![]() ![]() Many times the head of the head bolt will be loose(like a long cross threaded bolt, it can be pushed and pulled side to side, but can't be turned by hand). At this point some combustion gases are also introduced into the cooling system which will make new coolant (dexcool or green) acidic in a hurry. The bolts are sealed from coolant, so unless your block is porous, the head bolts don't get wet with coolant until the earliest stages of head gasket failure. I respectfully disagree about acidic coolant ruining head bolts. I was almost AFRAID to start messing with it. I should know better than neglect the maintainence. The other time, had to have an alternator replaced. the AC would quit blowing thru the vents and blow thru the floor outlet. Had to have a leaking vacumn hose replaced. ![]() I did replace the battery once and put a couple of sets of tires on it. etc etcĪll I ever did to it was regular oil changes. I shouldn't admit it, but I had never changed it on the 1999 van that burned. but I will be changing it more often than I have before. The 1999 van that burned in my garage fire last year.also had the CAST IRON 4.3 V6. I wonder why GM puts it in EVERYTHING then? I believe many of the problems with the head bolts come from the coolant not being changed at the recommended interval and the coolant becoming acidic. The only thing I know is that every time that I open my cooling system (the last time at 98K miles) the dexcool coolant looks brand new, so go figure. Many of the purge/bleed lines are clogged with sealer that owners use when they begin experiencing overheating and coolant loss. The moral of the story is to not use dexcool in cast iron engines. The rust inhibitors are not needed in aluminum applications as aluminum does not rust. It was not designed for cast iron applications as it does not have or NEED rust inhibitors, once air gets into a cast iron system oxidation/rust occurs and that is your sludge. It is my understanding the dexcool will sludge if it is used in cast iron applications. Not trying to be a smart a55, but that is why I use green coolant in my vehicles, including the ones that came with dexcool. I've never seen green coolant sludge like dexcool. I've been an ASE certified tech for 14 years and worked at GM dealers for the last 9. Come to think of it, this is the kind of gunk that plugs the bypass tube on N*'s, air locks and overheats engine which I'm sure is of no help to already weak threads and overstretched head bolts. ![]() Not uncommon to replace radiator, heater core, t-stat and radiator cap along with removing block drains, chisel gunk out so that the drain is open, chemically treat and back flush engine for hours. The biggest coolant catastrophes I've seen involve dexcool with air in the system(a small leak causes system to run low for extended period of time because ignorant owner doesn't check fluid levels on a regular basis). Torque to yield bolts and weak threads in the block blow head gaskets. Green coolant didn't cause head gasket failures. It is also good for 5 years/100,000 miles vs. DexCool does not have silicates in it so water pump seals, etc will last longer due to the absence of the abrasive silicates. Why anyone would install green coolant in a system that came from the factory with DexCool is beyond me. If you then switch back to Dex, the silicates will deplete the corrosion inhibitor package in the DexCool so you will need to change the DexCool every two years. Once green coolant is introduced into the cooling system, it will plate the internals with silicates. If you switch to green, you will need to change it every two years. I recommend you keep running DexCool in your car. DexCool was not introduced until the '96 model year. A '93 Northstar had green coolant from the factory. ![]()
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