Yet another injector question...

[Vetman7]

I have a 2002 LB7, with 143,000 miles. I replaced the injectors the first time at 80,000 (Warranty replacement) and am assuming GM used rebuilt injectors. Now after another 50k I'm getting black smoke at the tailpipe at idle. No increase in oil level, or fuel smell in oil.



It's important to note that I have a Kennedy MegaFilter and have been using a mix of FPPF and Cetane booster since the truck was new. I'm puzzled WHY I need injectors again, as I thought particulates in the fuel was the culprit...


Anyway, here are my questions:
1.) I was told I could buy some time before injector replacement by using additional additives. The recommendation was to use Hot Shot Diesel Extreme. Any better ideas, or do additives at this point do nothing?


2.) I'd like to do the injector replacement myself, but need info on special tools for injector and cup removal and whether it's necessary to remove injector cups, or not...



3.) I figured I'd buy injectors from Kennedy Diesel, but are the tools available there as well as all the extra parts (lines, o-rings, gaskets, etc?)



Appreciate any help you can provide...

[Kennedy]

There is not a lot of need for special tools to do these. 5mm hex driver bits for the rocker cover screws and things like that. We don't use any injector pullers so as long as the cups stay in things go pretty smoothly.

I have been running SAC type nozzles on my LB7 for probably 10 years now. In recent years they have been introduced for the street market as a cure for the blue smoke at idle. These were 45% over so I did custom programming to tame them down. Coming very shortly will be a SAC nozzle with stock delivery flow. They should not need any programming, but I do suspect that they will benefit from a good tune even more than the std VCO nozzle.

[Vetman7]

Thanks John. I'm actually running an EDGE HOT tune that I got from you. Will that work with the SAC nozzles or do I also need a reprogram?


Of course, all of this adds lots of expense, so back to my question about buying some time by using additives to restore some function to the injectors. Any chance this will help? I did the Injector Balance Test and found Injector #7 with a value of -6.8 to -7.0. All other injectors were within -2.5 to +2.5.



Thanks again for your help...

[Kennedy]

As soon as I poo-poo the Hail Mary approach of dumping in a mega dose of some wiz bang miracle cure someone reports complete success That said, the VCO style nozzle is subject to needle steer and the blue smoke has been documented many times over as a 40-50k repeat with the late production injectors.

SAC 00 should be pure stock delivery so no absolute need for tuning, but I do have some tweaks that tend to improve operation. At that point I would move on from the Edge.

[More Power]

I have a 2002 LB7, with 143,000 miles.

Anyway, here are my questions:
1.) I was told I could buy some time before injector replacement by using additional additives. The recommendation was to use Hot Shot Diesel Extreme. Any better ideas, or do additives at this point do nothing?

2.) I'd like to do the injector replacement myself, but need info on special tools for injector and cup removal and whether it's necessary to remove injector cups, or not...

Appreciate any help you can provide...

John covered your other questions well enough, so I clipped your original post so I could spend a little time with the above two questions...

We've been doing this diesel thing for a long time, and the question concerning the benefits of fuel treatment has been hashed and re-hashed many-many times. Here's what I think... Personally, I believe fuel treatment is worthwhile IF the treatment includes a cetane improver in the list of ingredients. Large fleet tests have proven that fuel economy is increased enough to pay for the cost of treatment. What's not easily proven is whether a treatment extends the life of fuel injection components... There's just no way to know for absolute sure - no positive proof either way. Can a fuel treatment clean parts of the fuel system, removing varnish or other stuff that can negatively affect injector performance? Maybe, but proof that shows it extends injector life is really hard to come by. A couple of anecdotal reports...

Industrial Injection dot com has been offering "screw-in" LB7 injector cups for some time now. I wrote about screw-in cups as a "I wish this existed" product many years ago. Now it's a reality. They're not cheap, but it would remove the angst over whether that excess pressure in the cooling system is due to a cup seal leak or a head gasket leak. You'd be surprised/horrified to read as many reports as I have from everyday LB7 owners about over-pressurized cooling systems in the days/weeks/months following an injector replacement in these LB7s - too many to be coincidence.

I've spoken to many long time Duramax mechanics through the years, both GM certified and independent shop mechanics about this very issue (cup seal leaks when/after changing injectors). About a third of them reseal every cup that had its injector removed. The rest don't reseal any of them unless they "see" the cup move when removing the injector.

I'm hoping to do a head gasket and Industrial Injection cup install later this summer. I want the engine to be as trustworthy as it was when bought new. Everything else in the truck is like-new...

My thoughts...

Jim

[Vetman7]

Hi Jim,


Thanks, I appreciate your reply. I've tried the additives now for about 5k miles, and things are just getting worse (lots of blue smoke and very rough idle). Of course, you'll note from my original post that I've been running a cetane improver since day 1. So clearly that didn't prevent the injector failure issue. Since the injectors were warranty replaced initially by GM, I'll assume they replaced with the same, failure prone type originally used, -which now are also bad!. Since it seems changing injectors is definitely in my future, I'll look for an aftermarket set with better design (any recommendations??). Unfortunately, its a complex enough job that I don't want to do it twice because the cup seals are leaking. Do you recommend replacing all cups with the screw-in style and any idea of the cost? When I pull the injectors, is it obvious if the cups remain intact? Or can they leak even if all appears to be good? Appreciate any additional thoughts...

[More Power]

Hi Jim,


Thanks, I appreciate your reply. I've tried the additives now for about 5k miles, and things are just getting worse (lots of blue smoke and very rough idle). Of course, you'll note from my original post that I've been running a cetane improver since day 1. So clearly that didn't prevent the injector failure issue. Since the injectors were warranty replaced initially by GM, I'll assume they replaced with the same, failure prone type originally used, -which now are also bad!. Since it seems changing injectors is definitely in my future, I'll look for an aftermarket set with better design (any recommendations??). Unfortunately, its a complex enough job that I don't want to do it twice because the cup seals are leaking. Do you recommend replacing all cups with the screw-in style and any idea of the cost? When I pull the injectors, is it obvious if the cups remain intact? Or can they leak even if all appears to be good? Appreciate any additional thoughts...

John (kennedydiesel.com) has a lot riding on the reliability of the injectors he sells. He may be exposed more than most fuel injection component suppliers because his sales effort has been concentrated on the web. The web doesn't take prisoners. I'd trust him if you're a do-it-yourselfer.

If you have someone else replace your injectors, I'd pin my hopes on them to select the injectors because they simply have to offer a warranty. Still, I'd do a little research before trusting my truck to an unknown (remember the web doesn't take prisoners).

I think we're in a better place, regarding injector durability/reliability, than we were some years ago. Just stay away from cheap knock-off imported parts.

[Kennedy]

Hi Jim,


Thanks, I appreciate your reply. I've tried the additives now for about 5k miles, and things are just getting worse (lots of blue smoke and very rough idle). Of course, you'll note from my original post that I've been running a cetane improver since day 1. So clearly that didn't prevent the injector failure issue. Since the injectors were warranty replaced initially by GM, I'll assume they replaced with the same, failure prone type originally used, -which now are also bad!. Since it seems changing injectors is definitely in my future, I'll look for an aftermarket set with better design (any recommendations??). Unfortunately, its a complex enough job that I don't want to do it twice because the cup seals are leaking. Do you recommend replacing all cups with the screw-in style and any idea of the cost? When I pull the injectors, is it obvious if the cups remain intact? Or can they leak even if all appears to be good? Appreciate any additional thoughts...

The SAC-00 injectors, a set of new OE supply lines a set of return line end seals, and a tube of ultra gray are the main components that you need.

Secondarily a pair of thermostats because you are already in there. Lift pump, secondary filtration, and FPPF Total Power fuel treatment for protection.

We stock all of the above most of the time.



Leave the cups alone. The only cup issues that I have seen is guys trying to wish away a head gasket issue or those that improperly sealed them after popping out during an injector job. I run the std cups in my 2002 at 80psi boost.

[Vetman7]

Well, from now on, I'll take John Kennedy's advice to heart. The fuel treatments I asked about a few months ago (as an alternative to injector replacement) clearly didn't do anything except waste my money! I finally gave up and am ready to order injectors. I plan to get the SAC 00 type because the VCO seem to require replacement every 50-70k miles.


Now for a follow up question... Once I drain the coolant and tear all the bolt-ons off the top of the engine, is that also the time to consider replacing the fuel pump? It has not given me any sign of failure, but replacing now could avoid a repeat tear-down later. Any thoughts?


Thanks in advance for some very good advice on this forum!

[More Power]

Personally, I'd not change it unless tests reveal a problem. A Tech II scan tool can exercise the pump through its range of pressures. But, I get your concern about replacing things when the engine's top-end has been disassembled already... It's tempting. I'm sure the shops would argue for it, but then there are stories about "over-selling" shops...

[Kennedy]

The CP3 pump seems to run about forever when treated with respect.

At the risk of being overly repetitive: do the thermostats right away while in there. We leave the hot pipe in the thermostat cover and remove as an assembly to avoid issues with the oring rolling or pinching etc.

[More Power]

....We leave the hot pipe in the thermostat cover and remove as an assembly to avoid issues with the oring rolling or pinching etc.

Good tip!

Jim

[rapidoxidationman]

Good tip!

Jim

Indeed. A month or so ago I changed the water pump on my truck. In and out in less than 5 hours (thanks to the proper tools to hold the engine, break loose the crank balancer bolt, and break the fan clutch bolt loose). Filled with dexcool and... WTF! where's all the coolant coming from? I had put fresh o-rings everywhere I could, but the ring right where Kennedy specified had rolled out of place upon assembly. OK, tore things down to where I could swap it for another, well lubed (fortunately, I had an extra). Reassemble, fill with coolant, and darned if it hadn't done it again. It took a couple more tries before I finally went to the parts store and got a slightly oversized ring and stuffed it in. Problem solved. Maybe this is why the book time is closer to 9 hours...

[More Power]

Indeed. A month or so ago I changed the water pump on my truck. In and out in less than 5 hours (thanks to the proper tools to hold the engine, break loose the crank balancer bolt, and break the fan clutch bolt loose). Filled with dexcool and... WTF! where's all the coolant coming from? I had put fresh o-rings everywhere I could, but the ring right where Kennedy specified had rolled out of place upon assembly. OK, tore things down to where I could swap it for another, well lubed (fortunately, I had an extra). Reassemble, fill with coolant, and darned if it hadn't done it again. It took a couple more tries before I finally went to the parts store and got a slightly oversized ring and stuffed it in. Problem solved. Maybe this is why the book time is closer to 9 hours...

I watched a mechanic change a water pump a few years ago. He lubed the wpump bypass pipe o-ring with Dex-Cool and then carefully worked the pipe into the crossover, stopping halfway to check to ensure the o-ring hadn't slipped out of position. Jim

[Kennedy]

I watched a mechanic change a water pump a few years ago. He lubed the wpump bypass pipe o-ring with Dex-Cool and then carefully worked the pipe into the crossover, stopping halfway to check to ensure the o-ring hadn't slipped out of position. Jim

Seriously? Dex Cool? The stuff that corrodes the living crap out of aluminum in the presence of oxygen?

Back in the day I pulled the upper hose from the stat housing on my old 96 with Dex in the system. Reinstalled without rinsing. Never again. Next time apart the water outlet was all pitted to hell beneath the hose and outward of the seal of the clamp. I now make a conscious effort to make sure that any remnant of Dex is rinsed clear to avoid this. Still a believer in Dex, just be sure the system is sealed.

[Vetman7]

I decided to pull the injectors out before ordering the new set. Then I'm ready to immediately return for the core charge once I receive the new ones. Obviously the truck isn't going anywhere while I wait, but that's OK.



So, I started pulling injectors... I used the round end of an air chisel to fit in the hole of the hold down bracket and moved the injector side-to-side and gently pried under the bracket to lift. Well, the first three injectors came right out.. along with the cups! I set them on the bench and needed two flat blade screwdrivers to pry the cup off the injector. I found the o-rings on the injectors had rolled out of the grooves and the entire body of the injector and inside the cup was caked with carbon. It seems all that crud cemented the cup to the injector, which seems to explain why the assembly came out rather than just the injector.



I thought as part of the install, that red loctite was supposed to be coated around the bottom of the cup where it seats in the head, but the cups were absolutely clean on the outside when I pulled them out. I was surprised, because the last injector replacement was done by GM under the original warranty. Am I right about using the loctite on the bottom of the cup?



I need some advice on the best way to re-install the cups and injectors. Right now I'm thinking that I need to install the injectors into the cups (on the bench), then coat the cup with loctite at the bottom and re-install the assembly into the head, using the hold-down bracket to seat the assembly. If I torque the injector into place that should hold the cup properly while the loctite dries.


Sound right or is there abetter way? Thanks again for all the good advice!

[rapidoxidationman]

I don't believe there's anything like loctite to keep the cups in place.

AlldataDIY is a cheap subscription and will tell you everything you need to know (torque values, special tools, install/disassemble procedures, etc.). I've easily paid for many years of the service in not having to bring my trucks and cars to a mechanic...

[Kennedy]

For removal we run an old line back on the injector to use as a handle to twist and then a sacrificial return line screw gets run in to use as a pry point. Rotating wiggle back and forth with a steady pry typically gets them

I think I said way back the cups almost never come out unless an oring gets rolled. Sounds like yours were close to releasing. Often they get baked in and you almost have to heat the cup with a torch to remove and pretty much make junk. We generally leave stuck cups on the injector core and put a different one in the engine. I'd hate to see what would happen if the cups were screwed in and an oring rolled. Not sure how you'd get that injector out?



Loctite the tip of the cup with red high strength. You will not see this loctite again It does it's job but disappears. Put the cup in place then the injector and torque down immediately. Nice to leave set 24hrs before filling coolant.

[Vetman7]

I finished the new SAC00 injector installation (after all the above discussion several months ago) and now have 4000 miles on the new injectors. Initially, all of the balance rates were -0.5 to +0.5, with one exception, Cyl #6, which came in at +3.7. Still, no reason to worry. Now, after 4k miles, I noticed a little extra diesel clatter around 1500 rpm, so decided to recheck balance rates. All were within the -4 to +4 mm3 guideline, except for Cyl #6, which is now at +14. I contacted the vendor of the injectors and they agreed to replace the one injector.



I have heard horror stories about injectors that are stuck open burning holes in pistons or trashing exhaust valves. Without pulling the head can I assess if there's been any damage?

[Vetman7]

With an injector balance rate of +14, essentially the injector seems to be stuck open. But WHERE is the extra fuel going? No smoke at the tailpipe and no extra "volume" in the oil. Or does the injector have a high return rate, so the fuel is never making it into the engine?