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I need input. I just finished a head gasket replacement on my 94 K2500 Sub. What a job!!!
Primed fuel system and started engine. Life is good at this point. Then, I noticed a sharp rap in the engine that seemed to go from the turbo side to the drivers side of the engine. I shut down looked the thing over from top to bottom. Nothing seemed out of sorts, so I started the engine again and increased speed a bit. When I brought the engine back to idle the noise was not as loud. Any ideas? I don't want to make a minor problem a major thing. Thanks
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i don't know what it is but mine did that both times i've done the heads and then went away. i attributed it to a cold dry start both times the vehicle has been down for a few days to a week with no oil circulation. its best to unplug the fuel sol. on the pump and crank it a bit(10 sec.a few times) to push oil through all the dry passages b4 starting eng. plus when you first crank it up your injectors will blow air out of them b4 it will even start. some people even leave the fuel feed to the injectors a little loose so that they can bleed the air out then tighten them down after a short start.
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One or more of the lifters could have drained down as well. It happened to me on a gasser motor. Don't know if it's that much similar, but once the motor ran for 10 minutes or so, the lifter refilled and the noise went away.
Scared the biheevejeebees out of me, too. Remind me to tell you that story.
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Thanks for your input. When I first noticed the sound, I was sick. I have now driven my Sub twice on short trips 2-3 miles. I have the following symptoms:
No "rap" at start-up
"Rap" appears as engine idles down
"Rap" dissapears as engine speed increases (or is overcome by the fan sound)
I have also notice that engine runs slightly warmer than before. Is this due to air in the cooling system before not allowing accurate reading? All help/suggestions welcom.
