I have a Mitsubishi Lancer 2002 (2.0 engine) Automatic Rally Edition 150K miles and it is overheating (3/4) only when I am in Heavy Traffic, but if I put the car in neutral and accelerate it, the Temp. Gauge drops to normal (half). Already have changed the radiator, the water pump as maintenance and also eliminate the thermostat testing. I friend of mine scanned with an OBD device and have 3 codes, P0421 (Catalitic Converter Bank 1), the P0135 (Oxygen Sensor (o2) heater circuit malfunction Bank 1, sensor 1 at front) and the P0507 (Idle Air Control System RPM Higher Than Expected). I don't know if any of those is activating the others. I'm looking for a professional advise. Thanks for your time with mi case..

 

1. Check your fans and belts. If the thermostat on the fans are faulty they may not turn on at the right time and cause a temp rise. Since you replaced your pump, I'm assuming you also changed your belts? When the A/C compressor goes on, the fans should also come on. You might want to listen for that.

2. Open your radiator cap while running the engine and see if there's any oil mixing with the radiator fluid.

3. Check your oil and see if there's any water or other liquid mixed in with your oil.

If 2, 3 or 2 and 3 are present, you might have a blown head gasket at the very least.

4. Make sure you're using a 50/50 water to coolant mix....if only water, the temperature threshold will be lower as plain water has a lower boiling point than the coolant mix.

5. Check your temperature sensor. It might not be overheating at all.

As for the other codes....Perform a full diagnostic on each part listed in the codes showing on the scanner. Just use a tester and base the tolerances on the manual. If they exceed or are below the recommended threshholds, then replace parts as necessary.

Don't take my word for it. These are just the items I would look at if I had your issues. But I don't believe you have a blown head gasket.

Good luck.

 

I'll check it by tomorrow. I got a question about the fans, when I turn the car on, are both fans are suppossed to start at the same time or not?

Thanks,
CDJ

 

Sorry I would not know since I don't have a service manual for your particular model.

What I do know is that the fans have thermostat controls that kick in when the engine reaches a certain temp. If the engine is started cold, then the fans don't go on. When you switch on the AC--meaning the AC compressor goes online, you should also see a fan come on.

I had a similar problem with an older Galant but my case is different in that I increased the piston size and thinned out the engine block to the point that it was too close to the water jackets. I solved this issue by upgrading my fan to a higher capacity model.

Good Luck.