Join Date: Jan 2003
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Re: What\'s up with my @#$^%^ heater?????
If the herater core is not covered with leaves and the temp control valve is working properly then it sounds like the heater core or a hose is plugged. The block should be clear as you stated earlier. Here's my tried & true flush technique. I do this to every water cooled engine I own. BEWARE this method will find any weak corroded part in the system and cause a leak, such as the heater core in your case. First find a source for reverse osmosis filtered water, if its been post filtered thru some deionization resins as well thats even better. Next drain the old coolant. Now refill with the RO/DI water (without any antifreeze) and drive the truck around town for about 20 miles or just run it this way for a few days as long as freezing is not a problem w/o antifreeze in the system. Inspect the hoses, core, valve unit and other parts for leaks during this time. Last step is to flush out this water, should look dirty, and refill with RO/DI water along with antifreeze. The idea is that the RO/DI water is a great solvent, it's so pure that it will dissolve the gunk in the system. Some folks use distilled water but reverse osmosis water is best since it will not have metal ions in it from the distilling process. You can buy this water at better aquarium shops because they use it in saltwater aquariums. Certain medical and / or chemical labs have the filter units to produce this water. Try "The Aquatic Critter" in Nashville if you can't find some in town. This treatment found the holes in my K5 Blazer heater core and let me know that the Zuk water pump needed to be replaced too!