Pulley? Violently Shaking? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

636 · 03-07-2013, 04:43 PM

I'll have a video up soon, but I was looking at my engine bay today with the car on, and the second pulley? (Not too sure what it is, I'm a noob at this stuff.) Around the belt was shaking side to side pretty violently it looked. Is this normal on these cars? Here's a picture of an engine bay I found online, I circled the problematic one.

The other two are working fine, but this one looks like it's shaking side to side very fast.

That appears to be the belt tensioner, is it supposed to vibrate a lot?

[ame="http://www.youtube.com/watch?v=ZJLgZkjbS8g"]FRS Belt Tensioner + Cricket Noise - YouTube[/ame]

Just searched and said it's normal? But, I'm still a little skeptical..any ideas? Just ran out and took a video after turning my car back on, wasn't really shaking at all. But I took a video anyway, and I believe the crickets started? I dunno, I think I'm being overly-cautious, but I can never be too sure with this car..

Chimpo · 03-07-2013, 04:51 PM

Is the car acting strange? Has something changed? Is there anything different now other than you noticed it? Without seeing a video, unless it's moving several inches each way I think you'll be okay.

xwd · 03-07-2013, 04:54 PM

That is normal although I agree a bit unnerving.

636 · 03-07-2013, 04:57 PM

Quote:

Originally Posted by Chimpo

Is the car acting strange? Has something changed? Is there anything different now other than you noticed it? Without seeing a video, unless it's moving several inches each way I think you'll be okay.

I'll try to take another video after I'm driving. It was shaking like a MOFO. But for some reason when I turned it back on, seemed to be fine.

whtchocla7e · 03-07-2013, 05:49 PM

Was it a cold start? Does it go away after engine is warmed up a bit?

JesseE · 03-07-2013, 05:51 PM

100% normal :-)

strat61caster · 03-07-2013, 06:20 PM

Some parts are meant to flex, it allows for the forces to be distributed in such a way that the parts don't fail because the stresses are below the threshold that will cause permanent damage. If it seems to be consistent with what other people are seeing then it was built that way on purpose and only time will tell if it's a flaw.

Draco-REX · 03-07-2013, 06:37 PM

Completely normal. That pulley is mounted to a spring-loaded belt tensioner that's designed to keep the overall tension of the belt at a set point. As the engine goes through its cycles, and the alternator adjusts for loads, and other things occur, loads on the belt can change so this pulley will bounce, even rapidly as you're seeing, to maintain the proper tension.

Automatic Belt Tensioners are used on MANY cars. It allows the engineers to design an accessory system that uses one LONG belt rather than multiple smaller ones. Otherwise you wouldn't be able to compensate for the changes in length and tension with such a long belt. It also reduces the time needed to change the belt since you can just swing the tensioner out of the way to remove the belt and put the new one on.

636 · 03-07-2013, 08:04 PM

Thanks guys.

whitefrs · 09-03-2013, 06:26 PM

im having the same issue. is this normal then?

RallySport Direct · 09-03-2013, 06:35 PM

Quote:

Originally Posted by whitefrs

im having the same issue. is this normal then?

Yep 100% normal, basically it is just soaking up the tension the engine, A/C, and Alternator create on the belt.

Thanks,
Rick

loogs · 10-03-2013, 02:09 PM

what do you guys think of mine? listen past the crickets, past the exhaust and past the pulley. theres a weird sound and its got me concerned. it only happens when i turn the AC on.

[ame="http://www.youtube.com/watch?v=WjZHWAkhkFI&feature=c4-overview&list=UUL4djS2xrkT2ist4nlAvRMg"]Fa20 AC on - YouTube[/ame]

Razz · 10-03-2013, 03:48 PM

^ I hear the whistle.

That needs to be lubed.

The other clunking sounds wrong.

Crickets are DI so that's okay.

The other sound is like an echo between two metal pieces.

However if it occurs when AC is turned on it is the compressor.
And that's pretty loud for a compressor.

King Tut · 10-03-2013, 04:14 PM

Normal.

03-07-2013, 05:49 PM	#5
whtchocla7e Senior Member Join Date: May 2012 Drives: 2013 FR-S Hot Lava Location: CT Posts: 424 Thanks: 30 Thanked 222 Times in 81 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Was it a cold start? Does it go away after engine is warmed up a bit? __________________ Live to drive another day

09-03-2013, 06:26 PM	#10
whitefrs Love Boost!!!!!!!! Join Date: Jun 2012 Drives: Whiteout Scion FR-S Location: Long Island NY Posts: 3,612 Thanks: 429 Thanked 902 Times in 606 Posts Mentioned: 87 Post(s) Tagged: 3 Thread(s)	im having the same issue. is this normal then? __________________ ༼ つ ◕_◕ ༽つ I LOVE BOOST ༼ つ ◕_◕ ༽つ

10-03-2013, 04:14 PM	#14
King Tut NASA SpecE30 Racer Join Date: May 2012 Drives: 2006 Honda S2000 Location: Gulf Breeze, FL Posts: 7,279 Thanks: 607 Thanked 5,759 Times in 3,055 Posts Mentioned: 274 Post(s) Tagged: 10 Thread(s)	Normal. __________________ - King Tut Street/Track Car: 2006 Honda S2000 TT3 \|\| Race Car: 1987 BMW 325is SpecE30 \|\| Tow Vehicle: 2014 RAM 1500 EcoDiesel Sold Cars: 2012 BMW M3 \|\| 2013 Subaru BRZ \|\| 2012 Porsche Cayman R \|\| 2009 Chevrolet Z06 \|\| 2009 BMW M3 \|\| 2004 BMW M3 \|\| 2004 Nissan 350Z

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03-07-2013, 04:51 PM	#2
Chimpo Senior Member Join Date: Sep 2012 Drives: '15 STi Ltd Location: Probably a location near you! Posts: 297 Thanks: 37 Thanked 149 Times in 61 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Is the car acting strange? Has something changed? Is there anything different now other than you noticed it? Without seeing a video, unless it's moving several inches each way I think you'll be okay.

03-07-2013, 04:54 PM	#3
xwd Senior Member Join Date: Feb 2012 Drives: 2013 DGM Subaru BRZ (Subie #9) Location: ATL, US Posts: 2,667 Thanks: 123 Thanked 861 Times in 552 Posts Mentioned: 32 Post(s) Tagged: 0 Thread(s)	That is normal although I agree a bit unnerving.

03-07-2013, 05:51 PM	#6
JesseE Senior Member Join Date: Oct 2012 Drives: LS Swapped BRZ Location: Phoenix, AZ Posts: 419 Thanks: 65 Thanked 173 Times in 90 Posts Mentioned: 30 Post(s) Tagged: 0 Thread(s)	100% normal :-)

03-07-2013, 06:37 PM	#8
Draco-REX Corner Junkie Join Date: Feb 2012 Drives: 13 BRZ, 11 STI, 99 RS Location: Ohio Posts: 2,908 Thanks: 129 Thanked 1,521 Times in 702 Posts Mentioned: 11 Post(s) Tagged: 0 Thread(s)	Completely normal. That pulley is mounted to a spring-loaded belt tensioner that's designed to keep the overall tension of the belt at a set point. As the engine goes through its cycles, and the alternator adjusts for loads, and other things occur, loads on the belt can change so this pulley will bounce, even rapidly as you're seeing, to maintain the proper tension. Automatic Belt Tensioners are used on MANY cars. It allows the engineers to design an accessory system that uses one LONG belt rather than multiple smaller ones. Otherwise you wouldn't be able to compensate for the changes in length and tension with such a long belt. It also reduces the time needed to change the belt since you can just swing the tensioner out of the way to remove the belt and put the new one on.

10-03-2013, 02:09 PM	#12
loogs Banned Join Date: May 2013 Drives: on cruise control Location: Long Island Posts: 618 Thanks: 234 Thanked 145 Times in 109 Posts Mentioned: 6 Post(s) Tagged: 0 Thread(s)	what do you guys think of mine? listen past the crickets, past the exhaust and past the pulley. theres a weird sound and its got me concerned. it only happens when i turn the AC on. [ame="http://www.youtube.com/watch?v=WjZHWAkhkFI&feature=c4-overview&list=UUL4djS2xrkT2ist4nlAvRMg"]Fa20 AC on - YouTube[/ame]

10-03-2013, 03:48 PM	#13
Razz Senior Member Join Date: Jun 2012 Drives: Fast Location: United States Posts: 480 Thanks: 64 Thanked 101 Times in 71 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	^ I hear the whistle. That needs to be lubed. The other clunking sounds wrong. Crickets are DI so that's okay. The other sound is like an echo between two metal pieces. However if it occurs when AC is turned on it is the compressor. And that's pretty loud for a compressor.

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