Check for bubbles in the radiator. First off, it's important to realize that what you found is discolored by your antifreeze mixture so don't rely on what color it is or isn't until you fully flush the remnants of all antifreeze from your system and retest. Check with engine cold and again with engine warm. The exhaust gases that escape into the water jacket will be choke full of hydro carbons. They appear slimy and will coat the internals of the water jacket. The coat of slime reduces your engines ability to shed heat both thru the block/cast and thru the rad as it more or less insulates the internal surfaces. -It can be very difficult to clean out after the problem is fixed I have flushed some engines a dozen or more times using just water and different types of rad flush. None of them completely cleaned it out but for the most part, the water eventually stays clean. . One thing you have not shown us is the rad cap. Take the truck for a good drive so that it is defiantly up to steaming hot (185+) The rad cap, whether pressurized or not will allow a certain amount of air/steam past it into the rad over flow tube. If you manage to get the engine decently hot, or even close to boiling, much of the pressure and steam will be forced past the seals of the rad cap and a brownish gunk will ac***ulate at the rad cap. Many times it will look like a melted aero bar in that it will show tiny bubbles in the good. I have picks here of a system I just dealt with. Which was one with a head gasket leak. I will post pics of what the drained Clean water looked like as well as what was found on the 4 lb pressure cap. ... .
. Pics below Your pics shows gunk mixed with antifreeze and therefor your findings are a different color and consistency. This is what a head gasket leak does to the rad cap and Clean, well flushed system with just water in it. . I had drained the system and fully flushed the remaining antifreeze with both the engine running, the pet**** open and the hose trickling into the top of the rad for a good 1/2 hour to flush all antifreeze out before I took the pics. I then went for a 50 mile cruise in which the water pumps agitated the internals of the water jackets, and the temp came fully up. That is what I found. The clean water with the rad full at first showed signs of bubbles which lead me to believe the engine had a head gasket problem. Once the head gasket was fixed, I ran straight water to ensure I wasn't going to waste expensive antifreeze, and also so that I could flush the system 1/2 dozen more times. I used several different brands of rad flush. Each time I simply poured the can in to the radiator as instructed and went for another agitating cruise. It took some time but the water eventually cleaned up to the point that I felt the snot was cleaned from the water jackets and rad. The rad cap eventually cleaned itself up as gunk came out of the system. That stuff is like a wool blanket and doesn't allow heat to transfer out of your rad, it will prevent your engine from shedding heat. Hence I flushed many times until the system became clean. I saved a jug of the hot brown water and it settled almost clear over night. The stuff at the bottom of the bottle was fine rust/sand/dirt and remnants of bars leak from days gone by. Hot water, well agitated: Settled rust/dirt/bars leak: Settled cold water: .
Wow, thats some nasty ****! I checked mine today for air bubbles and found none. My radiator cap is still clean and the anti freeze is green yet. I'll give it a flush and see what happens. Thanks for the pics.
The Jalopy Journal
