CAT 71D engine problem

Don't panic yet😊
What kind of noise.....just compressed air???
The glow plug is screwed into the pre-com chamber and sees combustion and compression....may just have just come unscrewed.
Now if the noise is a loud mechanical sound you may have other issues.

71D is the model, D318 is the engine.

The noise is compressed air. Pardon my ignorance but I have not ever taken out a glow plug before. I removed the adjacent glow plug and compared the two. They look the same but I think they are both worn out. I believe the glow plugs are supposed to have an end like a bulb aren't they? The heating element on these runs throught the center to an open end. Are they hard to find?

The glow plugs are easy to come up with. The heating element on the end is straight and a little rounded on the end, no bulb.

Here is one source....don't know anything about them.
Part number is 3H2033....as Walt66A describes.
http://www.truckengineparts.com/search.aspx?find=glow+plugs

I didn't do a good job describing the glow plugs. What I pulled out is a tube- open at the bottom with the heating element in the center. I am assuming that the glow plugs are supposed to have a solid end or cap of some kind on the bottom. Without an end, there is nothing to contain the compression. I appreciate all the advice guys. As I have said before- this is the best site to ask for help.

Yes, they should have an enclosed metal jacket, configured sorta like this picture:

I got my new glow plugs from my most excellant CAT dealer (Wyoming Machinery). Now any tips on installing them? Do you use anti-sieze on the threads? Torque them in?

Yes put a little anti seize on them and the Cat owners manual says torque them to 10-12 lbs.