Chevy/GMC Duramax 01-04 LB7 Discussion of Chevy and GMC Trucks with LB7 Duramax Turbo Diesel Engines

LB7 tear down

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Old Nov 23, 2013 | 03:12 PM
  #71  
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i changed to fuel lines to clear ones wrapped the stock bleeder screw with thread tape i primed the filter till it was nothing but fuel then bled the pressure thing by the altonator for about 2 hours lost about a gallon and a half of fuel but never could get this air out im thinking the filter housing maybe cracked somewhere im not sure where to go next.
 
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Old Nov 23, 2013 | 04:51 PM
  #72  
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Originally Posted by Walker.B
then bled the pressure thing by the altonator
try doing it again with out bleeding the pressure/air form this fuel test port. every time you open it it has the chance to introduce air as this line is normally under a vacuum.
 
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Old Nov 23, 2013 | 05:15 PM
  #73  
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at first i did i just used the bleeder screw but after an hour and a half and nothing but fuel coming out i started using the other thing and the bubble got to smaller the size it is now and no matter how much i bleed/prim at ether point it will not go away at all and no air comes out at ether point now i just came in ive been out there trying to clear it for 4 hours. as for it being under a vacuum every time i pressed it after priming till rock hard it shot out one time it shot out about a foot in front of my truck is it bad it dont seem to be under vacuum?..........im at such a loss i dont understand how im getting nothing but fuel yet i see this huge bubble that never moves
 
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Old Nov 25, 2013 | 10:59 AM
  #74  
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i changed to hose dad put on with one longer so all of the clamp clamped it i was able to get the bubble about half the size it was but i cant get it gone. how do i check the filter housing to see if its cracked? i was thinking on the out side put a mec pressure gauge and on the in side a valve and use the air compressor to build 5-7 PIS the close the valve and see if it leaks down would this work since its air not fuel?
 
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Old Nov 25, 2013 | 02:39 PM
  #75  
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i would test it with a vacuum if you can. trying to push diesel though a hairline crack will make for a very slow leak that will be hard to find. with a vacuum air will get through the cracks faster.
 
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Old Nov 25, 2013 | 03:28 PM
  #76  
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ok i think i have an 110V vacuum pump in the shop that pulls like 15 PSI is that to much?
 
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Old Nov 25, 2013 | 11:46 PM
  #77  
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should be perfect.
 
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Old Nov 26, 2013 | 09:49 PM
  #78  
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well my housing is ok I had the lines going in and out of the housing reversed I changed and it's almost cranking it will spin about 15 sec start spinning faster and feeling like is trying to hit. I'm calling it a night I'll try again tomorrow
 
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Old Nov 27, 2013 | 12:59 AM
  #79  
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that will do it. there is a check valve in the filter housing that will make it difficult to pull fuel backwards through it.
 
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Old Nov 27, 2013 | 04:03 PM
  #80  
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yeah me and my dad put the hoses the way they look liked they went after watching the fuel move backwards we decided to look at a buddy's fed emissions lb7 look at etch other and said well there's your problem so it tried to fire like spinning faster but it was late so I'll go back out In a few and try it again maybe she'll fire

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i just came inside i couldnt get it to prime up at all. then my dad told me he took off the return line lose on the drivers side put a pump on it then took the lines lose off the filter housing and drained the lines empty so now i have to prime all of it how do i do that? i was thinking about just ordering an air dog and be done with this nightmare....

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i got it primed up again rock hard no air and still no start so i took the returnline lose put a hose on it to a can outside of the truck and when its spinning over i get a very slow trickle out of it
 

Last edited by Walker.B; Nov 27, 2013 at 04:03 PM. Reason: Automerged Doublepost
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