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Clunk that Stumps the Car Experts I read your section in the Lynn Haven Ledger and have a question that, so far, has stumped the car "experts". I have a 2003 Buick Century four door. Every few months I experience the following. I stop for a stop sign or signal and when I start off again it is like someone hit the car from the rear. Usually it is enough that I feel like I was hit by someone going 10 or 15 mph. It may happen once on a given day and then nothing for several weeks or months. It seems to definitely be in the rear but with front wheel drive the only thing I know of in the rear is the rear axle, differential, brakes, gas tank ??? If it happened every time I stop maybe the problem could be more easily isolated. Any ideas? Jesse B. Lynn Haven Florida I don’t know who the “car experts” were that you have talked to. So I decided to look for a TSB for clunk or bang from rear of vehicle. Sure enough, there is one dated August 2005 bulletin # 04-06-04-066A. It affects 2003-04 Buick Century, Chevy Impala, Monte Carlo, and Pontiac Gran Prix. The article states that customers may complain about clunk/bang type noise when a vehicle comes to a stop or during parking lot maneuvers, when the fuel tank is ½ to full of gasoline. The noise is due to fuel sloshing in the fuel tank and a broken baffle in the fuel tank. The correction is to replace the fuel tank with P/N 15141578 and re-program the computer to keep from setting a check engine light with an emissions code. This is why it is so important for car owners like you, to find repair shops that have computer databases for information. I have several information sources I use such as Alldatapro, Napafix and iATN.net. With this type of information today’s auto repair shops can get help to problems that used to take hours and sometimes days to figure out. So when you have a car problem with your vehicle find a repair shop that has access to this information. It will save you money and time, in this busy world we live in, time is money! Live long and prosper. James, I have two questions, the first is for my 5.7 liter TBI engine, I just replaced the radiator, water pump with belts and new hoses. I also replaced the thermostat. I believe the thermostat rated for this vehicle is a 195 degree. I put in a 180 degree thermostat and the engine still seems to be heating up more than I would like. Would I be hurting anything by going to a 160 degree thermostat on that vehicle? Secondly, The A/C is not working and I believe the compressor seals have popped. I don’t really want to go to the new R134 system since I will have to replace the entire system which will be very expensive. Do you think there would be any chance of anyone being able to help me get my existing system going? Thanks for any ideas you have, Scott B.

Automotive engineers who get paid to “tear up” engines in the laboratory tell me they can destroy an engine quicker by running it at 160 degrees. This is due to the engine not getting hot enough to evaporate the acids in the crankcase. Your trucks engine requires 195 degree thermostat, nothing cooler. Your trucks electronics are calibrated for the engine to run at this temperature. Besides effecting fuel mileage you are promoting premature transmission failure because the transmission won’t go into overdrive until it is around 185 degrees. Running a too cool thermostat will contribute to “crankcase sludge” in your engine. This will cause your trucks engine to smoke and use oil prematurely. This is why older cars engines of the 1960’s and 70's wore out and smoked by the time they had 100,000 miles. Running the engines too cool with inferior oil by today’s standards. So if you think you have an overheating problem you need to make sure that it is not a head gasket problem. To verify the truck can cool down when it is hot, just take a water hose to the radiator while the truck is running. If the temperature gauge goes down then you have a problem with the fan or radiator. If it still gets hotter and won’t cool down then you have a head gasket (or cracked head) or the wrong water pump (turning backwards) As to the A/C system keeping R-12 as the refrigerant is the smart thing to do in the long run. R-12 may cost more than R-134a. In the long run it will do a better job keeping you cool and you’re a/c system lasting longer. Live long and prosper.

 

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