knocking when truck starts and at certian rpm

Every time that I start my truck and it hasn't been running for a while it eill knock when I start it. within about a min. or so it will fade away.But then it will also nock at about 1500 rpms. What the heck is
wrong woth my truck? Wil I be ablr to fix it?
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What heck is the truck, we are suppossed to guess that too?

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weltz wrote:

You may be dealing with tow different kncoks. One sounds like piston slap/knock when engine is cold and the other sounds like rod knock when engine is warmed up. It could be a very loose piston the knocks all the time too. A rod knock and startup would not fade away after a minute or so but piston slap can as it swells from heat.
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Thanks for the help snowman!
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I got an idea go to tools, options, click on the tab (spelling), check the box that says always check spelling before sending!!
Now to answer your question, if it is a 5.7 or 6.0 V-8, or 4.3 V-6, and it was build on or after 1994 you probably just have piston slap. This gets noisier at about 1500 rpm, but it usually goes away when the engine is warmed up. If yours doesn't go away, or gets louder it is probably a rod bearing.

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