I've got a knock and I've let my truck sit for a few months. The truck will hardly start and it blows white smoke. A diesel guru I know said it sounds like the injector pump. I had another opinion saying that you can go through 2 motors before you would go through the injector pump. What could cause this knock and the symptoms i described. This is a dodge diesel with cummins.

 

compression check? did u pull the oil pan to check for damage?

 

Could be the IP.if you can listen close see if it sounds like it is coming from the top end our bottom. If it is in the top the most likely it is fuel knock. If you have a temp. Gun fire it up and shoot the temp of the exhaust manifold on each cylinder. If you have any that are excessively colder than the rest then those are you down cylinders. Sounds to me like you may have an injector with the tip blown off. Wouldn't hurt to pull the injectors. That would probably be the easiest think to check.

 

a knock can mean so many different things, stock lift pump will make a knocking/ticking noise when the cam gets worn out the rod will make a similar sound, or could be a loose rocker. you need to put a broom handle on the injection pump and listen to it