What Causes the Engine Exhaust Pipe to Turn Red?
3 Answers
Engine exhaust pipe turning red is caused by: 1. Some of the gas in the cylinder entering the exhaust pipe and continuing to burn; 2. Overly lean air-fuel mixture, where the combustible gas burns slowly after ignition, delaying combustion until the exhaust stroke; 3. Burning gases rushing into the exhaust pipe, raising the exhaust temperature; 4. Poor sealing of the exhaust valve or excessively small valve clearance, causing combustion gases to enter the exhaust pipe and raise its temperature; 5. Overly delayed fuel injection timing. The functions of the exhaust pipe are: 1. To reduce vibration and noise; 2. To extend the lifespan of the exhaust muffler system. Maintenance methods for the exhaust pipe include: 1. Avoid prolonged high-speed driving with the choke closed; 2. Avoid installing windshields or decorative items in front of the engine and muffler; 3. Minimize prolonged high-revving of the engine while stationary.
With decades of experience in car repair, I've found that a glowing red exhaust pipe is usually due to engine combustion issues. The most likely cause is an imbalance in the air-fuel mixture – either too much air and too little fuel leading to slow combustion and rising temperatures, or too much fuel and too little air resulting in incomplete combustion and heat buildup. Ignition system failures, such as weak spark plugs or aging coils, can also cause misfires or delayed ignition, increasing exhaust temperatures. A clogged catalytic converter is even more common, where trapped exhaust gases cause heat buildup and redden the pipe. I recall an old car whose exhaust glowed red after a long uphill climb – it turned out the catalytic converter was completely blocked and needed replacement. Regular checks of the fuel system and exhaust components are essential to avoid overheating risks that could lead to fires, especially during high-speed driving.
Last month, my modified car also experienced a red-hot exhaust pipe. After troubleshooting, I found it was due to incorrect air-fuel ratio tuning. After the modification, the intake and exhaust flow increased but weren't properly matched, leading to reduced combustion efficiency and concentrated heat. Alternatively, during the catalytic converter modification, the incorrect size caused exhaust gas retention, heating up the pipes until they turned red. It's essential to regularly monitor exhaust temperature using sensors—don't just chase performance while neglecting safety. During maintenance, check the throttle body and fuel injector conditions to control the mixture ratio. High temperatures can damage exhaust system materials, accelerating aging, so timely cooling measures are necessary.
