Background its a 2001 HO QCSB 4x4 6 speed bone stock with 220k miles.

So when i bought the truck last week i never really noticed this engine knock on start up. After i bought it the guy said by the way if you notice a knock its fuel knock on start up. He gave me a receipt from the dodge dealer from 2010 where they tried to diagnose it. He says they told him it was something in the ecm programming. In 2010 (60k miles ago) it had a new rebuilt pump and new stock injectors. It sounded like he wasn't fully confident on the IP install he did so he had it checked out and thats what they told him.

I thought the knock started after the new pump, but talked to him today and said no it always did it. Now i'm wondering if its not coming from the engine itself. Its definitely worse until its up to temp at 190F. Truck was a roll over in 2007 and wrote off. I wonder if something starved for oil ?

The knock is worse the first few seconds its fired up. Some of the lines are a bit wet at the injector.

If it was wrist pin/scored piston/bearing shouldnt the knock get worse with rpm ?

I noticed when you hog on it a little you don't hear it. When putting around when the revs drop to the 1000-1300 range you can hear it tap. Seems more pronounced with no load. Checked the oil no diesel fuel smell to it.
Oil pressure on the stock gauge seems ok. When warm at idle its a little under 40 or straight up. On the road hot its up around ~60.

Thoughts ?

Here is the video

Thanks

 

i couldnt really hear it till you shut it off. could be fuel knock. shoot your exhaust manifold at each cylinder with a temp gun and see how evenly they heat up. also are you getting any white smoke.

 

Nope no smoke and it does not seem to miss. No hard starting. Seems worse untill engine is warmed up to 190F.
Never thought of the temp gun thanks.

 

Sounds like an injector going south to me bro.

 

I'm hoping it is a fuel knock.

New VP and factory injectors were installed in 2010. They both have 60k miles on them. I got the receipts from him

I'm going to take the temp gun to it.

Did anyone notice the clatter when it shut off ? I noticed it only makes this "klank" on shutdown when its cold. When it first fires you can hear it knock real good 4-5 times.

In the video it was the 1st start of the day and only ran ~2 minutes.

 

id say fuel knock i work at a ford dealer ship and hear alot of this with a bad or couple bad injectors alot on the 6.0s

 

Thanks for all the input gentleman. I will report back with the temp light readings.

 

but idk with you saying no smoke, injectors out or staying open youd probably see some smoke

 

It's hard to tell. It almost sounds like it could be a knock. You could use a stethoscope and listen to different parts of the engine especially down towards the bottom of the block. Sometimes you can do the same thing with a long screw driver and put your ear on the handle but it's harder to tell that way.

 

The noise is definately worse untill the engine gets up to 190F on the stock gauge. So signs of smoke. Fuel knock does not change with engine temp though right ?

Got the infared gun but the batteries were dead, so on cold start i put my hand on the namifold at each cylinder for about 45 seconds going between them all. Appeared like the front and rear holes were slightly colder. Picking up some batteries today to do it with the gun.

I doubt its a bearing as the oil pressure is always up there. Maybe scored piston/wrist pin and with heat it expands a bit so tightens things up ?

Odd if its not fuel though that its been doing this for 60k miles and for over 2 years. Would have thought it would have blown up by now.