I have a F35o Diesel engine will not start, could be the glow plug ,It turn over good what do you think. Once I get it started , it starts right up
Otis

Yes, it could be. First, ensure both batteries are fully charged and that battery terminals and cable connections are clean.

Here's how to change the glow plugs:

With the engine "stone cold," disconnect batteries, remove valve cover, disconnect glow plug connector, remove glow plug with a 10 mm deep socket, install new glow plug (torque to 13 ft.-lbs.), and reattach connector. After finishing the remaining 3 glow plugs on that bank, clean valve cover, install new gasket, and reinstall valve cover (torque to 97 in.-lbs.). Do the same thing for the other bank of glow plugs and reconnect batteries. Not a difficult job--should take several hours