03 with 271k. It has an occasional knocking sound as well as it stops gaining RPM at 2100 then starts a squealing noise. the knocking noise which only happens at low start off RPMs and then quits,  comes and goes but the RPM issue is constant. does this sound like a CP3 issue or something else? are the two symptoms related?

I remember an article about phase timing of the CP3 gear which can produce knocking.

3 hours ago, magammo said:

03 with 271k. It has an occasional knocking sound as well as it stops gaining RPM at 2100 then starts a squealing noise.

 

Check tightness of  fuel injector line clamps for knocking sound at idle or just off idle.  A friend of mine has an 07 truck that the engine knocked at low rpms and I was looking into re-clocking the CP3 pump when he noticed #4 injector line clamp vibrating.  I tightened the very loose clamp and the knocking sound immediately disappeared..

 

Check for broken or loose boost clamps between the turbo outlet and intercooler, and between intercooler and engine.  Also, check exhaust manifold for cracks or leaks.   Either situation could lead to significant loss of boost or drive pressure, and a squealing sound could occur as air or exhaust gases escape under pressure.

 

- John

 

I've seen a lot of 3rd gen 5.9 and 6.7 with warped exhaust manifolds causing the metal gaskets to act like a reed on a clarinet with the hot exhaust passing through them. Boost leaks cause squealing sounds also.

 

As far as knocking noise at lower rpm. As others suggested check injector feed lines. I've also seen injector cross over tubes loose and leak internally causing fuel knock. Failing injectors can be causing knocking sounds. ISB Common Rail injectors seem to mechanically bite the dust right around 100k miles and cause the low power / rpm along with very noticeable knocking sounds. I replace them all the time in the shop I work at. I've seen very few common rail injectors fail electronically or even set faults in the ECM.

 

Lastly how many miles has it been since the overhead was properly set. Tight valves can cause abnormal noise and loss of power. Valve lash sets to .010 on intake and either .020 or .026 on exhaust on a cold engine depending on year. The Cummins engine data plate will tell you what the correct valve lash is for your engine.

 

The picture is an amplified common rail DD15  injector that mechanically failed and caused engine run away from fuel pooling in the EGR cooler. There was not one fault related to injectors active or stored in the ECM. A full engine rebuild and $35,000 later the DD15 was running cherry again.

Edited May 25, 20186 yr by 04Mach1

11 hours ago, 04Mach1 said:

A full engine rebuild and $35,000 later the DD15 was running cherry again.

 

That's what it cost for my entire truck in 2002. This is just a rebuild... I'll skip the common rail world Thank You. That's just insane amount of money because of a CR injector failure.

The 07 5.9 I just built cost about $8500 for machine work, parts, and labor. The only parts reused we're block, crank, and external engine parts. All new parts were genuine Cummins.

 

I'm the same way as far as owning a common rail. I'm perfectly happy with my p-pump 12v and my VP44 24v. I have to say common rail engines are making me a decent living as a mechanic.