--Cracked Injector--

[JRG]

Could this be a cracked/leaking injector ???



Lots more off idle black smoke than before,



After long run times, a Very hard stumble off idle,



Currently 45k miles, NO box for last 20k+,



Fresh filters, oil, ect,



Power is consistant. (non-towing)



Anybody with any opnions? I have read lots of posts about cracked injectors, valve seats, adjustments,ect,ect. So i'm trying to figure out what things I can check on my own before talking to the dealer.



JRG

 

[edgerat]

what box did you have on it?

 

[JRG]

Check sig. (pressure)



Havent had box or any issues for last 25k miles. Just started.



JRG

 

[JRG]

Anybody with any suggestions



JRG

 

[cerberusiam]

What are your EGT's like?

 

[JRG]

Normal-- 600*-800* cruising

 

[edgerat]

ooops sorry I missed the sig, I have never heard of that box so it was my bad. I would have the injectors checked to see if any of them are cracked. When you crack a tip you crack the body of the injector as well, which gets spendy. I would be suprised if any of them were cracked for as much time as you have on them without the box on. Does the truck idle like a 24v? "Typical cummins rattle-rattle" idle?

 

[cerberusiam]

Normal-- 600*-800* cruising

How are the EGT's when you get after it? You have some of the symptoms of a bad railrelief valve. The excessive black smoke is usually accompnied by high EGT's while the ECU tries to compensate for low pressure. Is the Volumizer a pressure box?

 

[JRG]

ooops sorry I missed the sig, I have never heard of that box so it was my bad. I would have the injectors checked to see if any of them are cracked. When you crack a tip you crack the body of the injector as well, which gets spendy. I would be suprised if any of them were cracked for as much time as you have on them without the box on. Does the truck idle like a 24v? "Typical cummins rattle-rattle" idle?

Keep in mind the injectors are NOT factory, but a 80hp "clean up" Idle is good and quiet BUT... putting my foot on the throttle to 1500rpm makes a good vibration but stays fairly quiet.

 

[JRG]

How are the EGT's when you get after it? You have some of the symptoms of a bad railrelief valve. The excessive black smoke is usually accompnied by high EGT's while the ECU tries to compensate for low pressure. Is the Volumizer a pressure box?

I haven't noticed anything REAL bad. EGT could be a little high but by the time they get too high I'm going too fast . I would have to guess if the EGTs were climbing faster than before. I noticed yesterday that the smoke looked lighter (in both color and amount) when it was stone cold. I pulled the dip stick and oil level was good and seemed clean (black :-laf ) I checked the oil before starting. The Volumizer is a pressure box that also has a small amount of timing. I don't know my way around the underhood of a diesel real well yet, I would like to look at suspect items for leakage so any pic would be helpful.

 

[nps]

The relief valve on the rail doesn't leak externally so you won't be able to see it. It dribbles internally and prevents the rail pressure from building to the proper pressure. Pressure boxes have a tendency to weaken or blow them out, thus yours could have been weakened earlier and is getting progressively worse.



The only way to check it is to measure the rail pressure under load.

 

[JRG]

Just got back from a 3-4 hr drive. Let me tell you something IS wrong. At the end of the day there is a HARD stumble and lots of smoke at take off, at the next light the EGTs come down to only about 400*, although in the driveway I was able to get them to drop to about 300* by holding the RPMs at 1200 (very bad missing).



Q: 1) There seems to be a lot of oil residue around what I believe to be the injectors, is this common? (could just be from the valve cover)



2) Is there anything I can do at home before I call the dealer and look like an idiot?



3) Is it POSSIBLE this is a dirty/carboned injector issue?



JRG

 

[JRG]

The relief valve on the rail doesn't leak externally so you won't be able to see it... ... ... ... ... ... The only way to check it is to measure the rail pressure under load.

On another thread it has been stated that fuel can be seen leaking out. Anybody care to comment???





JRG

 

[JStieger]

On another thread it has been stated that fuel can be seen leaking out. Anybody care to comment???





JRG

My relief valve blew out between the sealing washers and rail return banjo fitting and covered the entire engine compartment and underside of my truck in diesel.

 

[JRG]

Excuse my stupidity, but where is the R. V. ?

 

[Diesel Nut]

Cracked injectors usually give a knock at idle.

 

[JStieger]

Excuse my stupidity, but where is the R. V. ?

Look at the driver side of the engine for the fuel rail from where all the lines to the injectors via the head originate. On top of this rail is the relief valve, which looks like a cylinder like object with a banjo fitting at the top of it. From the banjo fitting is a line that returns to the fuel fuel canister mount.

 

[JRG]

Thanks!



I was just reading another thread and saw a pic too.



Could The Injectors Be Carboned Up Thus Causing These Symtoms?



JRG

 

[nps]

On another thread it has been stated that fuel can be seen leaking out. Anybody care to comment???





JRG

In the other thread, the banjo bolt attached to the relief line has been removed in order to see the leakage. The leakage is inside and not visible under most failure cases - its the valve leaking the rail pressure into the return line.

 

[JRG]

let me get this right

So... .



If the relief valve was leaking internaly, it COULD cause

A) excessive black smoke at take off?

B) rough running just off-idle in N?

C) after 2-3 hr run time progressivly worsen w/ HARD stumble?

D) still have normal power levels?



If I were to take it to the dealer and he thought I touched the valve (check it in my driveway) would they give me a hard time?



FWIW- funny how I've been on this board for more than 5 yrs reading/commenting about others issues, THEN when something somewhat serious happens to you BAM!!!! deer caught in the headlights. Just need to take a deep breath... ... ... AH out with a smile... .



JRG