Im going to say its a piston slapping a cylinder. Most probably #6. Compression test would show. Enough fuel into the cylinder to cause a knock would produce grey smoke and an incomplete combustion smell. We rebuilt the engine in a truck that had the same problem and it was drove for a year with that problem.

Sent with a Droid RAZR in one hand and 14,000 volts in the other.

If its just 1 hole what do you do ?

Can you buy a single std HO piston and sleeve and have a machine shop install the new cylinder liner ?

If its piston slap I'd assume the cylinder wall must be toast ?

What is the cause of a scored piston in these I6's ? run low on oil ?

---AutoMerged DoublePost---

One other question on the truck with the burnt piston did it have a lot of blow bye ?
When i take the breather cap off while running it won't move the fill cap when flipped upside down. The blow by tube isn't puffing either. I also pulled the oil dipstick while it was idling and didn't even see smoke come out.

No the truck didnt have a noticeable amount of blowby. None of the ones with that problem have had alot. It is possible to just sleeve one cylinder and deglaze the others. Then put one new piston and rering the others.

The most common cause of this damage is the #6 piston cooling nozzle clogging and letting the piston get too hot and grow too much and make contact with the cylinder.

Sent with a Droid RAZR in one hand and 14,000 volts in the other.

Thanks for the info. I will see if i can narrow it down to which cylinder it is. I have a harbor freight cheapo compression test kit i used on my TDI volkswagen. There are a few different connectors not sure if there is one big enough for a cummins in the kit.

Lets say it is a bad piston cracking an injector line should not change the knock right ? it would only quiet it down it it was a fuel knock correct ?

Also the engine needs to be lifted up to get the pan off correct ?

when is that last time you've had your valves adjusted?

I just got the truck last week. The seller said they were done, but no specific mileage was mentioned. Listening to the tail pipe at idle there is no sounds of a loose/hanging valve though. Truck runs good pulls almost as much as my old 12v 5 speed that had the stock plate full forward, afc advanced and star wheel cranked some. Only time i have seen any smoke out of it was flooring it at 2000rpm in 4th.

correct the knock will still be there with a line cracked it might not be as loud but it will still be there. the harbor freight kit will work you will just have to grind down the one that is the correct thred because the body of the adapter will not fit in the injector bore but it dosnt take much grinding to get it to fit. cummins spec is min 350psi a good cylinder will be in the 450-500psi range a galded piston will be in the 250 range. yes taking the engine mounts loose makes getting the pan off alot easier but you probably wouldnt be able to see anything from down there unless it is a spun rod bearing. if you get a low compression reading in any of the cylinders then the head will have to come off.

All this makes me want to drop in a 12v. Run a manual cable for fuel shut, a switch for the grids,external voltage regulato and put my 6 speed flywheel/clutch on and go. . Wonder if my A/c would still work along with the rest of the wiring on my 01.

Around here 12V engines are more plentiful and cheaper. If its a 53 block in my 01 noway i'm going threw the hassle of machine work ect. Are all 24v engines compatible in my 2001 ? Ie all the same sensor locations on all 98.5-02 engines.

Hell, that'll work:tu:

I don't want to jump to conclusions before i get a compression test, but i think all signs point to a internal knock.

If it is internal damage and its a 53 block, i'm not gonna chance going threw a rebuild to potentially have the block crack at a later date. Engine swap required and noway i'm dropping $5k plus for a remaned longblock. Leaves me with the options of buying another used 24valve engine. I'm not even sure all the sensors are in the same spot on all 24v's, so thats a crap shoot and who knows how long before the VP lets go. I read on another forum a guy has a dead engine computer and prices were $1000-1900 for a new one plus reflashing.!!!!!

12v swap is looking sweeter all the time.

---AutoMerged DoublePost---

Ok i drove it to work today and when i got home i opened the hood and noticed the injector on the front cylinder is the only one that was moist. The more i listened to it the more it sounds like its the front cylinder. I listened underneath back by the flywheel and by the front tire. Noise really sounds more like from the top.

So i cracked the front injector open. It quieted down the motor some. (Mind you at full temp you don't really hear but a faint knock) BUT when i tightened the injector back up there was about 3 distinct knocks then went away. Tried this a few times and everytime the injector starts to tighten up 3-4 knocks. Like a high pitched tink tink tink. Tried a couple other injectors and none of them did this.

Hmm

Also for testing the compression is there a fuse or something i can pull so it cuts the fuel ? You usually pull out all the injectors first right ?