TC45D has occasional knock

[Professor Marvel]

NH TC45D 2003 1600 hrs

Recently i have had an occasional knock. It can run for a long time and once in a while a short time runs fine and suddenly it develops a knock. I always shut it off and start it up later to try to find the issue and it sounds fine again. Changed oil (shell rotella T6 synthetic and NH filter)and same problem. It does not matter if weather is hot or cold. Today I pushed snow and didn't hear any issues. When I was getting ready to shut it down I backed the throttle down and it started knocking. I speeded it up and it went away. I slowed it back down to idle again and this time it purred just fine. My friend thought it might be a lifter sticking and suggested I put fuel conditioner in.
WHAT SAY OUR EXPERTS HERE??
Thanks for any help

 

[Professor Marvel]

ordered this
Stanydyne Lubricity Formula
i will see if it helps

 

[jabelding]

Might be water in your fuel, have you checked the bottom of your fuel filter lately?

 

[Professor Marvel]

no but i will now. Can i just open a screw at the bottom of it and drain it?

 

[missesalot]

no but i will now. Can i just open a screw at the bottom of it and drain it?

Not on mine, have to unscrew the metal ring that holds the jar on. Mine was froze like **** this week. I added Howe’s Diesel treat. Ran like a top after that, better than ever actually.

 

[Professor Marvel]

thank you for the heads up
will try that

 

[DieselMonk]

Sounds like it could be the lifters. Water or gas mixed with the diesel fuel will cause havoc too. You can try to add a can of seafoam to the engine oil. That will clean the little oil passages inside the engine.

 

[Professor Marvel]

thank you

 

[DwayneB]

thank you

A lack of or too much fuel from a single injector will sometimes sound pretty bad.

 

[Professor Marvel]

Looks like you were all right. It was getting bad quickly and I did not want to keep trying to figure it out myself and possibly ruin what might be saved so I had the local NH dealer pick it up. It had large amount of water in the tank. I always keep it over full to avoid condensation but I guess that wasn't enough. OH also a squirrel had chewed the vent cap off my fuel cap and we have had incredible amounts of rain around here for at least a year likely contributed to water.
Anyway fuel filter clogged with large amounts of rust. Injector spring broke so wouldn't close and dumped fluid (water and fuel). He said should be fine. They are going through entire injector system since they have it. Will get it back next week to find out for sure. This guy first told me (when I said it had a knock) that if it was a bottom end issue probably best to just get new motor but not worth it on 2003 unit. SO THIS MADE ME FEEL A LOT BETTER.

Thanks to everybody for your suggestions. Would have looked farther into what you folks said but did not have confidence in myself.