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

2003 lb7 shut off at drive thru

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Old May 3, 2015 | 12:51 PM
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From: Fyffe, Al
Default 2003 lb7 shut off at drive thru

Was going to work the other day and my truck idled up mildly then shut off in a drive thru. It wouldn't start back soj I had it towed in. When it got to my house fuel was pouring out the transmission bell housing. After about a gallon off fuel it quit. Still want start and not leaking now. Giving code that low pressure in fuel rail. Loosened #2 injector line and not much fuel coming out of it. Pump, pressure relay, any ideas? Will start with either and run just will not start on its on.
 
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Old May 10, 2015 | 02:18 PM
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Fuel leaking from the bell housing sounds like a leak in the valley of the engine. It will spill out the back of the engine dripping down the bell housing. I would inspect all of the fuel lines for cracks and other problems.
 
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Old Jun 16, 2015 | 10:24 AM
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Heres what I got as of now. I'm getting fuel in the oil. I removed the valve cover and replaced the injector high pressure lines and started it up but no leaks. Put it back together and let it run for 30 min and drove up the road about a mile and back no fuel in oil. Got in it and went to my sisters about 3 miles away. when I left her house oil pressure started dropping, got home and fuel in oil. Remove valve cover again, replaced high pressure injector lines, unplugged pressure control relay on pump to max out pressure. Started truck up and no leaks. Drove out my driveway and back and still no leaks. Twice I have put it back together with no leaks and get 4 miles and it starts dumping fuel in the oil. Where could it be coming from that it only does it after going 4 or 5 miles? Need help bad! Injectors aren't very old. lines look good.
 
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Old Jun 16, 2015 | 12:34 PM
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Started back up and #2 injector return rail bolt spit fuel and air just for a second. luckily I was looking right at it. pulled it off and the washer had broke off the back half when installing. decided to pull the injector back out while I was that far and the big oring that seals off in the cup was cut all to pieces(haven't figured out how) so replaced it. Put the injector back in and started reinstalling the return fuel line and the bolt that goes in the head broke. got to looking at it and it looked like it had a factory defect was deformed and looked like a factory crack had been in it.
 
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Old Jun 17, 2015 | 11:15 AM
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yep, many have leaked at the return line crush washers. the older injectors would crack and leak into the oil but that was fixed awhile back using a different alloy in the injector body.

the crush washers are supposed to be one time use and if you take it off it will need new ones or risk more leaks. the O-rings should be lubricated so they don't bind going in. had mine out a couple of times and never had them leak or have O-Ring issues.

on the hold down bolts, some have suggested replacing those too as it seems they stretch and start loosing their clamping force. i reused all of mine but i can see replacing them after a few re-torques. never heard of one braking though. like you said, may have been factory defect.

once you work with crush washers enough you will start to get the feel for how much torque they need to seal. just like the feel for when a bolt is about to break, crush washers have a unique feel for when they start to deform and seal up. i dont use a torque wrench on any of my crush washers and dont have any problem with leaks. when i first did my injectors i used a torque wrench and it worked but felt like it was just shy of properly crushing the washer so i gave it a little more. maybe give yours an 8th to a 1/4 more turn. that's what mine seem to take
 

Last edited by 2004LB7; Jun 17, 2015 at 11:17 AM.
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