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It's often amazing how things are changed for one reason or the other then marketed as the best thing since sliced bread.....here's something I learned today from a GM source. Try this on for size.


The '04 LLY models have to comply with new EPA Regs. This mean Cat, ER and PCV to recycle the crankcase fumes and clean up the emissions. To do this they have to close the crankcase breather hose we all know and love. Now we should have a closed system right!


So fuel return lines are inside the valve covers and injectors can leak into the crankcase in the LB7 right. Well if you have a closed system with fuel leaking into the crankcase and those fumes recycled though the injection system, you no longer have throttle control and can have a RUNAWAY engine! Nice Huh, so to solve the Runaway issue the return line are outside the valve covers and injectors are clear of the crankcase.....problem solved.


So not so much that we wanted this stuff anyway as an improvement, like it's being marketed, but to allow for the ERG/PCV/closed crankcase and EPA compliance we get all these wonderful things. Makes you wonder if the changes would have come without the need to comply with EPA.


So all you with the LB7, don't close off that little crankcase breather hose or you could be off to the races if a fuel line or injector starts leaking.


Would be interesting if DmaxAllitech thinks this is possible or even true.


"Fire in the Hole"





Edited by: Chevysrus
 

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Interesting point!
 

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Hmm, sounds concievable. I dont know how many fumes you would get with the diesel in the crankcase, and oil is not likely to burn as freely as diesel. I suppose its possible but dunno if that was the primary intent on the design.. It sure makes sense though. I heard of a powerstroke at the ford garage down the road that ran away. they did an oil change, but didnt drain it first, filled it up and away she went, was running away. smoked the whole building out and there was no way to shut it down, pulled batteries, pcm etc and it wouldnt slow down, I hear it ran for a good 20 minutes at some gawdawfull speed and then just locked up, they refilled with fresh oil and its been fine everysince.


I cant wait till these new engines come out, this coming as I am in the process of a 6 hour return volume test
 

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I wonder if the old design masked any of the injector noise and if the LLY will be louder?
 

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Professor said:
I wonder if the old design masked any of the injector noise and if the LLY will be louder?
I don't think much noise if any eminates from the injectors themselves. Could be true with non HPCR systems as they feed fuel in pulses all the way back to the pump (not all).

The Dmax system has much less "shock" in the injection event.
 

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How do you know if your truck has the new motor in it. I just got mine and it was not suppose to be on the floor till Jan 2... Was an order for someone that backed out.. Thanks
 

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GMC2500HD, quickest way is to pop the hood and look at a valve cover. If your injection lines connect to a nut in the center of the valve cover, you have an LB7. If your injectors and fuel lines are below the valve covers down closer to the exhaust manifold, you have an LLY. Anyone want to bet that it's NOT an LB7?
 

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i bet it is an LB7:) things are running Very very slow, and maybe have shiped out less than 200 engines, and that was yesterday, so i dont think he would have one yet
 

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Well it appears as if I just have the LB7 motor...






Ok so now I have a truck that no one will want in the future cause there will be a new more powerful motor out there...
 

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GMC2500HD said:
Well it appears as if I just have the LB7 motor...






Ok so now I have a truck that no one will want in the future cause there will be a new more powerful motor out there...
GMC2500HD: That will always be the case. There is always something bigger and better just around the corner. Just drive and enjoy what you have. If the LLY has any "new design" problems, you'll be glad you have the LB7.
 

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Be happy with no EGR to deal with... EGR has been a nightmare in some diesels but I'm shure the engineer's down at the Isuzu plant have done everything to aviod it. I would still be glad that none of the smoke that I'm putting out the exhaust pipe is not going back into my intake
. Looks like Cummins was the only one of the big 3 to pass emmisions without haveing to resort to EGR. New Cummins puts out pretty respectable numbers also.
 

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dmax, what do you mean that the vin code is 1 or 2?


I checked the specs on mine which is an 04 and the sticker says:


Heavy duty power package incls: 6,605.00, which is the same thing that they show on the website for the lly motor.


Thanks, just curious
 

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The runaway is possible if not probable IMHO. Ask a fireman why they won't park the fire truck near a suspected natural gas leak
 

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a64pilot said:
The runaway is possible if not probable IMHO. Ask a fireman why they won't park the fire truck near a suspected natural gas leak
That's the problem with "no spark" ignition.

Another thing to watch for is cleaning your foam type air cleaners. The instructions call for you to use soap and water. Some people use diesel fuel or kero. Anything flammable could cause the engine to run uncontrolled if it's left wet and exposed to the intake airstream.
 

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If You can't stop the fuel, You have to remove the air. I rememeber in diesel shop in high school haveng a big truck runaway. They shoved a bunch of rags in the air intake and it sucked them right up and blew them out the stacks.

John
 

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Yeah EGR can be a pain. I remember the inside of my 6.2L diesels intake manifold, when I had it off to service the injector pump.


I hear the Volkswagon TDI folks have to have their intakes off and cleaned at around 65K, because of all the soot buildup. My understanding is the TDI was designed for the cleaner, higher quality European fuel.
 

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As for the VW TDI - you are right - they tend to soot up with the combo of EGR and The CCV (oil) ... It's a big problem and many TDI owners tend to either vent the CCV out of the intake or do modifications to the EGR... and/or both.


I think a simple block off plate is the ticket.


Some of the TDI owners have put in Racor filter things to "clean" the CCV going into the intake so there won't be the oil vapors.
 

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Ranaways are easy to stop, just put your hand, a book, a rag or something over the intake on the air cleaner. no air no bang.
 

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I aint sticking my hand in front of a turbo inlet spinning at 60,000+rpm! You wouldnt feel it for days! it would take a metal plate for me to get close...
 
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