After replacing the injectors on 04 GMC Sierra Duramax it starts up and runs. Sounds off but runs. After 5-10 seconds it starts smoking from under/behind the alternator. With it running I can't see the smoke because of the fan but after shut down it smokes pretty good from somewhere. I can't tell because of hoses and wires if it is coming from the valve cover. Since the timing sounds off I would think it is from inside but I'm not sure how smoke would get out of the valve cover so fast. Any advise?

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Looks like I did something wrong. I'm burning coolant. Not sure exactly how yet but looks like the valve covers are coming back off. I'm guessing one of the seals or injector caps (boots or sleeve whatever they are called) is letting coolant into the oil. Wonder if I'm getting oil into my coolant? This could be fun.