2004.5 injector knock or tappet noise?

[DaveH77]

Greetings,
I have a distinct 'light' knock that sounds a lot like my old gasser days with solid lifters, reminds me of rocker arm play, but hardly noticeable at idle, very noticeable under load or acceleration. Quite obvious when driving along a wall or building.
I assume at 276500+ miles that tappet adjustment would be a good idea.
No idea about work done previous to my last 53,000 miles.
Seems too light IMO to be a wrist pin or rod. OK, simple valve adjustment right.

Now I have read several threads that mention "injector knock", some saying so loud and hard that they thought it was a rod.
Also saying that the injector knock was just previous to injector failure, serious engine meltdown.
So now I'm getting a bit paranoid that its injectors not tappets.
Sometimes when its quiet on the road next to a solid bridge railing, it sounds light but very sharp like a spark plug wire jumping a big gap like when you pull a plug wire while a gasser is running.

This knock has developed over a few months, not getting any worse but it is somewhat new.
I don't recall it knocking like this back when I was chasing my severe surging problem, which I thought was a fuel or injector issue a couple years ago.
A new Timbo APPS unit cured all my surging issues completely. Ran way better than when I bought it, felt like a 'new' truck power and response wise. THANKS Timbo!!

Back then I had run a lot of different fuel cleaners and additives, chasing that surging, but haven't run them lately.
Going to run some DieselKleen the next couple tanks to see if it makes any difference.

Any suggestions, ideas, or insights into this knock are greatly appreciated.
Especially if you think it may be close to "injector killing a piston syndrome"!

Starts right up even when cold without block heater or even time on the grid heaters.
A little black soot on the bumper but no smoke or haze unless I mash it hard on the on ramp after 'putting' around town, even then, hardly any black smoke.
Throttle response and power are good, getting 16 mpg, even with light towing. (actual, not electric mpg)

I usually drive with a very light foot, seldom using the HP, about half time is in town daily driver in traffic and half running empty road trips. A little light towing, no EGT gauge but assume it never gets worked hard enough to get EGT up to 'clean' injector tips.

Covid killed most of my business and already tight budget, so new injectors are not a financial option until I get back to work. I need the truck daily for the little self employment that is left. Definitely a rock and hard place.
So praying it is not something real serious.

I guess dive in and adjust the valves because its probably past time anyway and maybe the knock goes away too.

I just thought I would ask you all if it sounds like it could be the dreaded injector knock.

If anyone is in Eastern Washington - TriCities area, it would be great to meet up with other experienced Ram Cummins folks.
Wonder if Steve ever gets out this way?
I haven't been around enough of these trucks to know what sounds normal or whats a red flag.

Thanks,
Dave

 

[sag2]

Start with the valve adjustment, it can't hurt and if you are handy at all it is a straight forward job. Might see if you can roll the engine over backwards with the generator nut, if you can't, spend the $30 for a barring tool.
After that, the only way to tell for sure is by capping off one injector at a time. The cap off tool is not that expensive. Look for Miller 9011 or aftermarket.
If you want to try a cleaner the only one recommended is CRC Diesel Fuel Therapy. Usually available at Napa stores. Double the label directions and then run it hard or disconnect FCA to bump up the pressure.

 

[DaveH77]

Hello sag2, thanks for the reply. Its been a lot of years since I adjusted valves but I need to bite the bullet and dive in there. It won't turn with any of the pulleys, tried that when I replaced the alternator. Need a barring tool for sure.
Thanks for the tip on the capping tool and cleaner, haven't tried that one.

Has anyone else out there experienced similar knock? Or any more input on injector knock? How often can one fail catastrophically with little to no warning?

THANKS!

 

[Ozymandias]

We aren't talking about the infamous injector rattle do we?

I got that often under medium load and rpm. Was told it's more or less common.

 

[DaveH77]

Yes, besides the valve adjustment, my main concern is injector knock. How common? How much is normal or a warning sign of potential failure and meltdown?
Surely someone out there has some input on the subject?
Thanks!

 

[cerberusiam]

Injector knock is noticeable all the time and it is usually loud enough it is obvious. Injector rattle on the stock VCO injector is common and most noticeable where you have something like a bridge railing or wall to reflect the sound. The injectors can be noisy like that and be perfectly fine. You are at the mileage where lack of filtering and lack of additives will begin to show by noisy injectors. A constant additive package, lube and cleaner, is recommended at this point to see if anything changes and monitor.

If it isn't making oil or hazing grey out the tailpipe constantly it is likely just wear and tear. You could get a cylinder contribution test done and see if that tells you anything more.

 

[Tuesdak]

After dealing with the knock on mine... Quietly sell it and buy a gas rig for now. Just saying on a tight budget you don’t need to be chasing an expensive knock.

Post a video of the knock.

Mine was knocking from a bent pushrod, a bad sleeve, head that looked like craters on the moon, and a separate knocking from the filter head valves due to low oil pressure. The injectors failed not long after the engine replacement as a rebuild F A I L E D in 500 miles. Hint never let a shop reuse an oil pump...