LB7 injector replacement

[stephenb]

My 2002 Duramax has diesel in the oil and rough idle at 112,000 miles. Dealer said needs injectors and that the injector pump gate valve is stuck open. they want about 6-8 k to fix including the pump and are offering $5500 as is for the truck. Is it worth repairing?

Looking at doing the job myself:

1. where to get and what injectors to use
2. what else to replace while apart
3. does the pump gate valve make sense; i have not read anything about this

Dont mean to beat the horse on this but would appreciate some guidance

[Kennedy]

Injection pump gate valve?

It could be that the regulator has failed. This will cause an erratic, lopey, crackly idle as the pressure can max out and make it chop the injector pulses.

With 112k on the clock I'd sure think it was worth fixing.

As for the fuel in oil most likely the injectors.

Hard to diagnose over the web or phone.

I had a customer/friend (shop) order injectors for a fuel in oil case. Pretty much always the injectors. Not in this case. Did a pump and same thing.

Turned out to be a blocked return in the tank sender causing excessive pressure and then a leak.

[stephenb]

Thanks for reply:

I picked truck up today and diagnosis read;
Fuel injectors bleeding down
Fuel pressure regulator sticking
Drove home and diesel/oil on ground

Definitely a lopey idle.

[Kennedy]

Lopey like rolling smooth/oscillating, or lopey crackly and rough? Sounds like it's sticking high and running at 23,000 psi all the time.

I'd be inclined to try a regulator first and see what happens.

Drain the crankcase and refill first if it's filling up. You may have further problems, but first thing's first get the pressure regulated.

[stephenb]

Rough like a gas engine with plug disconnected

RPMs not fluctuating

[Kennedy]

Sounds like not regulating. Three possibilities:

1) Regulator
2) wiring
3) ECM

Most likely regulator, but I have seen an ECM go bad as well. Semi locally we had a medium duty that did this. I took along an ECM swapped it and no change. Ended up being the regulator which he had his mechanic swap and problem solved.

[More Power]

I agree with Kennedy, once the other items have been eliminated, I'd just replace the injectors and regulator together. A truck with just 112K is definitely worth the effort and expense. Jim

[stephenb]

Update:
Replaced the fuel pressure regulator over weekend; drained over 6 gallons of diesel/oil mix and replaced with 2.5 gallons of oil.

I am Cautiously optimistic; The idle is normal and smooth and after ten mile road trip at high speeds no diesel in the oil.

Plan on driving a bit longer and further and rechecking the oil level.

Thanks very much to your replies; very appreciated.

[Kennedy]

Sounds good keep us posted. The fuel had to be coming from somewhere, but since there was a regulator issue and the rail psi was then running out of control it could have had too much volume/pressure in the return side.

[SoTxPollock]

I had one injector set replacement, and thought it would be the last. Can't believe that is all they offered you for the truck. I've got written confirmation of $11,000 for trading my 02 if I want to. Anyway, my truck is now starting to smoke at idle, but not white like it did before needing the injectors replaced, it's has a slight blue tint to the smoke. Surely the rings haven't started to go already. Any idea's? It still hauls good if you jump on it. Only about 40,000 miles on the replacement injectors. Could the fuel suppliers be adding more oil than they did before? I think around here most of the diesel has somewhere between 10 and 15% biodiesel. I just don't know what to think.

[stephenb]

Diesel is still making its way into my oil after the FPR replacement; however the rate at wich the oil level is increasing has slowed considerably. Idle problem is corrected.

Never saw such clean oil in my truck; I guess the diesel fuel cleans the engine.

Now to determine what is leaking, what to replace, and what parts to use.

Alot of postings on this topic out there, but it looks like there is not a fix that eliminates the problem. Also seems like alot of diagnostics and interpretation to try and figure out what is actually leaky. I saw a youtube of a guy running the engine with the heads off and fuel spraying out of the leak.

What are your thought and suggestions in regard to:

1. Bosch injectors (reman or new or someone elses)

2. New Injector line sets? Or clean the ones I have?

3. Cleaning the fuel system prior to starting the replacement/repair per the posted procedure using the Gm cleaner and disconnecting the quick connects at the rear of the engine.

4. Adjusting the valve clearance while heads are off?

5.Sealing fuel line to injector with RTV per Merchant tech notes

6. Any other "tricks" advice of what to do while heads are off.

7. Any way to hydro the high pressure fuel lines to verify/find the leaks with the engine heads off?

Thanks for the help!

[rapidoxidationman]

First a point of correct terminology: The head of the engine contains the valve train, injectors, glow plugs, etc and is the roof of the piston cylinders. Without the heads installed an engine is just a paperweight. I'm thinking you mean valve covers when you say heads in your post below?


Diesel is still making its way into my oil after the FPR replacement; however the rate at wich the oil level is increasing has slowed considerably. Idle problem is corrected.

Never saw such clean oil in my truck; I guess the diesel fuel cleans the engine.

Now to determine what is leaking, what to replace, and what parts to use.

Alot of postings on this topic out there, but it looks like there is not a fix that eliminates the problem. Also seems like alot of diagnostics and interpretation to try and figure out what is actually leaky. I saw a youtube of a guy running the engine with the heads off and fuel spraying out of the leak. With the heads off? Do you mean the valve covers? That would be an interesting video to see. Got a link? I'd think oil would also be spraying everywhere...

What are your thought and suggestions in regard to:

1. Bosch injectors (reman or new or someone elses) Remans are what you'll get. Don't get cheap ones, they'll be more expensive than good ones very quickly. There are vendors on this site that can get you what you need.

2. New Injector line sets? Or clean the ones I have? popular thinking is to replace the lines since you're in there and getting them truly clean and particle free to where they won't clog your fresh injectors with rust isn't easy.

3. Cleaning the fuel system prior to starting the replacement/repair per the posted procedure using the Gm cleaner and disconnecting the quick connects at the rear of the engine. Clean. Clean. Clean again. Then make sure everything is clean.

4. Adjusting the valve clearance while heads are off? While the valve covers are off? Can't hurt.

5.Sealing fuel line to injector with RTV per Merchant tech notes A properly installed fuel line has no need for sealant and a stray bit of sealant will ruin your day - and your spray pattern on a fresh injector.

6. Any other "tricks" advice of what to do while heads are off. Again, heads? Or Valve covers?

7. Any way to hydro the high pressure fuel lines to verify/find the leaks with the engine heads off?

Thanks for the help!

[Kennedy]

Probably not a bad idea to start with the injectors. This way all of the return seals under the covers are checked as well.

New supply lines are a must in my opinion.

NO sealant on the line to nut. Any imperfection will let it breathe and take on/trap moisture potentially.

Once you have the injectors taken care of (most common issue on LB7 and likely close to due anyhow) if the problem persists it can really only be one thing: the CP3 pump.

[rapidoxidationman]

What does CP3 stand for? I (think I) know it is the high pressure pump, but why the CP3 designation?

[stephenb]

Thanks for the reply's

Yes valve covers is what I meant

To see video of Duramax running with valve covers off check youtube.com and search "Duramax LB7 fuel injector leak without valve covers"

[stephenb]

Anyone know anything about what injectors direct is selling as refurbished injectors and fuel lines?

I am getting ready to replace both and want to get the correct parts; please let me know where to get the best value. I am also looking at there replacement kit.

Thanks

[Kennedy]

If you want to do a covers off test I'd recommend adding tracer dye to the fuel and check with a black light.

I really see no way short of some sort of a full chemical boil to remove the rust on the lines. These things are too darn expensive and labor intensive to do twice. That's why we use new lines and top quality injectors.

[stephenb]

Thanks Kennedy;

Just started removing valve covers; you are right on the money.

Once you pull off the lines going from the common rail to each injector you will see how dirty they are. I plan on new lines and injectors.

Ready to pull passenger side valve cover......

will post some pics and keep you up to date on progress.

I have been shopping parts....