1. Running Lean - If your car is running lean (too much air, too little fuel), the engine might be running hotter than it should. This high-temperature environment can heat the manifold to the point where it turns red hot.
2. Exhaust Leak - If you've got an exhaust leak, the heat from the exhaust gases might be heating the manifold directly, causing it to glow.
3. Vacuum Leak - A vacuum leak can cause the engine to run lean, but it could also interfere with the proper functioning of the temperature gauge. If your gauge isn't reading correctly, your engine might actually be overheating, even though your temp gauge says otherwise.
4. Bad Thermostat - If your car's thermostat is broken and has stuck closed, it could prevent coolant from flowing through the engine properly, causing it to overheat and the manifold to glow red hot.
5. Faulty Temperature Sending Unit - If the temperature sending unit is not correctly measuring the temperature of the engine, it could be showing a lower temperature to the gauge when in fact the engine is overheating.
6. Ignition Timing - Your car's ignition timing could be advanced too much, which could lead to higher engine temperatures and glowing manifolds.
7. Bad Fuel - In rare cases, substandard or contaminated fuel can create higher temperatures in the engine, and cause it to glow red hot.
To solve the problem, you'll need to pinpoint the root cause. Here's what I recommend:
1. Check the fuel pressure and oxygen levels using a fuel pressure gauge and an oxygen sensor to make sure the engine is not running lean.
2. Inspect the exhaust system for leaks using a flashlight, listening for any hissing sounds that could indicate a leak.
3. Diagnose vacuum leaks by spraying WD-40 or carburetor cleaner around vacuum lines and connections. If the idle speed increases when you spray a particular area, that's where the leak is.
4. Test the thermostat by immersing it in hot water and checking if it opens and closes at the correct temperatures.
5. Verify the temperature sending unit by comparing its reading with the actual temperature of the engine using a temperature probe.
6. Adjust the ignition timing according to the specifications of your car.
7. If the problem persists, you might need to consider using an aftermarket fuel injector kit to supply the engine with more fuel.
Remember to take all necessary safety precautions when working with hot engine parts and consult a professional mechanic if you're unsure how to proceed.
