24V Glow Plug Caterpillar 3304 3306 3406 Replaces 3T-8706 4N-0360

This listing is for a 24V glow plug. Do not install a 12V glow plug in a 24V system (or vice-versa). If you’re unsure, check the machine electrical system or confirm the part number you’re replacing.

It replaces Caterpillar 3T-8706 and 4N-0360 / 4N0360. If your old plug matches one of these numbers, this is the correct cross-reference.

The thread size is 3/8"-24. Always start threads by hand to avoid cross-threading.

Common symptoms include hard cold starts, excessive white smoke on startup, rough idle for the first minute, and longer cranking time in cold weather. A quick check is to remove the plug and test with a multimeter—if it shows an open circuit (no continuity), it’s usually failed.

If your engine uses multiple glow plugs and one has failed, many technicians replace them as a set (or at least check the rest), since the others may be close in age and wear. If budget matters, you can replace one and test the others.