No compression in Cylinders 4, 5 and 6 Help

You could buy a generator at harbor freight and a good battery charger with a 50amp start option. Then you wouldn't need ether.


If half your engine didn't have compression, it wouldn't run right and power would suck.

 

Would the exhaust have a strong diesel smell?

 

If it is not missing or shaking I would run it. Sometimes these 'techs' are not mechanics. If 3 cylinders were dead the truck would barely run. Some of these 'techs' would be wetting their pants if you told them to hold down an injector on a running Big Cam Cummins to find a miss.

 

Note in the technician’s notes, it said the 456 cylinders “mostly” had 0’s. That is suspicious.
The test they performed was a “software” test. Basically looks at the “speed” of the cranking of the engine using the cam and crankshaft sensors. Then extrapolates a number based on the results. A cylinder with strong/high compression takes more force to move, slowing the cranking speed.

Weak batteries or starter can cause erroneous information. I note that the technician stated that they had some slow or low cranking problems during this test and stopped. Seems odd with new batteries. Potentially a starter problem?

The technician also stated that the reason they did these tests was due to a noise or popping in the intake track. This could be a valve adjustment issue. One of the first things to look at is the valve adjustment. You said it had an overhead run just recently. It may have been done incorrectly.
The description leads thoughts to valve lash too tight. Checking the top end is a lot easier than some other things and may be where your problem is.