I recently removed the P-Pump on a 12V Cummins in a piece of heavy equipment to fix an oil leak. I pinned the pump/engine, cleaned the gear and shaft and torqued the pump shaft nut when I reinstalled it. It fired up and ran fine. We ran it for a good 15-20 minutes to make sure the oil leak was fixed and all seemed well.
About a week later I was informed that the engine was making a “bad” noise. I can’t seem to tell where this noise is coming from. At idle there is a loud sound, it almost sounds like a vacuum leak, however, I believe it is a lifter. The noise goes away when the engine is throttled up. I don’t feel this noise is related to the previous work done or the injector pump being removed because the engine runs strong and has all the power it did before.
My question is, if a piece or trash got into an injector line before the pump was installed would it cause a noise such as this? Is there a common problem related to this symptom? I was told by the operator that this engine broke a valve spring a few years back and was making a "bad" sound.

 

i would get the heat gun out and start looking for a colder cylinder

 

I took a temp gun out and shot the exhaust manifold it seemed to be around 475 on the outer cylinders and 500+ on the inner cylinders. I was also able to shoot the tappet cover it was under 200 on the outer cylinders and over 200 on the inner cylinders. The cylinders seemed to be consistent with each other 1&6, 2&5 and 3&4. The exhuast is directly on top of the valve covers on one side and the air filter housing is on the other side so there is no real access to the top of the engine, there is also limited access to the exhaust side of the engine. Where is the optimal place to check the temperature of the cylinders?

 

I'm not a Diesel tech, and I don't play one on TV, but, I think the manifold, as close to the head's port outlet is the best you're going to do for a heat-reading source. If 1/6 are near-equal-cool, 3/4 near-equal-hot, 2/5 intermediate, and all inside of about a 30*-40* range, you don't have a bad injector problem. Look for some other source for the "bad noise".

 

Is the kdp tabbed? Tappet issues typically don't just show up. But we all know how folks treat someone else's equipment so who knows when it really occurred. If it was valve train related a stethoscope would probably pinpoint it very quickly.

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IDK about the KDP, but I doubt it has been tabbed. The tappet cover wasn't really leaking, the injector pump was leaking oil where it seals to the timing cover. While the injector pump was off we replaced the tappet cover gasket. This week I am going to pull the valve covers to inspect the valve springs.