Answer: You may have an radiator that is partially plugged. Replace radiator with new to repair problem.

Question: 2002 Lexus RX 330 mileage: 65,000. I am completely stumped on this problem. It's going on a year now, and neither I nor any mechanics have been able to resolve it. The engine overheats when the thermostat is installed. When the thermostat is removed, it holds a normal temperature. When it overheats, the scalding water comes out of the small hose leading to the water reservoir. So, the radiator cap is relieving the interior section and permitting the hot water to escape. What is causing this? There, that's all the question I have. But let me explain what I've done to try to eliminate the problem. 1. Have already bought three thermostats. 2. Have installed the thermostats with the spring assembly toward the engine, and the rubber seal on the circumference of the thermostat. 3. Have bought three different radiator caps (one was actually defective). All caps are made for Lexus with a 16-psi relief pressure. 4. Had radiator removed and manually cleaned by professional radiator shop. 5. Replaced the two main hoses to and from radiator. 6. When checked with pressure gauge on radiator water fill section, there are no leaks in the system. 7. Water does not leak from the system. 8. Temperature sensor on thermostat housing has been checked and is working fine. When temperature increases, hydraulic fan is increased in speed and blows like crazy. 9. Short circuited hydraulic fan sensor to keep fan activated at full speed when system was full of water. Driving car lasted about 5 minutes until engine completely overheated into red zone. 10. Strangely enough, I placed the thermostat in the engine last night, and other than a slight overheating of the system for about 20 seconds, I was able to drive the car for over an hour with no apparent over temperature condition. The next morning, however, I checked the water and it was low. Took about 2 quarts to fill. This may have been due to not completely filling the system the night before. 11. Checked both thermostats today in hot water on the stove. Both opened at about 190C so I'm guessing that they both work. They are both new. 12. If I drive the car without a thermostat, I never have an overheating problem, nor does the car lose water. 13. A new water pump was installed last year. 14. New belts were installed last year. What are some possible things to check to resolve this mystery? Is there anything in the engine section where the thermostat housing is attached, which is mechanical and can be damaged? As you can see, I'm at a loss for a solution to this problem. No one has been able to resolve it, and it's now over one year. This car was not well cared for in the past and my mechanic changed the pistons, rings, bearings and seals in the motor, along with the water pump. Valves were cleaned and the heads milled slightly for flatness. This car apparently had this problem before I bought it. Someone has installed an electric fan with silicone sealant on the a/c radiator. We've disconnected the fan, but can't get it off due to the bonding of the silicone. While I would like to think that this has something to do with the engine overheating, I know it doesn't. It's just an eyesore and something that will eventually be removed. So, if you are the genie with the magic solution, please, please let me know! Hoping that you guys are better at solving this than the mechanics down here.

Answer: You have a leaky head gasket problem or a cracked head. Disassemble to replace head gasket of cylinder head with new, reassemble to recheck system.

Question: 2002 Dodge Ram 3500 mileage: 47,000. I just bought this truck from an older couple it looked great and ran great. Until my seventeen year old son overheated it. When we bought it, the guy said that there was a leak in the cooling system that he could not find. Well I found it! It is coming from the head gasket into the # 1 cylinder. No antifreeze has gotten in the oil so do you think that just changing the head gasket will solve the problem? Any help or tips would be great.

Answer:   In addition to replacing the head gasket, we would recommend resurfacing the cylinder head and checking it for cracks.

Question: 2001 Ford Focus mileage: 110,000. I'm having a problem with the electric cooling fan. The fan will not come on which causes the car to run hot. The fan motor works when straight wired to the battery. It also works if I remove the wire from the electric fan switch and ground it. During troubleshooting I have replaced the electric fan switch, the a/c-cooling fan module and air temperature sensor. This is why I replaced the fan switch. Also note that the a/c compressor does not kick in, unless I jumper it at the accumulator press switch. When this is done the compressor kicks in and the electric fan kicks in, remove the jumper and compressor kicks out (like it should) and the fan runs for a few seconds (like it should) before cutting off. Also note the code scanner does not give any trouble codes. It all checks out fine. What have I missed? I have spent numerous hours troubleshooting and looking at wiring diagrams, with very small print, I'm stumped!

Answer:   It sounds like you have temperature sensor that is operating out of range. Replace the temperature sensor to repair the problem.

Question: 1999 Toyota Camry mileage: 90,000.  Hi Guys, My daughter just made a trip to California from New York to start a new job.  Had timing belt, catalytic converter, belts, antifreeze (flush and change), new air filter, new spark plugs, all changed.  The car ran great until she got to the mountains.  Overheated every time she started to go up the mountain.  She is now in Sequoia National Forest and can't get her car up to her campground because it over heats on the road up the mountain.  Traveling from around 3000 ft. to 7000 ft in elevation.  Any idea what could be going on with it?  It runs great until she starts up the mountain roads.  No overheating until then.  She's on her own out there and need some advice as to where to start to have someone trouble shoots it for you.  Running the heater full blast did seem to help at times, but is not helping now. Thanks for any advice you can give us.

Answer: A partially plugged radiator may be causing your problem.  Replace the radiator with new to repair problem.

Question: 2002 Dodge Caravan mileage: 76,000.  My cooling fan keeps going out.  First time dealer said the module was faulty, probably getting too much amperage and blew the fan.  I bought a used fan, it lasted 4 months until it went out.  I can't find another used fan.  This makes me think this a common problem and what is the likely cause?

Answer:   Your best bet is to replace it with a new fan motor assembly.

Question: 1999 Jeep Cherokee mileage: 128,000.  This thing will not stop overheating. I have put a new head, head gasket, water holding tank, oil change, flushed twice, new thermostat housing and new thermostat five times, two different new radiators, new hoses and a tune-up.   I am at my wits end and I have had help from everyone.  Can you please shed some light on this problem for me? Thank you.

Answer: Check the cooling system clutch fan, if there is any sign of leakage the fan clutch has failed and need to be replaced to repair problem.

Question:  2002 Chevy S-10 Pick Up mileage: 53,000.  Recently have started overheating, checked fluid levels (ok), and pulled radiator cap, no movement of water and top return hose was limp.  Replaced thermostat & gasket.  Replenished fluids, let run with cap off (trying to get rid of air) worked ok for about two weeks, then started overheating and no heat/defrost.  Rechecked fluid levels cold engine radiator and overflow all were fine.  Highway driving for a week no problems.  Then 35 to 50 mph, started overheating, reservoir was low, replenished, highway speed for 45 miles, temp up and down, now overheated as pulling off highway and low speed driving.  Fluid levels still ok.  Unable to figure out what’s happening.  Overheated in Olympia.

Answer: Check the cooling system clutch fan, if there is any sign of leakage the fan clutch has failed and need to be replaced to repair problem.

Question: 2002 Chrysler Sebring mileage: 55,000.  Car has been overheating twice at separate stations the head gasket has been repaired.  The overheating fan relay was replaced.  The antifreeze still leaks from the radiator cap eventually the car will overheat again.  Water pump, thermostat gaskets have been replaced.  What could cause the pressure build up and how would the mechanic repair?  Cap is new.  Thank you I am presently stuck out of town.

Answer: A partially plugged radiator may be causing your problem.  Replace the radiator with new to repair problem.

Question: 2003 Ford Taurus mileage: 70,000.  I have an overheating problem caused by the coolant overflowing the top of the coolant expansion tank.  I have replaced the radiator cap, the thermostat, the temperature-sensing switch and the water pump.  The radiator fan is electric and runs when the coolant temperature gets to 215 degrees and switches off at 210 degrees.  The running time of the fan is very short (about 20 seconds).  When the car is parked, the cooling system seems to be operating properly.  I can see the coolant level in the expansion tank go back into the system when the fan comes on.  But after about 15 to 20 minutes of driving the coolant starts overflowing the expansion tank.  This problem seems to have started after the water pump went out and the car overheated.  The problem occurs mostly in cold weather because when we run the A/C the radiator fan runs constantly.  It seems to me that the radiator fan is not running long enough.

Answer: A partially plugged radiator may be causing your problem.  Replace the radiator with new to repair problem.

Question: 1999 Honda Accord mileage: 97,000.  My car is been over heating and I've replaced the radiator, radiator cap. For 2 weeks, it ran fine but it soon started up again.  It gets hot suddenly, rapidly.  I have also flushed the radiator twice.  Could you please give me an explanation or how to fix it?

Answer:   Your thermostat sounds like it is malfunctioning. Replace thermostat with new to recheck system.

Question: 2002 Buick Park Avenue mileage: 51,000.  I've been having trouble with my car overheating.  The engine light ONLY comes on while using the heater/defrost (NOT when we use the A/C though).  A year ago, I replaced the Water pump and thermostat (and its housing).  Now the Heater refuses to work all the time.  It did start to work after adding coolant and water, but the car still overheated.  Any suggestions?

Answer: Your radiator may be low on water causing it to overheat.  Coolant may be lost through a water pump or it could be that the radiator is plugged which causes overheating resulting in the lose of coolant.

Question: 2002 Infinity G20 mileage: 64,000.  Hey guys, need your help. I have been stiffed for $700.00 bucks.  The engine has been running hot; temperature gauge on hot, blowing cool air.  First it was "running low on oil; tightened drain plug.  Week later same problem: then my so-called mechanic installed a thermostat.  Couple of days later; same problem: this time "needed" a new radiator cause it was leaking antifreeze.  Two days later same problem.  This time they want to stiff me for 1350.00 for a "head gasket”, Can't anyone, tell me what is wrong with it?  Need a second opinion.  HELP!

Answer:   If your car is losing coolant, which causes it to run hot, it must be determined where the coolant leak is.   It may be an external leak (coolant hoses, water pump, etc.)  Once determining the problem, repair as needed to recheck system.