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05-11-2018, 10:59 PM | #1 |
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Join Date: Nov 2017
Location: Aledo, TX
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Tapping from engine when going from no throttle to throttle
When my engine is “coasting”, in gear or not, and I add throttle I get two or three sharp “clacks” from somewhere in the engine. I’m guessing slack in the valvetrain is causing the noise as the components go from dragging to being pushed? Any suggestions on where to start troubleshooting? The noise only exists in this transition period from closed throttle to open throttle.
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05-11-2018, 11:19 PM | #2 |
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Join Date: May 2010
Location: now Kuna, Idaho
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Re: Tapping from engine when going from no throttle to throttle
Since the valves are pushed open by the cam lobes and closed by the springs, they don't know if they are "dragging or being pushed". On the other hand, the pistons, wrist pins, rods and mains are all affected by changes in combustion pressure caused by going from closed to open throttle. If you can duplicate the noise by opening the hood and moving the throttle by hand, try grounding out each spark plug one at a time and see if the noise lessens or goes away.
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05-12-2018, 10:02 AM | #3 |
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Location: So Minn
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Re: Tapping from engine when going from no throttle to throttle
If you open the throttle a little then let off and repeat that several times and you hear the clacks rattle between on and off it is a pretty good sign of a bad rod bearing.
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05-12-2018, 10:18 AM | #4 |
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Location: Lynden, WA
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Re: Tapping from engine when going from no throttle to throttle
Aluminum timing gears can make some interesting noises.
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05-12-2018, 05:45 PM | #5 |
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Re: Tapping from engine when going from no throttle to throttle
With the hood open, work the throttle by hand and isolate the noise. We need to know where the noise seems to be coming from. Grounding/shorting each cylinder as 40 mentioned will help if the noise is from a certain cylinder.
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05-12-2018, 06:43 PM | #6 |
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Re: Tapping from engine when going from no throttle to throttle
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05-13-2018, 06:07 AM | #7 |
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Join Date: May 2010
Location: Largo Florida
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Re: Tapping from engine when going from no throttle to throttle
LOL. Its funny how those pesky little horn bolts can cause the timing gears to rattle around.
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