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Ask Gm Tech (Cam) Your Own Question
Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 year experience.
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Gmc 2500 Series: 06 lly combustion noise heavy black smoke

Customer Question

06 lly combustion noise heavy black smoke 250 psi all 8cyls
Submitted: 1 year ago.
Category: GMC
Expert:  Gm Tech (Cam) replied 1 year ago.
Hi there, I am Cam. That is far too low of compression. Minimum for this engine is 300 psi. Can you tell me what was happening prior to this issue? Is the truck chipped?
Customer: replied 1 year ago.
yes i no compress to low should be min 300 but all8 cyl the same did have program at one time customer had it removed prob 150 km ago customer was backing truck up in driveway just started to knock puff heavy black truck sat for feww months until it casme to me money reasons
Expert:  Gm Tech (Cam) replied 1 year ago.
How many KMS on the engine? Any idea what level the chip was set at?
Expert:  Gm Tech (Cam) replied 1 year ago.
Do they have the blocker plates in the EGR or whats happening with the EGR?
Customer: replied 1 year ago.
300km on truck no plates egr never been touched
Expert:  Gm Tech (Cam) replied 1 year ago.
Do you have the means to disable injectors one at a time and see if any make a difference in the way it runs that is not comparable to the other ones?
Customer: replied 1 year ago.
yes can use scanner have not tried that yet will try tomorow compression is what gets me all 8 and gauge good
Expert:  Gm Tech (Cam) replied 1 year ago.
It may have hit overspeed and slightly bent some the valves. I have seen that before.
Expert:  Gm Tech (Cam) replied 1 year ago.
It may have hit overspeed and slightly bent some the valves. I have seen that before.
Expert:  Gm Tech (Cam) replied 1 year ago.
It may have hit overspeed and slightly bent some the valves. I have seen that before.
Customer: replied 1 year ago.
heavy black and knock is over fueling only misfired on 4 and 6 both those injectors have been replaced and compress same as all others
Expert:  Gm Tech (Cam) replied 1 year ago.
Lets see what the balance test does then tomorrow.
Customer: replied 1 year ago.
k thanx have to put all glow plugs back in and back truck outside 6pm here now il respnode when no whats up tomor
Expert:  Gm Tech (Cam) replied 1 year ago.
Sounds good.
Customer: replied 1 year ago.
how are ya today did balance test #8 when disabled ride of knock i guess that injector no good still no understanding this compression being 250 on all 8 just checked another 6.6 to confirm my gauge 385psi on it so gauge good
Expert:  Gm Tech (Cam) replied 1 year ago.
IT may be that the engine is just worn out. Lets change that injector and see what happens.
Customer: replied 1 year ago.
sounds good thanx
Expert:  Gm Tech (Cam) replied 1 year ago.
OK.
Expert:  Gm Tech (Cam) replied 1 year ago.
Please reply back if you need additional help or information regarding this issue. If there is nothing more I can get for you today, then please rate me 5 starts/faces if my answer was helpful. You can reopen/reply to this thread directly to me at any time by replying to it and I will respond as soon as I am able. Please keep in mind that as experts on this site, we are only compensated for our time spent helping customers rating 3-5 stars/faces. Be sure to bookmark this page as a favorite (CTRL D on PC and CMD D on Mac) to reply with results or ask more if you need. Thanks again for using Just Answer. Cam.