Hi everyone,

my 2006 2.6 CRD (141,000 miles) is giving me some serious headaches lately and I was hoping that more experienced users could help me with establishing what is wrong with the engine and how to proceed because at this point I'm seriously considering getting rid of the car. So here is how the story goes:

I've known the car for over three years prior to purchasing, was the main user for the past year (yeah, a company car) and finally decided to buy (the KJ was in pretty shabby condition but engine wise all seemed solid). First start (literally) after I brought it home and a new noise appeared A very distinctive knock coming from the intake, clearly audible with open airbox, resonating through intercooler piping.... A quick search and I thought it's clear - timing belt and rockers (seemed reasonable as I didn't have any info on the last belt change). Since then I've taken the car to a few shops, did some investigating and frankly I'm not so certain about the diagnosis any more. So first of all here is how it sounds:

https://www.youtube.com/watch?v=zpiMn2iidEo

The facts are:
- starts ok, runs ok, power is fine, there is a fair amount of smoke on heavier load but can't say if it's worse than before
- switching off individual injectors doesn't make the sound go away or change significantly (if it's backfiring through the intake it's on all 4 cylinders)
- MAF says ~18 g/s on idle, after a drive it drops to approx. 9 g/s and goes up with time, MAP at idle show ~102 kPa
- no ECU fault codes (P101 was present for some time but went away)
- while driving gently averages to about 20 mpg (thermostat is done, ~65 deg. C running temp, 2nd on the to do list)
- with cold pipe taken off the intercooler airflow isn't exactly laminar but definitely doesn't show as much back draft as on some videos posted on here from cars with skipped timing belts;
- guys from the Jeep/Chrysler shop performed thorough diagnostics and amongst other things claim that injectors and compression are fine, they also claimed that according to the tests it ain't the timing belt...
- I did all the usual filter/fluids/MAP&MAF cleaning/ran the car with MAF unplugged etc. - no changes
- Running on 5W40 (hard to say what oil grade was used before), drained oil didn't contain anything it shouldn't although I haven't dropped the pan to take a closer look.

That would be about it for now. Sorry for the lengthy description but I want to be as clear as possible about the symptoms. I will greatly appreciate all the help I can get in solving this as my patience is on its' limits!

Adam

valve issue. ya got one that isn't either opening far enough, or not at all. Or is bent and won't close. (or there's a chunk of glo plug jammed in there)
I have a perkins right now sounding exactly like yours. chop chop chop. Mine is a busted/loose valve seat.
slight valve issues really are pronounced at idle. They tend to 'disappear' at higher speeds. (still there, 'we' just can't perceive them as easily)

Do a compression leak down to see for sure... edit, I see you've had this done!
When you said 'fair amount' of smoke @ heavy throttle... mine is barely a haze. I can't say for others, but this tells me you are not getting enough air. Which a valve issue will knock the snot out of a turbo's effectiveness.

_________________
2006 KJ CRD, bought 9/11/14, 70,500 miles. Circulating Rotella T6 5w-40
11-3-14 oem stat installed
11-5-14 gen II FH installed.
Sasquatch elbow kit, samcos, GDE eco FT. 11-26-14
80,500 miles, engine is disassembled, awaiting parts 3/18
Budget?? Sure! 'Everything I have'.
New "Pet" name for My Jeep; 'Soul Sucker'

Could also be stripped plastic gears in the FCV allowing the plate to slap back and forth with intake pulses, or\and the worn EGR valve is clapping and you're hearing exhaust pulses thru the intake, muffled thru the CAC
- this would also cause black smoke

Intake valve not fully closing should result in some back-pressure puffing thru intake system from compression and combustion events, altho that should show up in compression check and injector-kill test - puffing might be noticeable by placing hand spread-fingered near (not across!) open intake duct

Not fully opening should also show up in cylinder compression comparison check

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

I think it's singled down to just 1 jug.. The frequency of the 'chugs' seems to fit with the 6 or 7 intake openings and closings per second @ idle.. for each cylinder. If it was a freed fcv, it'd be closer to 24-28 slaps per second.. almost undetectable?

LOL, I remember the first time I stuck my hand over an intake pipe! 903 cummins about ate my arm! "why? you ask".. well, why do kids stick their tongue on a frozen flag pole?..

_________________
2006 KJ CRD, bought 9/11/14, 70,500 miles. Circulating Rotella T6 5w-40
11-3-14 oem stat installed
11-5-14 gen II FH installed.
Sasquatch elbow kit, samcos, GDE eco FT. 11-26-14
80,500 miles, engine is disassembled, awaiting parts 3/18
Budget?? Sure! 'Everything I have'.
New "Pet" name for My Jeep; 'Soul Sucker'

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

It sounds exactly like mine did with a busted rocker. Mine "ran" fine with the exception of the noise.

_________________
2005 Liberty CRD Limited
DIY Garage Remanufactured Engine with GDE Full Torque Eco Tune from mile zero.
ARP Studs
Cummins Lift Pump
Transgo HD2 Reprogramming Kit
DIY Rebuilt Tranny Pump
Suncoast Torque Converter
2nd Generation Fuel Head
Sears P1 Battery
Hot Diesel Solutions Thermostat

Thanks for the input guys! So:

Valve train was also my first guess but it's the most cost/time consuming to actually pinpoint so I'd rather start with the simpler stuff (unless someone can be definitive about it). Compression was checked by an external garage, apparently with a diagnostic scanner only (didn't know they can do that). I'm thinking of checking it manually on my own. The car leaves a small black cloud on WOT but it always did that and it had a tune (boost up) done at the dealership, so I always thought that's the reason...


EGR is the first thing on my list to check - would be the easiest to take care of. I will take a look at the "intake puffing" again but frankly I didn't see much blow-back when I inspected it earlier (you can see it on the movie checked with a rubber glove).


darn you're right - didn't think of that but it's exactly 1 knock every two revolutions of the crank. I guess it's safe to assume it's a one cylinder issue?? So going along with this: disconnecting individual injectors didn't stop the sound so it's not detonation going into the intake, hence we're left with valve train sounds right (worn seat/bent individual valve or rocker)? If it were rods/big ends etc it should have double the frequency (i.e. once per crank revolution) - does that make sense????


Been seriously considering this but there were some voes against it from people more knowledgeable in KJs than me. Secondly I also got in touch with the author of this video: https://www.youtube.com/watch?v=cvmfPgvGWPo
Same sound, lot of money put into the engine and still the same problem, ended it with an engine swap X_x Would not like to go that route...

So to sum up, so far it seems like a valve train related knock limited to one cylinder. Can I safely assume it's not an internal problem somewhere in the block (big ends/rods/pistons)?

First thing I'll do is check the EGR: I'll block it off and if that won't help I'll pull the intake pipe off the manifold (disconnecting the entire EGR) - if this won't stop the sound it means that it's not EGR related right? Secondly I'd like to try manual compression testing inc. leak down. This being my first steps with diesel engines how hard is it to pull the injectors on those things? I don't have the VM tool obviously - any way around it?

The injectors pull out pretty easy,,, most of the time. Remove fuel line and return line. Remove bolt. Wiggle back and forth and up. If stuck, I've used a crowfoot pry bar to give a little leverage while wiggling.

Sounds like a broken rocker to me. My red one had two broken plus a bunch of worn out ones at 123k. It smoked pretty good. I replaced them all and it has been running smoothly and smoke free since then.

_________________
My collection of CRD's:
2005 Deep Beryl Green Pearlcoat
2006 Light Khaki Metallic Clearcoat
2006 Inferno Red Crystal Pearlcoat
2006 Midnight Blue Pearlcoat
2006 Gold Limited
2015 Black Ecodiesel
2015 Black Ecodiesel 2

You can't assume it, but it would be necessary to remove the intake for any of those problems as well. Worn/broken rockers are very common, and the most likely problem.

_________________
2005 Liberty CRD Limited
DIY Garage Remanufactured Engine with GDE Full Torque Eco Tune from mile zero.
ARP Studs
Cummins Lift Pump
Transgo HD2 Reprogramming Kit
DIY Rebuilt Tranny Pump
Suncoast Torque Converter
2nd Generation Fuel Head
Sears P1 Battery
Hot Diesel Solutions Thermostat

Sounds encouraging! When I'll be pulling the injectors and need to apply leverage I understand I should apply force to the "narrow neck" where the retaining brackets normally sit? Basically I saw some pullers that attach to the top of the injector via their threaded part but if I understand correctly the VM tool hooks up to this "narrow neck" on the injector as well? There is no thread holding the injector to the head, just the retaining brackets, correct?


Which part? The pessimistic version or the lack of internal problems - I guess both I'm trying to assess the problem as much as possible without taking apart half of the car. If it will be highly probable that it's something serious, I will either get a shop to take care of it or will just sell the KJ as is (don't want another car in parts on the driveway...).

I didn't have any real time for the Liberty so far (have to move the Nissan out of the garage), but still managed to notice one interesting thing:
I blocked the EGR inlet to the cooler (with a aluminum plate) and at first the knock, still present, became a lot less noisy, which gave me some optimism. On the other day's drive to work it became as intense as before. It turns out that unplugging the MAF makes the noise much louder, plugging it back in makes it a lot less intense. Made me think it might be EGR related, but upon some reading with my limited knowledge of how the system works I'm doubious: MAF unplugged, EGR disabled, FCV fully open, backfire more loud. MAF plugged in, EGR gas flow cut off at the cooler intake, FCV closes as much as it can and blocks the intake significantly to try and improve exhaust gas flow to the intake, backfire less loud. Makes sense? Any opinions?

Btw. after blocking the EGR cooler intake I got P299 and P401, but I understand these are to be expected.

The injector is only held in by the retaining bracket. It is not threaded.

_________________
My collection of CRD's:
2005 Deep Beryl Green Pearlcoat
2006 Light Khaki Metallic Clearcoat
2006 Inferno Red Crystal Pearlcoat
2006 Midnight Blue Pearlcoat
2006 Gold Limited
2015 Black Ecodiesel
2015 Black Ecodiesel 2