Owner Keeps Replacing Thermostat on Engine that Reads `Hot’

November 28, 2009/Steve Tackett

MOTOR MATTERS ASK THE AUTO DOCTOR BY JUNIOR DAMATO

Dear Doctor: I have a 2004 Chevrolet Impala with a problem temperature gauge. Last year the gauge went to “Hot” so I changed the thermostat, but this past spring it went to “Hot” again. I have changed the thermostat twice since the spring, as well as the radiator cap and sending unit. The gauge is “Hot” once again. When I opened the bleeder valves at the thermostat housing and water pump, air and bubbles came out. What happened? George
Dear George: Burping and/or bleeding a cooling system is a common practice on a lot of vehicles. On some vehicles we have to raise the front of the car up to 3 feet to help get the air out of the cooling system. On other vehicles, however, filling the cooling system from the top radiator hose is the way to go. We also have vacuum bleeding tools to remove air. You may want to check the cooling system for hydrocarbon in the system. A faulty cylinder head or head gasket can also cause the multiple cooling system problems you are having.
Dear Doctor: I own a 2006 Mini Cooper. At speeds above 60 mph, the engine stays at 4,000 rpm and the engine seems to be straining to shift. What can I ask the dealer to check for? While I’m there, I would like them to look into why the car has a metallic rattle at 10 mph that disappears after accelerating. Mini tells me this is normal. I would appreciate whatever you can suggest. Marie
Dear Marie: You are not alone with harsh, hard and long shifting with the Mini. The dealer may be able to re-program the computer. You could also get a second opinion from an independent shop. The metallic sound could be from a loose exhaust-to-engine mount movement. Exhaust heat shields are a common cause of your complaint.
Dear Doctor: I own a 1999 Dodge Ram 1500 with 5.9L engine and 122,000 miles. For about a year the ABS light and parking brake light have been on. I tried the scan tool and it couldn’t locate a problem. The mechanic said I only have conventional brakes now and it’s not worth fixing. I have a newborn and would really like the ABS working properly. Mike
Dear Mike: When checking a computer for anything other than a “check engine” light fault code number a vehicle-specific test must be done.

The vehicle identification number must be entered into the scan tool. Next scan down to the system that needs to be tested. This is the only way to find the fault code. A very common fault on your truck is the rear speed sensor located on the top of the rear end differential.
Dear Doctor: I brought my 2007 Saturn Aura in for inspection at 22,600 miles. The mechanic reported the engine light won’t go off and they need about a week to analyze the problem. Is this true? They said I should have both the front and back brakes replaced with calipers and rotors. It won’t pass inspection unless this work is done. The car has been running great. I can’t understand this at all. Thank you. Bill
Dear Bill: The emission system has a warranty for 5 years/50,000 miles, and on some covered parts that has to be fixed at no charge at the dealer. As for a week to find the problem, I would be out of business if I said that to a customer. A 60-second scan of the computer will give them a fault code and the system that caused the “check engine” light to come on.
Dear Doctor: I own a 2003 Chevrolet Impala. I am having a problem between the remote controls and the door locks. They work intermittently. I took the car to a locksmith who ran every test imaginable. They found nothing wrong with the remote controls and the inside door locks. I was told there is no communication between the remote and door locks. Can you help? Joyce
Dear Joyce: The system needs to be tested with a GM Tech 2 scan tool or equivalent. I have seen the same faults many times and the most common failure is the actual remote key fob unit. There may also be a re-programming update available. Sometimes you can get an aftermarket remote from a car radio shop. If you have a remote starter installed, it comes with 2 new remotes. — by Junior Damato, Motor Matters

Junior Damato is an ASE-certified Master Technician.

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Mail questions to: Auto Doctor, 3 Court Circle, Lakeville, MA 02347

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Copyright, Motor Matters, 2009