First thing I would try is to see if noise happens with out tune.

 

Thanks. I did try that though. Makes the noise whether autocal set to stock or race. Or the 3 tunes in between.


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If the oil analysis looked good then it’s probably safe to say the bottom end is ok. It sounds like a fuel knock due to one of the injectors dribbling fuel. I’d try to get a scan tool that can turn off the injectors one at a time to find the culprit cylinder. It’s not the cp3 “timing” noise is it? That’s more of a rattle tho. On second thought the noise might not go completely away if the injector is dribbling but it should change the sound when you cut that cylinder with the scan tool. I’d say it’s a bad injector especially at that mileage.

 

Since noises can travel/reflect, I would try to narrow down, old school with screwdriver/wooden dowel to ear or mechanics stethoscope, like this https://www.harborfreight.com/mechanics-stethoscope-63691.html

 

May be a valve out of adjustment or dropped valve seat. Or loose injector. Check and set the valves. Test for a dropped seat. Any bent pushrods? Do this one first, can have drastic consequences.

What's the warm idle, 60mph cruise and WOT steep hill rail pressures?

May be dirty injector nozzle with uneven spray pattern. Try a double dose of PS DK and 2 oz per gal of TC-W3 outboard lube in tank. Hook onto something high wide and heavy, head for the hills and try to burn the guts out of it. Keep EGTs under 1300d F.
Continuous use of a quality injector cleaner is necessary in rigs only used as boy toy play rigs with no heavy towing.

 

May be a valve out of adjustment or dropped valve seat. Or loose injector. Check and set the valves. Test for a dropped seat. Any bent pushrods? Do this one first, can have drastic consequences.



What's the warm idle, 60mph cruise and WOT steep hill rail pressures?



May be dirty injector nozzle with uneven spray pattern. Try a double dose of PS DK and 2 oz per gal of TC-W3 outboard lube in tank. Hook onto something high wide and heavy, head for the hills and try to burn the guts out of it. Keep EGTs under 1300d F.

Continuous use of a quality injector cleaner is necessary in rigs only used as boy toy play rigs with no heavy towing.

Actually did the valve lash adjustment maybe 6 months ago. I guess I’d categorize it as a daily driver based on my mods, but it does get driven far from daily. I put on less than 10k/year and out of those miles I’d say close to half are pulling either my 5th wheel camper with 16 ft boat behind that, or pulling my ASV on a gooseneck trailer @ 12k gross trailer/skidsteer weight. Last night I ran it about 150 miles after putting 24 oz mixture of ATF/2SO mix and topping tank off. My next step will be pulling the valve cover just to DOUBLE CHECK my valve lash adjustment. They really were close to right on when I did them, but no sweat to check again. Biggest reason I’m leaning toward possible injector is after reading the threads about DAP supposed “new” injectors that are actually remans. Maybe true maybe not I guess, but enough reading to make me nervous about the noise and the fact that I have replaced one injector year and a half back or so. A friend with more knowledge of these diesels than me is more suspect of my noise being caused by air somehow in the system. Will have to do some research to see if there’s a good way to bleed the fuel system in my truck too[emoji106]


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Your friend isn't doing you any favors with that suggestion. Air in a CR system means a no start and no run, that is pretty definitive. No real way for air to get in anyway as it is pressure fed from the in-tank pump, if it suck air it doesn't pump and engine won't run.

Injector rattle with stock injectors is a fact of life, that is just the way the VCO nozzles work and the effect of spray pattern. Add to that the tolerances on stock Bosch injectors is +\- 3% and a rattle, or even a small knock, is not unusual. The only way to get rid of that side effect is a higher quality injector build with better QC.

As for your existing injectors, look at the top of the solenoid and record what numbers are stamped there. If there are ture new late model Bosch injectors you will have stampings there that indicate revision, build date, and location. Have to document what you actually have before suspecting problems.

Injector rattle or knock can also be caused by carbon buildup on the nozzles, generally from DD usage and no hard towing with extended temps. Load it up with as much weight, or as much air restriction as possible, with a heavily treated tank of fuel and run it with EGT's up around 1000-1100 for a couple hours. If it is a carbon problem the symptoms should diminish and overall running smooth out.

 

As for your existing injectors, look at the top of the solenoid and record what numbers are stamped there. If there are ture new late model Bosch injectors you will have stampings there that indicate revision, build date, and location. Have to document what you actually have before suspecting problems.

See if I can make this make sense. Stamps on injectors are as follows...

Haven’t gotten back to #6 yet, don’t know if I’ll be able to see numbers off that without pulling it out, but based off these numbers, can you identify anything out of the ordinary other than that #3 is the injector I replaced about 1.5 years ago?

1-
0051 114
927 69003
1991
2-
0051 114
927 69003
1995
3-
3316 238
927 20203
3323
4-
0051 114
927 69003
2001
5-
0051 114
927 69003
2007



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Thanks cerb. Only thing for air that made sense is I recently changed filters on my Fass setup, but to my knowledge the Fass pump pulls fuel through the filters, and part of the job of a Fass system is to eliminate air anyway. So if air got in the system pre-pump I assume the Fass would’ve taken care of it


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Numbers didn’t exactly line up like I typed them in, but other than the number I assume is a build date not lining up under the bottom right one, they’re kinda close to what it looks like


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What numbers ar eon the top of the solenoid? Number 3 looks to be the latest revision if 238 is stamped on top of solenoid.

 

As you’re looking down on the top of injector, each one has 4 numbers stamped in it. Going from top left, top right, bottom left, and bottom right. Bottom right also has a number stamped under it which seems to be a date. For example 2001,2007, but on number 3 it’s an oddball number in that place, so hard to tell if it’s a date or not


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Any injector that has numbers stamped on them is a production injector, Bosch is the only one that uses that to be able to differentiate between remans and new. Those numbers mean something but it is a secret squirrel code.

 

Ok. So there’s really no way to identify for sure based off the stamped numbers whether they’re a new injector or they’ve been remanned? Just that it is in fact a Bosch injector?


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There is, Martin at BBI could tell you what all the numbers mean. I *think* the fact the numbers are stamped on the solenoids means they are new NOT remans, pretty sure any reman, Bosch or otherwise, would not have numbers on the top of the solenoid but check with Martin.

Looks like the last one you replaced is the latest revision, 238. The rest are consistent with an earlier revision, 114, with hard chrome internals where needed but missing the silanized bodies, which was really for marine usage, and some low pressure functionality changes. Martin would have weight in what that really means for effectiveness because some of the updates really did not affect operation.

 

The silanization process that Bosch uses on the later HPCR bodies creates a thin durable wear resistant protective rust preventative surface. Critical in marine diesels exposed to far more water than road injectors, especially from active microbes reproducing in the diesel and producing water.

 

Is it really a knock or is it more the normal injector rattle stock injectors have? I know it is hard to differentiate which is one is which without an audio clip, but, a knock would be like tapping on metal with a hammer where the rattle is more like shaking marbles in a tin can. A knock from a mis-fueling injector is steady like a metronome in relationship to rpm where injector rattle is more varied in its pattern.

 

Thanks for the explanation of the difference in sound. I’ll TRY to get a clip posted with sound tonight. It definitely gets more distinct and louder with load and higher rpms. Part of me hopes it’s an injector rattle, but without knowing what “bad injector” knock sounds like, I’m at a loss to guess what I’m hearing other than hard parts being suspect.


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Actual fuel knock sounds a lot like a rod bearing in gas motor. The loudness doesn't vary much, just frequency as it follows rpms. If it is varying like you describe it is likely injector rattle, but, every once in while you hear of a CR motor that spits a rod out the side of the block. One would think that event would be presaged by some distinctive sounds.

 

Good to know. That’s actually what my gut feeling of the sound was. Rod bearing. Really don’t want to have to deal with that. But though I don’t understand the logic behind injector knock, or what is actually creating the noise, it does make sense to me that if there is a noise, that it would get louder with both load and rpm due to the increased RP correct?


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Not always as the source is really different than what you think. Fuel knock in a diesel is really detonation, 2 sources of fuel igniting and flame fronts hitting each other. There is a delay in the 2 pools of fuel igniting because the injected fuel is atomized well and fires off easily. A pool of fuel from dribbling injector(s) takes longer to ignite so there is an ignition delay and flame fronts hitting each other. The pool of delayed ignition fuel is close to the same all the time and flame fronts hitting do not necessarily vary loudness.

It will vayr some but not like injector rattle which is more like spark knock in a gas engine. In a diesel it is the spray pattern and mini flame fronts touching that rattles, ie small amounts of fuel.