at 230, shut it down. Pulled radiator cleaned all the mud out. It now stay at 190 at idle and when driving on the road, like normal. But out on the trail at slowwer speeds it starts to over heat. Hit a mud hole last weekend, was reved close to full trottle for about 30 second and the temp shot for 190 to 260 real quik. Going to pull the t-stat and run it and see if it is the problem. If not I will swap the fan clutch and hope. I have no water in the oil and no water coming out the exhaust, so I don't think it is a head gasket or a cracked head. What else could it be? After I figure it out I am pulling the diesel and swaping in a 350 /forums/images/graemlins/yikes.gif need better wheel speed.