LLY: duramax knocking..
- Thread starter kman2468
- Start date
Any particular reason why? I che'ked my 03 that way and all the cylinders were within 10% of each other.....which isnt to say that all 8 were bent but....
Why would doing it one at a time not be accurate? Is it easier to turn over with all 8 plugs out and only one cylinder making pressure?
Use efi live an turn Injectors off one by one an see if it helps or makes the noise worse an I can't hear the noise but maybe stuck valve
I'm not exactly sure, but I think it has to do with eliminating as many variables as possible, such as if you have a bent rod or two, fried rings.... Anything that will affect the compression of a cylinder, when the affected cylinder(s) come up on the compression stroke, they'll have less resistance at the top of the stroke than the other cylinders, so there will be variations in the crack speed that could throw off readings for other cylinders. When you only have the one with the gauge "plugged", the other 7 cylinders will have no impact on reading the current cylinder regardless of their condition.
It could also have to do with the fact that no plugs in the motor will result in far less effort to turn it over, thus reducing battery drain.
The GM "How To" specifically states to remove all glow plugs, as does pretty much everything you can find on the 'net through a Google search....
Now, will it be "close enough" to give you an idea if you rmeove one at a time? Possibly.
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Ah. Ok. That makes sense. Never thought about anything else affecting cyl pressure when i did mine. Thanks, have to remember that.
Here is something Pat wrote
http://www.duramaxdiesels.com/forum/showthread.php?t=2091&highlight=compression+test
http://www.duramaxdiesels.com/forum/showthread.php?t=2091&highlight=compression+test
Very minor ....maybe. When a rod bends, your compressions ratio drops, and depending on how much bend it has is what varies the amount of CR drop. The lower you drop it, the less the fuel will burn completely, thus the white smoke.
Do a compression test, that will tell you a lot right there.
Do a compression test, that will tell you a lot right there.
got another vid...crappy sound again let me know if you can hear anything i cant
http://www.youtube.com/watch?v=CEZJdj1eu0M
http://www.youtube.com/watch?v=CEZJdj1eu0M
I highly highly highly doubt you have a bent rod. If you did you would see balance rates out way more than that. Still try to do a compression test though.
Do you have a lift pump? if so turn it off at idle and see if it go,s away. log your rail at idle if you get a chance