I have an 02 Excursion with the 7.3. She is mostly stock with 96K miles. I have done nothing to the internals of the engine nor any fuel system mods. I have done the oil crossover line, 4" exhaust & Ford AIS. I run Rotella 5W40 synthetic oil that is fresh. The fuel filter is fresh and I run B5 diesel.
I get a knock at idle after warm up. At first I thought it was injector noise but it does sound like a rod knock that is very faint. Are there any fixes for this such as fuel system mods like the Air Dog or the Reg return kits or is that not the problem?

Thanks,
Brian
Herndon, VA

 

You might have a weak fuel pump. I changed my fuel pump 3 times because of idle knock, then I unpgraded to whats in my sig, problem solved.

 

Nothing you will do can get rid of that #8 idle knock.
It doesn't really hurt the engine.

 

Really?
I have the in-tank fuel pump, air free fuel, and brand new Alliant injectors and the thing knocks all the time.
I gave up on that and just live with it.

 

Its true, I have zero knock at idle. Last time I checked my fuel pressure was at 75psi also. I can hear a faint knock when its time to change my fuel filter, but thats about it.
Edit - I also dont have a LL injector, if it matters.

 

What is stock presssure normally at?Not doubting just curiuos.

 

I think 55psi is stock, if your pump is in good shape. Also most guys have their pressure set at around 65psi if they have a reg return or shim.

 

Wow, ok, I guess I am just unlucky on this one.

 

What causes the #8 knock?

 

It fires right after the #6, and fuel supply to the head is at the other end at the #2 injector.

 

I had that problem too until I started using fuel additives. The best one that stopped for the longest time was Wal-mart's Supertech, TC-W3 2 cycle engine oil. Mixed at 1 oz. per gallon, my truck runs, smoother, quieter, and way mor efficiently. No knocking, no other strange noises, just a quieter, smoother running PSD.

Your results may vary as these engines have their own personalities and like certain things as opposed to others.