More on Kenworth inj. pump failure

[Prairie Dog]

So my mechanic buddy replaced his dead inj. pump as I described in this thread https://www.turbodieselregister.com/threads/250014-02-8-3-with-deceased-inj-pump and the truck runs great (though down slightly in power) but it has an odd issue.

For the entire life of this 2002 T-300 Kenworth, it has clogged fuel filters. It clogged the first one after a couple of thousand miles.
When you looked into the aluminum tank, it was black and you couldn't see through the fuel. The inside of the tank had a film of black stuff on it that you could rub between your fingers and it felt like fine soot.
He figured it had algae or something similar so when he replaced the IP, he thoroughly cleaned the tank out and replaced the FF.
After less than 2K it has once again clogged the FF and the fuel in the tank is quickly turning black with the same stuff.
He feels that it's soot but can't figure out how it's getting into the tank.

Any idea what this stuff is or where it's coming from?

Thanks in advance,
Scott

 

[mwilson]

Trying to think where the two could meet. Not sure if the "C" series has injector cups in the head with o-rings that could fail. I have to wander out to Service seeking info on a C-7 Cat anyways, I'll ask about the Cummins as well. The problem sounds familiar but I'm thinking it is a Detroit 60 series thing.

Mike.

 

[Prairie Dog]

Thanks Mike, we appreciate that. FWIW, this engine has the "CAPS" inj pump.

Scott

 

[mwilson]

Just talking this over, the only place in theory for this would be where the injector is set into the head.

First thing, take a fuel sample and send it out to verify combustion gases are present. Or just exactly what the black crud is.

There are two seals on each injector and the fuel from each injector does return through a shared passage and exits at the rear of the cylinder head. So it could be one of the seal rings or even the head itself. Just head scratchin' thus far.



The seal rings are shown here.....#25 and #26

Now the ISC service book is for both CAPS Pump and Common Rail fuel systems so this drawing even though it is for a Common Rail shows the fuel drain (return) tube on the rear of the cylinder head as that is used with both styles of fuel system.

 

[Prairie Dog]

Mike, cant thank you enough. I'll let my buddy know what you found and give him your suggestions.
If it's just the seals then at least it's a cheap fix for someone who can pull the injectors himself.

Cheers,
Scott