So the family and I were coming back from our yearly camping vacation, and on the last day of our travels, the truck started to idle very rough, and misfire with no cel. Then about halfway home, CEL came on and it threw a P306 code. It drove perfectly fine if it was above idle, however, and I noticed no loss of power while driving, and didn't see any white smoke. I got it over to our local trusted diesel shop, and got a call from them yesterday. They are saying that it looks like cylinder #6 has possibly lost compression, and they were going to do a compression test on the truck, and I would know more on Friday. So, worst case scenario, if I have a dead hole in cylinder #6, will that call for an engine rebuild, or does it make sense to replace the piston and hone the cylinder walls in just that cylinder? They are also going to be bench testing the injectors to see if they are the issue. Any help is appreciated. this is on a 2004.5 Dodge 2500 Cummins, with around 128,000 miles on it.

 

Wait to see what they find. Did they do a relative compression test on it? Is that how they know bad #6?

If if they are doing a compression test hopefully they leak down test it if they find a cylinder with low comp. it could be a bad valve or rocker or push rod or just out of adjustment. The leak down usually offers some insight

You won’t know the answer as to whether you can just rehone until the head is off and you can see the condition of the walls and measure the bore diameter and out of round. If you have a piston hole you have a bad injector

up to you whether you just replace one or all. I just lost an engine based on a bad injector. It very much sucked

Welcome to the Cummins time bomb club. Hope not, but it sounds like yours just went off! Kinda unfortunate that these are starting to pop more and more. The engine itself is great. Injectors not so much.


Chay