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Engine knock on start up?


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I have a 90 Lumina with the 3.1. When the engine is cold and you start it up it has some what of a knock/tick, but once the engine warms up it goes away :think:.

 

Are the 3.1's known for this?

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These engines are famous for piston slap, it only occurs when cold and as you've noted it disappears once the engine has warmed up. If you're worried about this *knock* pick up a stethoscope and use it to find the location of the knock when it's occurring.

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These engines are famous for piston slap, it only occurs when cold and as you've noted it disappears once the engine has warmed up.

It would be more accurate to say that it's WORSE when cold, if the pistons/cylinders are bad enough they will still knock when fully warmed-up.

 

My 3.4 USED to only knock when cold. Now, the knock is quieter, but still there when at normal operating temp--and has been for tens of thousands of miles, and many years.

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I read this on another forum and the person said: I dumped a bottle of motor honey or Rislone in after an oil change, this noise problem went away shortly after. Change the oil, don't use the additive and the noise came back in a couple days. It took about 3-4 oil changes using motor honey/Rislone before the noise was eliminated.

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