*********************************************************** THIS IS AN AUTO-REPLY FROM TROUBLESHOOTERS.COM Your overheating-related question has been received and examined at Troubleshooters.Com, and we believe that most of your questions will be best answered by referring you to the list of diagnostic tests at http://www.troubleshooters.com/tpromag/200005/200005.htm#_strategy, after reading the cooling system on that page (http://www.troubleshooters.com/tpromag/200005/200005.htm), as well as all Troubleshooters.Com overheating material listed in large-print links at http://www.troubleshooters.com/tautomot.htm. Be sure to read the material on http://www.troubleshooters.com/toverheat.htm, paying special attention to the safety material. Please do not resent this autoreply. Troubleshooters.Com receives over 50 overheating queries per day. The vast majority are clearly answered by material already on Troubleshooters.Com. Without these autoreplies, we'd have only two choices: 1) charge money for overheating help, or 2) stop all overheating help by email. Those overheating questions not answered by existing Troubleshooters.Com materials, or clearly showing that the T.C described tests have been correctly done and interpreted, are usually answered personally by Steve Litt HELPFUL OVERHEATING HINTS ABOUT HEAD GASKETS... DO NOT continue to drive a car in an overheated condition. Overheating is the #1 cause of broken head gaskets. Head gasket replacement is difficult, time consuming, requires special tools and knowledge, and involves a huge labor charge. DO NOT continue to drive a car with steam coming out the exhaust. That indicates a broken head gasket allowing coolant into the cylinders. Continuing to drive a car in that condition can break the starter and/or flywheel, leading to several hundred dollars of additional repairs. Be aware that a broken head gasket can BE CAUSED by overheating, and that a broken head gasket can also CAUSE overheating. It's a chicken and egg sort of thing, and causation must be determined in order to fix the problem. Few things are more frustrating than to spend $1200.00 replacing your head gasket, only to have a hose-caused overheat break your new head gasket. A broken head gasket can cause cyclical overheating, first few miles overheating, or overheating, and/or coolant loss. The coolant loss can be immediate, but typically it appears during sustained high speed driving. Other cooling system flaws can also cause these symptoms. That's why upon observing, of these symptoms, you need to test for combustion gas in the coolant, which indicates a head gasket problem. Combustion gas in the coolant can be tested either with a smog sniffer or a NAPA block test. These tests are discussed in the Troubleshooters.Com materials. Be aware that a broken head gasket can allow harmful combustion gasses into the coolant WITHOUT causing any of the following three symptoms. 1. Steam or white smoke out the exhaust 2. White/yellow gunk on the oilcap 3. Coolant in the oil or oil in the coolant Therefore, a broken head gasket is NOT ruled out by the lack of all the preceding three symptoms. Be aware that over half the country's mechanics will disagree with the preceding two paragraphs, and claim there's no reason to test for combustion gas in the coolant. That's one reason why there's so much misdiagnosis in overheating problems. I personally assume the heads and head gasket are good when tests and correct observation confirm ALL the following: 1. No steam or white smoke out the exhaust 2. No white/yellow gunk on the oilcap 3. No coolant in the oil or oil in the coolant 4. No evidence of combustion gas in the coolant (NAPA block test or smog sniffer) GENERAL OVERHEATING DIAGNOSTIC TIPS... Respond to any coolant loss with a pressure test, and act accordingly. Overheating at idle or low speed but not above 30 miles per hour points an accusing finger at the fan, fan clutch, fan electronics, or fanbelt. My experience is that "stop leak" type products do more harm than good, as they often gum up components that were formerly good. My experience is that "boiling out" or "rodding out" a radiator is rarely helpful, and soon the overheating condition returns. It is my belief that when replacing a radiator, you should get the highest capacity radiator available, even if that means hiring somebody to build a huge custom 4 row. An extra $200 is a tiny price to pay for the comfort of knowing you can drive over any hill in any weather with any reasonable load, and not worry about overheating and breaking your head gasket. In all but the most obvious causes of overheating, the money spent on a pressure test and a test for combustion gas in the coolant usually saves even more money in misdiagnosis. A new water pump or thermostat will not fix an overheat caused by a broken head gasket or a leaky top hose. Steve Litt Webmaster, Troubleshooters.Com http://www.troubleshooters.com slitt@troubleshooters.com (Legal Disclaimer) Follow these suggestions at your own risk. I am not responsible for damage caused by or associated with your following of these instructions. Copyright (C) 2001 by Steve Litt, all rights reserved. ***********************************************************