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horrible engine knock. what is it

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Old Jul 5, 2011 | 10:02 AM
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From: madison tn
Default horrible engine knock. what is it

about a year ago i had a wastegate malfunction and spiked the boost gauge. of course it blew both head gaskets. after putting the heads back on it had a horrible knock while its cold. so i figured i would drive it until it popped. that was over a year ago and still the same noise. really loud at idle then dulls down to almost nothing when its hot. still has compression and oil pressure. any ideas what is going on?
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Old Jul 5, 2011 | 10:06 AM
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It is piston slap! Mine does the same exact thing and it is loud and annoying but once it warms up it doesnt do it. Trust me I know your pain...mine just started it recently and I asked everyone on here and at Texas speed and they all told me the same thing. It will be fine but I cant really take it, I will be having mine looked at soon. Everyone told me not to worry so I took it to heart it has been running fine. Good luck.
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Old Jul 5, 2011 | 10:28 AM
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i thought i had heard piston slap before, but this is crazy loud. mt neighbor from 2 houses down came over and asked me what it was when i started it
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Old Jul 6, 2011 | 12:36 AM
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Have you checked your valvetrain, pushrods, rockers etc? My money is on a lifter, same thing happened to my car, it had a horrible knock and once it warmed up for it got allot quieter. I know it wasn’t piston slap, it was way way to loud.
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Old Jul 6, 2011 | 08:46 AM
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so pull the covers and check for valve lift?
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Old Jul 6, 2011 | 01:22 PM
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I would check the rockers for excessive movement; there is a bulletin on the stock rockers having problems with their bearings and coming apart in the engine. I would also pull the pushrods and check to see if they are all straight. Just roll them around on a perfectly flat surface. Then if all of that looks fine, the next thing I would check is the lifters. Sadly the only way to check them is to pull the heads. But if one of the lifters is bad, I would replace all of them with aftermarket ones. Its worth the time and money if you ever plan on running a cam and heads etc. I picked up my set of Comp lifters for around $200 from Texas Speed. But before you pull the heads I would check every other place your noise could be coming from. One thing you could do is pull off the belt and start the engine, for a very short time, no more than 30 seconds. This would remove all the possible things making noise on the belt system.

Bulletin Number for the rockers: 02-06-01-029

Hope this helped and good luck.
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Old Jul 6, 2011 | 03:08 PM
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i checked the rockers and the pushrods they are good. i guess the next step is pull the heads again...
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Old Jul 6, 2011 | 09:40 PM
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Where is the noise coming from? Once you have heard rod knock you will never forget it... Different frequency and rate of sound....You will know.... Compression check or even better leak down will tell you where the problem is...
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Old Jul 7, 2011 | 09:22 AM
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Most likely a piston contacting a head when its cold. As the engine warms up the block expands away from the piston height.
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