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

Help with blow by issue, injector issue

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Old 04-14-2013, 11:10 PM
Rods Dirtymaxlb7's Avatar
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Default Help with blow by issue, injector issue

Hey pros I just changed all the injectors in my lb7 and now there is excessive smoke coming out of the blow by valve and if I open the oil filler cap it comes out like a chimney. I checked the oil and it doesn't look contaminated with fuel. I changed all the gaskets on the return lines and the new ones on the injectors, new rubber gasket on lower valve cover. When I got everything back together I started it up and it idled perfect and purred like a dream. So then I took it on a test drive and done great until it pulled the small hill right by my house, It all of a suddenly died but started back up right after and I made it home, Now it has a kinda rough idle and smoking like crazy out of the blow by. The radiator hose isn't hard or anything either and coolant isn't bubbly. Any help will be greatly appreciated. Oh and I didn't replace the injector cups none were damaged while getting out the injectors.
 
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Old 04-15-2013, 08:36 AM
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does the oil smell like diesel? is it over full? Is the engine making any odd sounds?
 
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Old 04-15-2013, 10:18 AM
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No it isn't over full and doesn't smell like diesel it did however make a ticking noise from driver side.
 
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Old 04-15-2013, 10:33 AM
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ok, it sounds like either the injector hold down bolt might not be tight or has backed off and caused the injector oring to blow. If you can get hold of a scan tool you can narrow it down to the problem cylinder before you go back into the engine.
 
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Old 04-15-2013, 10:53 AM
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On a tight budget which scan tool do you recommend?
 
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Old 04-15-2013, 11:18 AM
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I would try and borrow or take truck to a garage. You only need it for a minute to check bal. rates and see which cylinder is out of spec.
 
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Old 04-16-2013, 07:45 PM
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I found the poblem 2 injector hold down brackets backed off and was spraying fuel inside valve covers.
 
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Old 04-17-2013, 08:41 AM
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good deal. Ive seen them blow out so bad they break the fuel return rail and really cause a mess. Have you checked to see if the copper washer and oring are destroyed?
 
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Old 04-17-2013, 10:14 AM
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Orings were destroyed and the copper washers were ok. I dont see how they backed off. I put locktite on them this ho around.
 
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