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Offline oldtexan

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5500 - 6000 RPM Rattling BB's
« on: July 19, 2019, 06:24:07 PM »
I've read several posts about vibration around 5500 RPM.  I experience  that, but my question has to do with a noise that occurs starting at about 5500 RPM and smoothing out and disappearing around 6000 RPM - it sounds like there's several BB's bouncing around in my valve train.  I think this is normal behavior of the engine, so the noise does not worry me - but I'd like to know exactly what causes it.

Anybody know?  Or have theories?

Offline motorboy

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #1 on: July 20, 2019, 04:24:45 AM »
My 2014 did the same thing-my 2019 does not-also it's just as hot where you are as where I am try mid grade gas it helped with the running of both
« Last Edit: July 20, 2019, 04:27:32 AM by motorboy »
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Offline oldtexan

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #2 on: July 20, 2019, 12:26:30 PM »
motorboy, so you think the noise is an engine knock caused by low octane fuel?

Offline Mence

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #3 on: July 20, 2019, 02:08:53 PM »
What mileage?

Vibes are standard, rattle isn't, shims need redoing?
« Last Edit: July 20, 2019, 02:10:00 PM by Mence »

Offline motorboy

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #4 on: July 20, 2019, 02:24:13 PM »
*Originally Posted by oldtexan [+]
motorboy, so you think the noise is an engine knock caused by low octane fuel?
Can't say for sure but with our heat it's very possible worth a try and it did help both--like you I wondered why only at that RPM what's going on inside the engine only thing I could think of that maybe at that RPM the timing goes full advance --high heat +load=ping
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Offline oldtexan

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #5 on: July 20, 2019, 03:39:22 PM »
motorboy, the noise does sound a bit like the "pinging" that I've heard from car engines, which I believe can be caused by low octane fuel, messed up timing, and overheating.

Today I did an experiment.  I was traveling at 50 something on a rural road and shifted into a gear that allowed me to be at something over 6000 RPM.  I activated the engine cut off switch, left the clutch out, and of course slowed down.  When I got to just below 6000 RPM, the same noise occurred and then disappeared as I slowed to below about 5500 RPM.  Since this was presumably with the ignition off, it seems like this eliminates any ignition contribution to the noise.  But, I plan to fill up the next time with the expensive stuff and see what happens.

I hear the noise best when my visor is slightly up, and when at speeds below 60 due to lower wind noise.
« Last Edit: July 20, 2019, 03:40:22 PM by oldtexan »

Offline oldtexan

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #6 on: July 20, 2019, 08:42:57 PM »
*Originally Posted by Mence [+]
What mileage?

Vibes are standard, rattle isn't, shims need redoing?

Mileage is 11,500 miles (18,500 kilometers). 

Offline oldtexan

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #7 on: July 21, 2019, 07:43:36 PM »
Here is an MP3 of the noise in question (by the way, maybe listen to it, but don't spend much time analyzing it until you read the next post).  You'll hear several RPM cycles, from about 5500 RPM to 6000 RPM and then down to less than 5500RPM, then repeat.





Offline oldtexan

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #8 on: July 21, 2019, 07:48:51 PM »
Well, I discovered the problem.  It's embarrassing to admit what it is, but since it's not the most embarrassing mistake I've ever made, I'll admit it.  And no, I won't reveal what the most embarrassing thing is.  Here's the culprit:



That's right, a cheap highway peg vibrating on the engine guard.  NOT BB's in the valve train.

Offline Mence

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Re: 5500 - 6000 RPM Rattling BB's
« Reply #9 on: July 21, 2019, 08:25:31 PM »
Good spot....and a whole lot cheaper than a possible engine rebuild!

 


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