hey this is kyle and im new to the site. but i seriously need your help. i just bought a 01 f350 single wheel ton 7.3 powerstroke 6 speed 4x4.i am the second owner and it has 115k miles. truck has a 6 position ts chip but other than that is stock.i bought the truck a couple days ago and it has been perfect untill today. after driving home from college back to my apartment i noticed a knocking sound. cant tell where it is coming from on the motor. the guy i bought the truck from said he just had the truck serviced a couple weeks ago. oil level is fine and no leaks that i can find. PLEASE HELP

 

can you elaborate more on what the knocking sound sounds like? ball peen hammer hitting steel ? or??

 

thats pretty much what it sounds like. ive never heard a powerstroke with a rod knock but it sounds alot like a gasser with a rod knock

 

The knocking noise *might* be injector #8; it's a known issue/characteristic of these trucks. Several vendors sell a "high pass crossover" kit; it's basically a connector that connects the heads to each other & helps minimize the amount of air in the fuel. Air in the fuel is bad for your injectors & makes things noisy, especially the #8 injector.

 

the ball peen hitting steel sound is generally caused by a "long leed" injector in the #8 cylinder put there by ford as an attempt to cure a fuel deadhead problem.

Normal, however, you can compare it to another powerstroke, maybe see if it's the same.


EDIT: brendan beat me. also, if you fuel tank is below a quarter tank, it could be allowing some air through the tank by all the sloshing around. I have heard guys say there trucks get louder under a 1/4 tank (air)

 

so whats the fix? new injectors? how much money? and just in case it is worse than the injector and it is a rod, does anyone have any idea how much that might cost to fix? and the knocking speeds up as it turns higher rpms

 

Mornin Kyle,
Sounds like everyone already has you pointed in the right direction. some folks have had results with this: Riffraff Diesel: Fuel Rail Crossover™
Everyone that has done the in tank mod seems to highly recommend it. You can also find helpful information from these vendors:
Riffraff Diesel
ITP Diesel, LLC
Both have a good reputation from what I have seen. They are both willing to talk to you about any issue that you have and a possible fix.I looked at your location and you are in TN, correct? There are several people on here from that area and you might be close enough to someone to meet up and check out your situation. Also, you are extremely lucky because last year was the beginning of a little get together that was started, something like RRE, IIRC.( )

 

possibly the easiest way to determine if it is an injector is to find a road to "coast" on, or a road that is slightly down hill like a freeway off ramp.

as the trucks rolls along, let off the accelerator. if the noise gets quiet, the add some light pedal. If the comes back, add some more pedal to see if the noise gets really loud. I don't recall rod noises comming and going like injectors, but I have been wrong before.

the bearing sizes and design of the engine pretty much prevent rod bearing failure UNLESS the chip allowed more than 400 hp, but it takes some serious mods to get there, and you'll usually fracture the rod first.

 

This might help explain it.
Try a google search for "diesel cackle"

dieselmann's editorial

 

For a quick check, replace your fuel filter and see if it gets quieter..

 

I have a 'highly modified' fuel system, and I tend to disagree that the 'fuel rail crossover' or any 'cackle repair' kit solve ANYTHING. Trust me, I have had more air in my fuel system than anyone with a 'stock' fuel system. I can also open up the 'test ports' and remove said air almost instantly. Yes, the injectors are noiser when there is air at the end of the rails, but nothing like a 'rod knock'. I researched all of this cackle stuff long ago and it dates back to the 'old skool' guys being frustrated when Ford changed the fuel system design from the OBS trucks. Since then, many vendors have made a buck selling kits like the old timers put together... and human nature is to justify your decisions, so most people feel like they've done something after spending the time/money on such 'mods. (flame suit ON! )

Back to your problem. I suggest getting a real scan tool like the stealership uses, or hopefully finding a local forum member or shop that has an Auto Enginiuty or similar tool that can perform an 'injector buzz test' and 'cylinder contribution test'. Even if you have to pay someone for this diagnostic, it'll be cheaper than throwing parts you don't need at your new truck.

In the meantime, relax! Your problem is not likely serious at all. These engines are TOUGH. They are quite complicated though, and surprisingly small things can seem like big problems! Please tell us more about your truck, since until ya get 25 posts ya can't fill out your signature... What year, miles, mods, etc. What kind of chip and what programs? (bug the PO if ya have to - this is VERY important to know!! )

IF you need an injector or injectors, this is not a horrible job and most mechanically inclined people can handle it with the tools they already have. Its not like a swiss watch in there, its just nuts and bolts. The only real headache is getting to the injectors - and you can see the things that are in the way of removing the valve covers. I have to strongly recommend upgrading to 'single-shot' injectors if you can. A set of these will set ya back about $1600 plus new tunes for your chip - but ya get 2-3 mpg better fuel economy OR 50-60hp and maybe 100ft/lbs of torque, depending on how you stand on the skinny pedal. (mine are from Swamps Diesel Performance, near Nasheville - GREAT guys btw!! )

The fuel filter is the easiest thing you can do right now. I suggest adding a peice of hose to the end of the tubing on front of block where fuel bowl drains out. I have this tubing extending down low enough I can collect the contents of filter in a water or soda bottle for inspection. I just leave it there, but lots of people ask what its for and think something has 'fallen down'. LOL!

 

Welcome to FTE, these motors are noisier then the gassers especially when It's cold, your problibly not used to it yet. If its bothering you by all means take the steps above mentioned and you will find out for sure or at least clear your mind of any dout. I experienced those loud knocks before, sounded like what you explained, like a hammer hitting the inside of the block but it would come and go. Running synthetic oil and diesel fuel treatment you can try also, good luck.

 

Welcome!

I agree it is probably just your #8 injector. It is easy to think it is something major because of the noise that it makes. I have a new motor and it still catches me off gaurde sometimes.

Not much need to worry about it being a rod knock because these truck generally dont just get a rod knock like gassers do. They just shoot them out when they brake. LOL

 

LOL, sure seem's like case anymore..

 

What has changed in the last couple of days besides the knocking?

If you have less then a 1/4 tank of gas fill it up. These fuel gauges aren't totally accurate and it may be lower then a 1/4 tank and you could be sucking some air into fuel system. When these engines start starving for fuel they knock like crazy.