I just returned home from a camping trip up in the mountains and on the way home I noticed I had a knock coming from the motor. It occured shortly after I pulled a approx 3 mile up hill grade pulling my 5th wheel camper with my Polaris ranger behind it. I was watching my egt's carefully and never let the egt's get over 1250 pre turbo. My rpm's were running close to 3k in 4th gear and my engine temp went up a little but not overheating. I pulled the dipstick and level was fine and checked coolant and everything looked ok. Drove 40 more miles to get home and the truck ran just like it always does with no loss of power or excessive smoke but still had a slight knock that changed with the RPM. I let it sit awhile and then pulled dipstick again to check level to see if I had diesel dumping into my oil pan, but everything looked ok. Took to a diesel shop and we were trying to diagnose the problem when we discovered a pin was sitting in the crack of the G56. Dropped the tranny the next day to find out the clutch let go. So I ordered a SB dd3250 and had the guy install it. Go by today and guess what. That clutch was not the knocking noise. So we checked fuel rail pressure which was ok, then pulled the valve cover and didn't notice anything out of the ordinary. Got tired so I came home. I'am stumped. Do any of you guys have any ideas as to what I need to do to eliminate the obvious things? I hate to have him pull the head and start tearing into the engine. Is it possible that I spun a rod bearing or something??? He is almost positive it's not a fuel delivery issue, but I don't know. I only have 36k on the truck and hate to think that the motor is shot..... Called the dealer and they said my warranty expired last year on the engine and drivetrain.... It's an 06 so I'm expired on the time I guess. Any help would be greatly appreciated and if there are any Cummins techs out there in the Phoenix metro area that could give me some guidance, that would be nice...... Thanks guys.....

 

I would do a injector kill test to see if you can locate which cylinder might be causing the noise. Could also be injector causing noise. Pull oil cap and start engine any excessive blowby coming out. Check all the rocker arms also i have seen the little cap come off and the rocker arm will start hammering the valve. If you don't have access to scanner you can cap the injectors one by one at the rail. You can try cylinder % of contribution test if you have scanner, it will show if each cylinder and injector is operating at 100%. Any cylinder that is below 100% could be the suspect cylinder. If you spun a bearing it would sound like someone hitting oil pan with a heavy hammer.

 

Have you checked all the isolators on the high-pressure injection lines between the fuel log and the cylinder head?

 

Make a video for us, it would help if we could hear it.

 

going to have leak down test done and take an oil sample. Hopefully that will get me some idea to what is going on. Buddy took it to a friend at a dodge dealership and they checked with the scan tool and it had no codes. Ran some sort of test and may be a problem with cylinder #6. I guess I'll just have to wait and see. How much does a reman from cummins run anyways??? I don't know what to do... Truck runs fine but still has a slight knock coming from the bottom from what they tell me.....

 

well got my oil analysis back today. My iron, chrome, and aluminum seem awful high. Tell me what you guys think. They started the leak down test but only have done 1 and 2, so still waiting on that.....

 

Iron... crank, cyl walls, cam

Chrome... piston rings

Aluminum... piston

Everything described points to a mildly melted piston.

 

Anyone in the Phoenix area want to make some side $$$$ and do a rebuild.... Still waiting to see what 4, 5, 6, cylinders come back from the leak down test. The other three were ok i guess. I don't know what to do. Do a rebuild, go buy a reman... and ideas??? First three injectors looked clean with no carbon buildup. I found a youtube video of a guys cummins that had a bad wrist pin and it sounds just like mine does... What the hell, i just turned 36k and I already have problems like this. Very frustrating

 

from the oil analysis and "knocking sound", engine has a piston/cyl failure probably from an overfueling leaking injector nozzle or broken rings.

 

Injectors, I have the same issue right now 3 injectors failed and a 4th was boarder line. Truck still drives fine, just a knock.
These injectors suck, all I see are problems on here.

 

well I'am looking at having the motor pulled due to the readings we got on a leak down test. Number 6 was reading 43% when the other ones were I think were around 15 to 20. I still hope that it's not going to be major, but it sounds like it may be. I can't believe that I'm having this major problem with just turning 36k. I started searching for what to do if i need a rebuild. Trying to get qoutes and all........

 

with just 36K, i would just do #6 if the cylinder bore is good.

the labor will be high, 25 ish hours.

you can buy just a head gasket and o rings needed (not entire head gasket set), bottom end gasket set, piston and rings for around $600 plus oil filters coolant................shop supplies.................

reuse the head as is, they last forever.

dont pop the other 5 pistons out if you do that, you will have to re-ring it if you do.