rattle at higher RPMs

[MrLaramie]

Was towing the boat the other day and noticed that when my RPMs are over 2500 there's a weird and constant rattling sound coming from somewhere on the passenger side. It happens when i'm not towing too, but I'm rarely punching it to get the RPMs up high.

the rattle sounds kind of like a rattle in a small spraypaint can.

any ideas on what this could be?

it's friggin annoying.

 

[StoneDude76]

Look at your exhaust. It runs down the passenger side. My 09 would rattle and it drove me nuts. I finally got under the truck with a rubber mallet and banged around. Here it was the clamp right after the y pipe that was loose.

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[Rampant]

What octane gas are you using? You could be getting some detonation if you're using too low octane, especially when under load.

 

[MrLaramie]

Look at your exhaust. It runs down the passenger side. My 09 would rattle and it drove me nuts. I finally got under the truck with a rubber mallet and banged around. Here it was the clamp right after the y pipe that was loose.

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it doesn’t sound like a part is loose. it’s more like something in the motor. the rattle seems to vary with the rpm speed.


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[MrLaramie]

What octane gas are you using? You could be getting some detonation if you're using too low octane, especially when under load.

i’m running 87 octane. never thought about how putting it under load could be impacted.

the plugs haven’t been changed in 60k miles. which could maybe have an impact?


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[Rampant]

Both could absolutely be factors. I don't think they had the 100k plugs yet in '09, did they? Either way, try some higher octane gas and see how it reacts. You probably won't be able to tell any difference if you're not towing or hauling.

 

[MrLaramie]

Both could absolutely be factors. I don't think they had the 100k plugs yet in '09, did they? Either way, try some higher octane gas and see how it reacts. You probably won't be able to tell any difference if you're not towing or hauling.

hmm. yea i guess the next time i drag the boat i’ll run 89 and see what happens. thx for mentioning this.

the 09’s mention swapping plugs every 30k miles, which to me, sounds insane. but this is a “new to me” truck. so i dunno


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[huntergreen]

Sounds to me like you need a plug change and to use a better gas.

 

[Rampant]

Sounds to me like you need a plug change and to use a better gas.

Legit advice.

 

[MrLaramie]

Sounds to me like you need a plug change and to use a better gas.

by better i’m assuming you mean higher octane. I only buy gas from super high volume stations, under the assumption that they’ve got “better gas” bc it’s been sitting in their tanks for shorter periods of time.


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[huntergreen]

Actually, I meant a top tier gas.

 

[Rado]

Also check the heat shield on the Converter ! They rattle at certain RPM'S when the welds break, Worth a shot Please post what you find

 

[MrLaramie]

For anyone curious... I solved the issue.

Swapped the plugs and cleaned the fuel system and the last few times i've towed the boat, no more knocking sound. So I'm thinking it was the ignition issues from plugs that were 110k miles old.

Also I never changed gas from the 87 octane I was running. Wasn't sure how to buy better quality gas than what I was getting... taste it? Chase it like a shot of tequila?

As long as the 87 still runs and no knocking, i'll keep doing that.

thx everyone for helping me chase down the issue.

 

[chrism1367]

Try moving to 89 octane, may help also

 

[Ramnewbie]

Also check the heat shield on the Converter ! They rattle at certain RPM'S when the welds break, Worth a shot Please post what you find

I had a car one time that got a piece of gravel in the heat shield, drove me nuts trying to find the rattle. Of course once I found it there was no way to get it out, I don't know how in the hell it got on there. It finally rattled long enough that it must have wore itself down and fell out.

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[Rampant]

For anyone curious... I solved the issue.

Wasn't sure how to buy better quality gas than what I was getting... taste it? Chase it like a shot of tequila?

As long as the 87 still runs and no knocking, i'll keep doing that.

thx everyone for helping me chase down the issue.

This is how to find better quality gas.

 

[chrisbh17]

Just an FYI - check to see how much ethanol is in whatever gas you end up with (unless you are blessed enough to have easily available ethanol-free)

I had been using Costco for my Hemi..."top tier", cheap, etc. Then I looked at the sticker on the pump saying its 15% ethanol. For shiggles, I changed to Mobil which only had 10% ethanol.

Now Ive "gained" about 1.5 mpg. Of course, the 15% ethanol stuff was cheaper, but since Costco only has 87 or 93, I put in 93.....Costco's 93 is only 3 cents cheaper than Mobils 89. So my gain in MPG more than offset the "extra" expense of 3 cents per gallon.

 

[MrLaramie]

This is how to find better quality gas.

So if i understand their site correctly... If a brand is listed (mobil / chevron / costco etc), then all of their pumps and octanes should also have the Top Tier logo, and i'm good to go?


Cant say i've ever noticed the TopTier logo, but i've definitely bought gas as those stations before.

 

[MrLaramie]

Just an FYI - check to see how much ethanol is in whatever gas you end up with (unless you are blessed enough to have easily available ethanol-free)

I had been using Costco for my Hemi..."top tier", cheap, etc. Then I looked at the sticker on the pump saying its 15% ethanol. For shiggles, I changed to Mobil which only had 10% ethanol.

Now Ive "gained" about 1.5 mpg. Of course, the 15% ethanol stuff was cheaper, but since Costco only has 87 or 93, I put in 93.....Costco's 93 is only 3 cents cheaper than Mobils 89. So my gain in MPG more than offset the "extra" expense of 3 cents per gallon.

All of the pumps I tend to hit say "up to 10% ethanol", can't say I've ever noticed a higher % than that.

Is continuously switching between Ethanol mix and Ethanol free an issue? I know with my outboard 2-stroke on the boat that it can really jack with how the motor runs, so I stick to what has worked so far.

 

[Rampant]

So if i understand their site correctly... If a brand is listed (mobil / chevron / costco etc), then all of their pumps and octanes should also have the Top Tier logo, and i'm good to go?


Cant say i've ever noticed the TopTier logo, but i've definitely bought gas as those stations before.

Nah, I don't remember seeing the symbol on any pumps. Most say their highest octane contains the most detergency. Who knows how much of that is true vs snake oil? I run 89 so I think maybe I at least get some of the "good stuff." Plus my truck calls for it.

I always thought any ethanol was bad. I found that to be false. In modern vehicles, anyhow. In VA, I could get ethanol-free easily, so I tried it. 89 octane. From the same station, same octane, two consecutive tanks of each. I actually got slightly worse mpg, hand calculated while using ethanol-free.

I definitely use ethanol-free in any small engine and carbureted vehicles. Newer vehicles' fuel systems are either coated with an anti-corrosion compound or are made of a non-metalic material, so they don't usually have ethanol-related issues.

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