Engine making a knocking type noise [Archive] - GrandAmGT.com Forum


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05-24-2009, 07:00 PM
Upon start up cold engine it would make a knocking type noise sounds like its coming from the top on the engine. and after it warms up it seems to go away but every once and awhile you can hear it when its hot. Im believing that is a lifter or rocker noise but just wanna see what everyone thinks. its a 3400 V6

05-24-2009, 07:03 PM
usually these 3400s got piston slap...some got it bad some dont...the lifters are noisy too...if the sound goes away as it warms up or comes and goes i wouldnt think theres anything to worry about as far as the motor crappin out

05-24-2009, 08:45 PM
happens to A LOT of later model GM motors. not exactly sure why. Its nothing to worry about. If the motor has a ton of miles on it, might not hurt to pull the covers and check the rockers. make sure they are still torqued down. But thats faaaar from necessary. Just an extra piece of mind.

05-25-2009, 12:34 AM
Mine has had it for 16k and has not gotten worse. I have the same thing... It's most likely a ticking lifter. Don't worry about it. Only worry about it if it does not go away when warmed up. You will hear it slightly when warm... but if the noise remains the same from cold to warm, then I would start worrying. Otherwise it's all good.