Why do the LB7 injectors fail?

[chrisinkanata]

Is anyone aware of a diffinitive cause the injector failures of the '02 Duramax? I had all of mine replaced a couple of years ago and the truck still runs perfectly. Excellent fuel mileage, no starting issues (even when I forget to plug it in at -27C). I have had a Kennedy filter system installed for several years as well. It was intalled not long before the first set of injectors quit, so the 'new' ones have never been without it.

I guess my question is, can I expect a longer injector life with the upgraded filter system. Another couple of years and I'll be over the 7 year warranty period. It's only at about 100K miles now so the mileage won't be an issue from a warranty perspective.

Any thoughts?

Chris

[Mark Rinker]

I think it will be hard for anyone to 'definitively' claim a common and absolute root cause. In my mind, injectors are a wearable part than can have drastically varying lifespans, depending mostly on fuel quality.

However, you are 'definately' taking all necessary steps to avoid this problem in the future, and that is a very smart thing to do!

After examining many fuel filters, there is alot of rust and other contamination that make their way into the system. Sure seems like the root cause to me!

[SoTxPollock]

I believe in the extra filtration as most everyone on forum, you did the right thing. I had 20,000 on mine before I put the extra filtration on, its coming up on 98,000 now with no problems. I like you hope that continues. I personally believe that one other thing helps. A fuel injector is a very precision part and clearances for it to operate are so critical. That is the reason I never have just cranked up and pulled out on the street and nailed the petal to the floor. I strongly believe in a proper warm-up to operating temperature before asking those injectors to work hard, I have no way to prove what I'm saying is true, but every mechannic, technition, performance writer will alway say be sure its up to operating temperature before you lean on it hard, if you want it to last. All components of differing types of materials have expansion and contraction rates that are unique to their chemical and physical properties. Until everyting has reached its normal operating temperature the clearances are not what they were designed to be. Its a simple little thing, but possibly one of the important ones.

[dieseldummy]

While I'm sure that extra filtration can't hurt, I don't think it has been proven to help. I wonder how injector bodies can crack for reasons other than poor design or casting? Rumor has it that there is another "redesigned" injector out for the LB7... Hopefully it is the cure all.

[Duramaster]

High pressure plus small particles equals damaged injectors. Also, one of our GM reps once said that you would expect to replace the injectors at around the 100k mark anyway. It's common maintenance in the larger diesel engines (CAT, CUMMINS, Etc.).

[StrangeEngine]

High pressure plus small particles equals damaged injectors. Also, one of our GM reps once said that you would expect to replace the injectors at around the 100k mark anyway. It's common maintenance in the larger diesel engines (CAT, CUMMINS, Etc.).

Your GM rep is full of sh*t. If that were true, the heads would not require removal for injector R&R.

- Mark

[beeler]

High pressure plus small particles equals damaged injectors. Also, one of our GM reps once said that you would expect to replace the injectors at around the 100k mark anyway. It's common maintenance in the larger diesel engines (CAT, CUMMINS, Etc.).


While I agree that injectors are somewhat of a tune up item and should be changed every now and then, these are too expensive to do that. In the early '90s I had a Ford 7.3. I dropped in a set of reman injectors every 30-50 k miles. Cost was under $300 and a couple of hours of my time. Was worth it in improved performance and milage. With these modern engines and the $$$$ involved nobody is going to change injectors without a failure. Is this progress?

[Duramaster]

Not to argue with you STRANGE, but I have never had to remove the cylinder heads to replace the injectors. Care to explain?:confused:

[StrangeEngine]

Not to argue with you STRANGE, but I have never had to remove the cylinder heads to replace the injectors. Care to explain?:confused:

My understanding is that on the LB7 motors, the head needs to be pulled to replace the injectors. This was remedied on the LLY trucks.

There's plenty of info on this here in the archives.

- Mark

[DmaxMaverick]

My understanding is that on the LB7 motors, the head needs to be pulled to replace the injectors. This was remedied on the LLY trucks.

There's plenty of info on this here in the archives.

- Mark

Valve covers, not the heads on an LB7. The LLY valve covers have a relief in them for the injectors.

[Gnostic_1973]

The change interval is not 100k and the person that told you that had no business saying that to you. The filters on the trucks are good and protect the fuel system, but there is system dirt that erodes the injector internal parts. Remember that the pressures are high and there are components in the injector that are subjected to very severe conditions. The particles essentially sandblast the area that separates the high pressure and low pressure sides of the injectors. There is not a casting flaw just severe environmental conditions. The condition was corrected by Bosch and GM and the important thing to remember is that GM did the right thing and extended the warranty on the injectors to 200k to make sure the customers get a top quality, long lasting product. This is in complete contrast to what Ford has done with their customers when they tell them to pack sand when their 6.0L pukes.

[StrangeEngine]

Valve covers, not the heads on an LB7. The LLY valve covers have a relief in them for the injectors.

That makes a hell of a lot more sense, but then why is it a $4000 job? Valve covers should be comparatively easy.

- Mark

[jbplock]

...there is system dirt that erodes the injector internal parts...

Interesting ... is this system dirt self induced inside the fuel injection system after the high pressure pump? from cavitation erosion?

[Gnostic_1973]

Take a look at the tank is has an open vent. The particle sizes I am talking about are in the 2-4 micron range.

[dieseldummy]

So I guess that the stock filter does nothing then... If GM really wanted to step up to the plate they would actually fix the injector problem instead of extending the warrenty and then trying to give people the shaft over fuel quality and all the BS they have come up with. If there are particles in the injection system that destroy the injectors why is the high pressure pump spared? It has to maintane close tolerences in order to make 23,000+ psi...

[Gnostic_1973]

The stock filter does do a good job (4 microns) and the injector problem is fixed, so I guess GM answered all your troubles...thanks for being loyal. You could always buy a Ford or Cummins diesel, which with the Ford you get a piece of **** and with the Cummins you get the same Bosch common rail system execpt a previous generation version.

You make it sound like they are out to put the screws to all of their customers, which means you have no idea how difficult it is to make a diesel engine that will survive the abuse that the typical owner subjects them to daily. Diesel engines of today (and the future) are far more complex than ever before and with that comes extreme engineering difficulties...have faith in the General that they are making the best product available.

[dieseldummy]

Well, I guess you have all the answers... You say the open tank vent lets in particles that destroy the injectors. I question how the injectors fail with the particles and the CP3 doesn't? Both parts of the system operate with simlar presicion.

If the injector problem is fixed then why are there guys that have had multiple sets of injectors under warrenty and are still going back for more? Rumor has it that GM/Bosch is testing a new prototype injector and it has failed too... Get real man, this injector ordeal has given Dmax a bad name.

While I'm certainly not a fan of the Powerstroke diesels I wouldn't go so far as say the are a POS. The 7.3 has proven to be very reliable with only minor problems. The 6.0 had a few more issues, but there are alot of them running around out there with no problems. 6.4TT... not enough out there yet to say.

Cummins... I think that their track record speeks for its self there.

I guess just because someone doesn't agree with your point of view they don't know jack? I am fully aware what it take to make a diesel engine meet emissions standards, have competitive power levels, last for 150,000+ miles, and get decent fuel milage. Thanks to common rail fuel injection this is alot easier now...

With reports of people being denied extended injector coverage due to "bad" fuel, aftermarket mods, and a number of other bogus claims it's hard not to think that GM is trying to weasle its self out of this...

So you work for the General then Gnostic_1973?

[Gnostic_1973]

I am not saying your opinion is wrong, I am saying mine is right which is exactly why it is MY opinion. We are all entitled to our opinions and we won't all agree. I think that there are many obstacles our there that some people don't see. I have worked for Honda R&D, International Truck & Engine, and for the maker of the Duramax. I am a car guy and I love engines. I do not drive a diesel because I cannot justify a Duramax because I don't tow, or "work" with my vehicle, but if I did I would choose a GMC w/ Duramax. I have seen all (3) engines in pieces and my opinion is that if you have a Duramax/Allison combo powering your vehicle...there is none better on the market. Period!

[Gnostic_1973]

Comes with an optional fire starter for the camper types...

See thermal event at the bottom of this page:

http://www.forddoctorsdts.com/

[chrisinkanata]

I guess then that leads me to the next logical step....are the re-manunfactured injectors installed in my truck a couple of years ago any better than the original ones. What about ones I would have installed today? Are they better? I can say that I now have about half as much again the mileage on these ones than on the originals, but these have had the benefits of superior filtration for their whole life. Having neglected to plug the truck in over this winter a few times in the -27C temp range, I find that it still starts like the day it was new. Sounds like a bag of hammers for a minute or so, but it goes. Hard starting was the first symptom of the original injector failure.

In researching this online, it seems to me there are very limited options for replacing them when they fail. It does not appear that there are multiple sources. That may change over time. Obviously, when still under warranty, you go to the dealer, but I'm driving my truck into the ground so to speak, so I suspect that I'll have to do them on my own dime at some point in the future. Having been an automotive tech in a previous life, I suspect I can muddle my way through the job, but even at that, the cost is huge.

I would not be surprised to hear that all the re-manufacturing is done by one company. I am fully cognizant of the extreme conditions that the injectors live in and all that, but for that kind of coin, it would be nice for them to come with a degree of certainty.

[jbplock]

Take a look at the tank is has an open vent. The particle sizes I am talking about are in the 2-4 micron range.
A few years back a number of us did ISO particle count tests on our fuel ... see Fuel Test Results (http://home.stny.rr.com/jbplock/ISO/OC_Dmax.pdf) ... We know the fuel contains harmful particles in the 2-4 micron range and the tank vent is not the only source .. These particles are in the fuel before it's pumped in to the tank.. From the actual test results many of us concluded the OE filter was inadequate so we added high efficiency (98-99%) 2 micron filters.. This was also prior to the GM redesign of the OE filter to double the filter layers ...

:)

[Duramaster]

I'm still stuck on why someone would think that the heads would have to be removed to replace the injectors?!!!!!!!!!!!!! Must be bad "ARCHIVES!" I think that strange even owns a DMAX. Correct?

As far as the filter goes....... It's really funny that the 5.2 and the 7.8 DMAX engines don't have the injector problems that the LB7 or even the LLY have/ had. Here is one theory and don't take get too mad but the fact is is that the V-8 DMAX uses DUMB OLD BOSCH :mad: injectors and the 5.2 and 7.8 use DENSO injectors. Call me crazy, but I think that the Japanese got it right this time!!!:cool:

As far as change interval goes, After a hundred thousand miles of the injectors slamming shut, I would expect to have to perform some kind of "tune-up" maintenance on the engine. There isn't any valve adjust interval listed either, but in the case of the last truck that I worked on (184,000 miles and the original injectors) the valves were definitely in need of an adjustment!

[OC_DMAX]

With regard to injector failure, I seem to remember two causes being mentioned in the letter that I received from GM. (And this is going from memory!!)

1) Ball Seat Erosion - would imply that the filtration was not sufficient enough to make the injectors last the "original" design interval of 200K. This is supported by the fact that GM redesigned the OEM fuel filter to go to a dual pleat arrangement. Thus, those of us who have been running supplemental filters had the right concept.

2) Cracked Injector Bodies - the would imply that the injector body design or metal used or the treatment of the metal was defective. My assumption is that GM (through its supplier Bosch) has either redesigned the defective part or changed the material used in the newer injectors. There is probably nothing anyone could have done about this type of failure. Strictly a defective design. Doesn't matter how clean the fuel is.

My only issue with the GM 7yr/200K warranty is that some of us are low mileage users. I EXPECTED my injectors to last 200K miles per the design hype from GM when they released the engine. IN MY OPINION, they should warrant the injectors for 200K miles and be done with it.

It will be interesting over the next couple of years to see what happens when the 7 year portion of the injector warranty expires. At this point, very few people have had to pay the $3K-$4K to replace the injectors. I believe that GM will have to face a large number of PISSED OFF consumers when they are confronted with the bill. I hope they are still researching and improving the injectors. The right thing to do is to replace the injectors as they fail for the labor cost only ($1K) for units under 200K miles. It will be interesting to see what happens and how GM handles it.

[StrangeEngine]

I'm still stuck on why someone would think that the heads would have to be removed to replace the injectors?!!!!!!!!!!!!! Must be bad "ARCHIVES!" I think that strange even owns a DMAX. Correct?

I do, but I mis-remembered what I'd read here in the past. My bad.

However, if it's a only a valve-cover removal, why the hell is an injector job $4K and take a couple of days?

- Mark

[Duramaster]

Coming from lots of experience, the injectors are ordered against the VIN number from GM. The injectors usually take two days to arrive from the VENDOR that is unless they go on "INTERGALCTIC BACK ORDER!!" That happened not too long ago and at that time I had three trucks down for approx. three weeks!! ISUZU has tight control over the injectors at this time. Hopefully GM doesn't do with the injectors like they do with the 6.5 diesel injection pumps (call and talk to GM TAC and give them a bunch of diagnostic info). After the injectors arrive, the job then pays 8 hours. Sometime they can be done in 5 - 6 hours and then sometimes they take longer depending on how after market garbage is on the truck!!

Now don't take offense to the garbage comment, just remember that if you were in my shoes you would be saying the same thing (stupid 6" lift kit, brush gaurd, 15k Lb winch, belt driven PTO, etc.)

I personally like to keep the truck overnight after the job is done so that I can check how well the truck starts when cold (another day).:cool:

[siggy]

<<<<<"INTERGALCTIC BACK ORDER!!">>>>>

Ha! That's a good line, at least for my situation. My LB7 is due to get 8 injectors tomorrow.... which is a mere 5 weeks after the diagnosis and order being placed for the injectors. I even took the time to speak to the service dept about availability, prior to letting them do the testing, and was assured that they were able to do a special *expedite* on the parts orders and 2-3 days would be the absolute max for waiting. Trying to look at the brighter side, maybe the freeze on shipping out injectors had to do with a revision/update/etc. implementation. Doubt it, but a possibility?

[Duramaster]

The last few jobs that I have done, the injectors were actually NEW ones and not actually REMAN injectors like the box label states. Pretty cool I think!:cool:

[More Power]

Originally Posted by Duramaster
I'm still stuck on why someone would think that the heads would have to be removed to replace the injectors?!!!!!!!!!!!!! Must be bad "ARCHIVES!" I think that strange even owns a DMAX. Correct?

What's your experience with dislodged injector cups during an injector replacement, which then result in compression/coolant leaks? Do any GM techs reseal the cups as a consequence of replacing injectors?

Thanks for contributing here in the board!

Jim

[Duramaster]

Occasionally the injector sleeves do pull out with the injectors when there are severe carbon build up on the tips and in the tube portion of the sleeve. So here is what GM states in SI:

"If the fuel injector sleeve was pulled from the cylinder head when removing the injector(s), refer to Fuel Injector Sleeve Replacement in Engine Mechanical - 6.6L."

Important: Inspect the seating surface on the fuel injector sleeve and the fuel injector sleeve bore in the cylinder head for debris or damage. If the injector sleeve bore is damaged, the cylinder head may need to be replaced.





Clean the fuel injector sleeve lower sealing area (1) and the sleeve bore with GM P/N 12377981, (Canadian P/N 10953463), or equivalent.



Lubricate and install NEW O-rings (1) onto the fuel injector sleeve (2).



Install the fuel injector sleeve onto J 45910 .



Apply adhesive GM P/N 12345493, (Canadian P/N 10953488), or equivalent to the fuel injector sleeve lower sealing area (1).



Install the fuel injector sleeve with J 45910 into the cylinder head.



Lightly tap on J 45910 with a hammer to install and seat the fuel injector sleeve.
Remove J 45910 from the fuel injector sleeve.
Install the fuel injector(s). Refer to Fuel Injector Replacement in Engine Controls - 6.6L.
Fill the cooling system. Refer to Draining and Filling Cooling System in Engine Cooling.
--------------------------------------------------------------------------

The adhesive is nothing more than RED LOCKTITE and it is applied at the tapered end of the sleeve where it meets the tapered seat of the head. My service manager actually wants me to use GREEN locktite!!!

I replace the two o rings at the top of the sleeve also. I have never had a leak sleeve leak after repairs:cool:

[JohnC]

OK, why different part numbers in Canada? Imperial? Metric? Celcius?

[siggy]

Got her back from the dealership today, all 8 injectors replaced. No charge to me, not even a $100 deductable, at 115K+ miles. Not sure if they replaced any sleeves, if so they were not so listed on the repair order as 'sleeve'. $1382 Labor, $2242 parts, grand total $3624.61 inclusive of the oil change. Hope all is well for another 100K or so. Any signs/areas to keep an eye on after injector replacement?

[Duramaster]

The sleeves are stainless steel and rarely need replacing unless there is extreme corrosion on the sleeve. But in that case, I'm sure the head would be junk also. I had one not too long ago that had a severe electrolosis problem. I replaced both of the heads because the seat for the sleeves was eroded away.

[Duramaster]

As far as the different sealants, I don't know. I live in the states so I use the sealants that are available to me. Like I said, the sealant is RED lock tite and as far as the cleaner, I use laquer.:cool:

[papa bear]

Got her back from the dealership today, all 8 injectors replaced. ...............

Any signs/areas to keep an eye on after injector replacement?


What are the symptoms of bads injectors?

I have 75k miles on a '02..

[DmaxMaverick]

Welcome to the Forums, Marty!

Several things in combination can suggest injector failure. Some things are outright indicators, and others may be related.

In no particular order:

Fuel in crankcase
Hard or no starting
White/gray smoke
Knock at idle
Rough/surging idle
Missing
Pre-ignition knock at startup (one ping right before it starts)
Chugging/knocking at moderate throttle
Fuel economy drop
Strong exhaust odor

There are others, but require a Tech II scan tool or extensive testing. Even with all the objective symptoms, some dealers still won't replace them w/o more testing.

[papa bear]

well I got the knock at both idle and moderate speeds. It isn't as bad as a late 90's cummins engine, but it's definitely noisier than a new engine. I also have a drop in fuel economy. Changed oil two weeks ago, seemed a little thin, but not real bad - quantity seemed about right....

I had it at the dealer a couple months ago to verify the neutral safety switch was bad. Couldn't bring myself to paying $400 for GMC fix (second time!) when the same part is available down the road at the Allison shop for $50. Dealer agreed, and let me off for $50 charge on the diagnostic. At that time he didn't say anything about injector codes though....

Something isn't right though...

[DmaxMaverick]

More often than not, there will be no codes.

If all you have is a knock, try a good additive with cetane improver. It will either clear it up, get worse or do nothing (real helpful, huh?). In the absence of any other symptoms, it isn't likely the dealer will do anything unless the knock is real bad. If your injectors are original, the knock could be an early sign of what is to come. Watch for increasing oil level and smoke.

[Mark Meyers]

I have a 2002 Duramax LB7 with only 57,800 miles on it but because it is now 8 years old GM said they would not replace the injectors that the dealer has diagnossed as failed. The dealer wants $4,500 to fix and that is not going to happen. So does anyone know if it is possible to buy new not "reman" injectors? If so where? Are the new injectors improved? Does anyone know if there are any unhappy owners of 8 and 9 year old trucks going after GM for repairs? I never got any injectors and I have heard of people receiving two and three sets. does not seam resonable does it? Any sugestion would be appreciated, I am not looking forward to doing this myself but I have done bigger and worse so I will get through it. Thanks Mark.

[oilburnertoo]

I have a 2002 Duramax LB7 with only 57,800 miles on it but because it is now 8 years old GM said they would not replace the injectors that the dealer has diagnossed as failed. The dealer wants $4,500 to fix and that is not going to happen. So does anyone know if it is possible to buy new not "reman" injectors? If so where? Are the new injectors improved? Does anyone know if there are any unhappy owners of 8 and 9 year old trucks going after GM for repairs? I never got any injectors and I have heard of people receiving two and three sets. does not seam resonable does it? Any sugestion would be appreciated, I am not looking forward to doing this myself but I have done bigger and worse so I will get through it. Thanks Mark.


Now that is a f**kin shame, GM should step up to the plate on this!!!!!
I can almost replace the 6.5L engine in my truck myself for that price tag!!
I guess I will stop looking for a good used D-Max to upgrade my old ride.

[NutNbutGMC]

Now that is a f**kin shame, GM should step up to the plate on this!!!!!
I can almost replace the 6.5L engine in my truck myself for that price tag!!
I guess I will stop looking for a good used D-Max to upgrade my old ride.
You are part owner of GM. Step up at the voting polls (the plate) this coming November. :) Makes me mad too...

With this forum saturated beyond belief (for several years) about this issue, why would you just now decide this about your upgrade?


Just curious, with all due respect.

[jbplock]

.. So does anyone know if it is possible to buy new not "reman" injectors? If so where? Are the new injectors improved?.

Mark,

New LB7 Bosch injectors are a available but they are not cheap - over $500 each .. Here's one source http://www.hdiesel.com/productdetails.asp?cat=Injectors&ID=140&pID=597

The latest GM remans are improved and reports indicate they are holding up well - I have set in my 03 (replaced at 88k) and the truck is running better than new. My out-of pocket cost for a set of 8 GM remans from www.partszoneonline.com (http://www.partszoneonline.com) was $213 each (including return shipping for the cores). If you're handy with a wrench you can do the job your self and there is an excellent How-To article in the DieselPage Members Area that walks you through the procedure step-by-step. (click on the following link)
http://www.thedieselpage.com/members/duramax/LB7InjectorReplacementc.htm

:)