Dreaded injector knock

[Landon730]

Ever since I got my truck going after buying it in limp mode.. I've noticed that its nothing compared to the lb7 my dad had. Slowly it gained a injector knock... I'm only 16 so I can't afford a tool to read my balance rates to figure out which injector is bad (I can afford one MAYBE two injectors) . I can tell its the drivers side but I don't want to play a guessing game with something this expensive and I don't want to do like I did with 6.5's and break injector lines loose. The truck does just fine driving to work and hauling light loads but if you really start to load it and pull the knock gets extremely loud when you stop for fuel. I hauled a feeder on a gooseneck about 300 miles and that was the loudest the knock ever got. Almost sounded like a rod it was so loud. There's never smoke when pulling and just easing around but you can definitely hear a problem. I just need ideas on how to find out which injector is bad without breaking the bank. I want to get it fixed soon as I've already ran it about 3000 miles like this and just besides the fact of it being ridiculously annoying, I'm worried its not to good for the motor.

 

[THEFERMANATOR]

If it has a knock, STOP DRIVING IT! That's a GUARANTEED way to crack a piston or break the crank behind the #2 rod journal. As far as figuring out which injector, checking your balance rates is only a small portion of checking it. Without some diag tools, you're guessing. You cannot just crack an injector line open unless you want to pump the crankcase full of diesel, or chance cutting your finger/hand with high pressure diesel fuel(yes, it's that serious. 23K psi of diesel pressure can cut 2-3 inches deep through flesh and bone). You can't just unplug an injector because of how the ficm fires them in banks. You can pick up a elm and use the torque app or something for cheap to check basic pids, but thats about it for cheap.

But stop driving it before you end up like thousands of others who kept driving, ignoring exhaust smoke, and/or injector knock, and ended up with a blown engine because they wanted to get by for a few more weeks. You MIGHT get lucky, but more often than not it WILL break the crank down the road.

 

[Will L.]

Yeah, sux but Ferm is 100% on point. Starting it one time too many goes from a couple thousand to several thousand in seconds, even just 25 mph down the road.

This is the reason so many people stick with the older less powerful 6.2/6.5 or go gas engine like LS 5.7 or 6.0.
Newer more expensive rigs simply cost more for a reason.

This is the point you cancel the insurance and registration and let it sit until the money is saved, or sell it.

You’ll see me touting how great 6.5s are. They aren’t compared to dmax really. Just WAY cheaper to fix and they can be putted around until affording the fix can happen. And it isn’t just dmax. Cummins and ferds have the same issues on trucks newer than 2000.

 

[Landon730]

Yeah, sux but Ferm is 100% on point. Starting it one time too many goes from a couple thousand to several thousand in seconds, even just 25 mph down the road.

This is the reason so many people stick with the older less powerful 6.2/6.5 or go gas engine like LS 5.7 or 6.0.
Newer more expensive rigs simply cost more for a reason.

This is the point you cancel the insurance and registration and let it sit until the money is saved, or sell it.

You’ll see me touting how great 6.5s are. They aren’t compared to dmax really. Just WAY cheaper to fix and they can be putted around until affording the fix can happen. And it isn’t just dmax. Cummins and ferds have the same issues on trucks newer than 2000.

I know what you mean with a 6.5, one of my other trucks has 2-4 bad injectors and it has a injector knock and smokes black smoke like a freight train yet the old motor doesn't care. It sucks to do it but I'll park my truck until I get some injectors.

 

[Will L.]

With the 6.5- id which injectors are goofing up. Pull it and clean off the carbon by chemical and toothbrush. Do not scrape it. This will help/ improve many of these style injectors a bit.

You can also disassemble the injector and clean the interior, but may have to lap the sealing areas to get it to function afterward. Iirc there is a thread in stickies how to do this as part of rebuilding them.

Be cautious that an injector that is no longer misting, but shooting a stream can burn a hole in the piston if the stream is shooting through the port of the precup. If the stream is shooting at the precup it will just run poorly.

If you have the 6.5 truck, imo spend the money you have on new injectors for it if need be and drive it for now. Even if you risk damaging pistons from bad injectors. Far cheaper parts at risk.

 

[THEFERMANATOR]

With the 6.5- id which injectors are goofing up. Pull it and clean off the carbon by chemical and toothbrush. Do not scrape it. This will help/ improve many of these style injectors a bit.

You can also disassemble the injector and clean the interior, but may have to lap the sealing areas to get it to function afterward. Iirc there is a thread in stickies how to do this as part of rebuilding them.

Be cautious that an injector that is no longer misting, but shooting a stream can burn a hole in the piston if the stream is shooting through the port of the precup. If the stream is shooting at the precup it will just run poorly.

If you have the 6.5 truck, imo spend the money you have on new injectors for it if need be and drive it for now. Even if you risk damaging pistons from bad injectors. Far cheaper parts at risk.

My old 6.5 needs pistons because of bad injectors, hence why nobody wants it. Diesels are very unforgiving to running them with problems. When you're working with insanely high injection pressures and cylinder pressure that's high enough to bend steel plates, any problem is no joke.

 

[Stoney]

Just out of curiosity what do you guys use for a fuel treatment such as injector cleaners??Lucas?? Howes? I found some new stuff called k100.. supposed to be a good injector cleaner / lubricant for diesels.. I've ran it a couple times and seems to give you a little more horsepower to..but not sure if I would run it all the time without learning more about it... Not sure what condition my injectors are in. Never had them out

 

[btfarm]

I've always used Power Service. Silver bottle Summer and white in Winter. Another good thing for your entire fuel system is using bio (primarily soybean derived) fuel. Being from farm country, all the places I've ever bought from have B5-B20 in their tanks.

 

[MrMarty51]

I always run that Walmart 2 stroke synthetic oil in My fuel, cant remember the name of the stuff, something like TC3-???? I also use Stanadyne diesel additive. Dont know if it helps or now cause I have always run the Stanadyne. The two stroke oil, when I started using it,it did seem to make a difference. I gave My nephew a gallon of the two stroke, He started using some in His Cummins dodge, He said he could tell the difference in the way the engine sounds and the fuel mileage picked up some too.

 

[Landon730]

With the 6.5- id which injectors are goofing up. Pull it and clean off the carbon by chemical and toothbrush. Do not scrape it. This will help/ improve many of these style injectors a bit.

You can also disassemble the injector and clean the interior, but may have to lap the sealing areas to get it to function afterward. Iirc there is a thread in stickies how to do this as part of rebuilding them.

Be cautious that an injector that is no longer misting, but shooting a stream can burn a hole in the piston if the stream is shooting through the port of the precup. If the stream is shooting at the precup it will just run poorly.

If you have the 6.5 truck, imo spend the money you have on new injectors for it if need be and drive it for now. Even if you risk damaging pistons from bad injectors. Far cheaper parts at risk.

I have a couple motors laying around and I've got a dozen or more good injectors, just haven't changed them because its on the turbo side so its gonna be a pain lol.

Just out of curiosity what do you guys use for a fuel treatment such as injector cleaners??Lucas?? Howes? I found some new stuff called k100.. supposed to be a good injector cleaner / lubricant for diesels.. I've ran it a couple times and seems to give you a little more horsepower to..but not sure if I would run it all the time without learning more about it... Not sure what condition my injectors are in. Never had them out

Lucas has always worked really good for me. Had a 350 cummins in a international that had a injector knock from being ran without a fuel filter, Lucas actually cleared it up.