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Pulsing Noise from Manual Transmission
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rayschoepfer
Novice
Nov 1, 2016, 1:53 PM
Post #1 of 10
(1898 views)
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Pulsing Noise from Manual Transmission
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Hi:
I have a 2012 Hyundai Elantra Touring 5sp manual with about 110,000 miles on it. In the last few months I started getting a pulsing sound that follows the engine in the 1500 to 3000 rev range, only when the clutch is engaged. I took it to the local mechanic who said he was not sure, thought it might be a bearing in the clutch assembly. Any ideas?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 1, 2016, 3:29 PM
Post #2 of 10
(1891 views)
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Re: Pulsing Noise from Manual Transmission
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Did this mechanic drive this and witness the noise and not sure or just not sure both?
I'm not convinced this is clutch or transmission at all so would rule out motor mounts and exhaust flex pipe if this only happens while driving not just revving engine.
Try this: Engine off - when cool enough grab tailpipe and shake the heck out of it to see if you can get a noise from exhaust parts or tap on exhaust parts with a rubber hammer and make a noise. If so chase down which item makes noise and where,
T
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rayschoepfer
Novice
Nov 1, 2016, 4:43 PM
Post #3 of 10
(1888 views)
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Re: Pulsing Noise from Manual Transmission
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Thanks for stab at it but this only happens when driving, not just revving engine. When I'm driving and push clutch the noise goes away, when I let clutch back in the noise is back.
Just came back from another mechanic who also said it's the clutch and should probably get whole clutch rebuilt.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 1, 2016, 10:52 PM
Post #4 of 10
(1877 views)
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Re: Pulsing Noise from Manual Transmission
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With noises it's impossible to compete with being right there and hard sometimes even then.
Clutch designs about all do NOT have a bearing to make noises when engaged at all. The highly routine way they work is a 'release bearing' also called a throw-out bearing isn't supposed to be turning when your foot is off pedal. There should and must be free play at top of pedal travel you should be able to push by finger about (rough amount average) one inch and never lose that while a load is on engine.
Another is a bushing that is turning only when clutch is pushed or disengaged that centers front shaft of transmission to crankshaft only when pushed and most usually when sitting still.
Other noise from a clutch assembly itself can only really be broken parts.
Almost all FWD based vehicles the engine is placed in sideways called transverse such that with a load it tilts some forward and backwards not side to side so exhaust and mounts must be ruled out as flex pipe and heat shields are VERY common. Aftermarket exhaust work or parts can rub and these things can make a wide range of noises usually at a certain load or RPM.
The front pipe(s) on many have to be removed or moved for certain other work perhaps quite a while earlier and stresses some parts as well that a problem shows up later.
Not convinced this has anything to do with clutch or transmission still. If you can't do a test with a rubber hammer yourself or nobody has been sure that's next.
Playing tag with your reports from another person's guess that so far isn't plausible is really not helping find this diagnosis difficult in person and lots harder second hand.
Nobody is sure but seems ready to blame a whole clutch and so far you aren't there yet. IMO this is still just a noise unknown not a transmission component anything only tied by the speed and load on the engine which many noises are going to be heard at,
T
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rayschoepfer
Novice
Nov 2, 2016, 8:34 AM
Post #5 of 10
(1870 views)
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Re: Pulsing Noise from Manual Transmission
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Thanks for the detailed response.
I'll spend some more time going over what you wrote here as the last thing I want to do if spend a bundle on rebuilding a clutch just to be faced with no change in problem.
And I agree that not being able to actually hear the sound makes things really tough to say.
Guess I'm off to learn a lot more about clutches 
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 2, 2016, 10:34 AM
Post #6 of 10
(1867 views)
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Re: Pulsing Noise from Manual Transmission
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Typical automotive clutch design.....
Picture>
^^^^ Was there may disappear?
"THE" bearing in the whole thing is shown called "Throw-out bearing." That pushed on the pressure plate assembly to DISENGAGE the clutch from the turning flywheel which is the speed of the engine. Not shown is the front, splined shaft of transmission which goes thru this whole mess and is really just centered to be held inside the "Pilot Bushing."
All that stuff turns at the speed of the engine when you take your foot off the pedal - "Disengaged" even the throw-out bearing is just idle then and shouldn't be touching the pressure plate.
Now, if you said it made noise WHEN pedal is pushed down OR "Disengaged" the throw-out bearing is turning at the speed of the engine. Got it?
So you've said it "shut up" when you have the only bearing in this mess working so that's why this probably isn't your noise.
Sorry for the novel but your description and tech's right there listening if so can't say anything but replace all that stuff? NO! It would somehow have to have broken parts flying around or something?????
If I misunderstood you and what they suggested I'm sorry. This is how it works - about all ever made use this design.
My suggestion is get someone to witness this who has a clue how this works as if what you said nobody does yet.
Have you tapped on exhaust parts yet? NO - you haven't have you? That's 1,000 times more likely than the clutch making a noise when you said,
Tom
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rayschoepfer
Novice
Nov 16, 2016, 10:01 AM
Post #7 of 10
(1844 views)
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Re: Pulsing Noise from Manual Transmission
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Hi Tom:
Sorry for the long gap before replying.
Thanks for all the info. I think I now understand how the clutch system works from all your info (great!!) And I agree that it can't be the "throw out bearing".
I have not had a chance to climb under the car and check the exhaust, that is next. Hopefully it is something like that as opposed to something broken and floating around in the transmission.
Thanks for all your great help.
Ray
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 16, 2016, 10:36 AM
Post #8 of 10
(1843 views)
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Re: Pulsing Noise from Manual Transmission
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A "key" comment is it's under load (clutch engaged) at a certain RPM or level of load. That so strongly puts this on exhaust bullcrap first. Right from engine exhaust is routed funky and heat shields cheaper than cheap junk most just spot welded on which makes them WEAKER there oddly. Engines "torque" on rubber mounts with transmission as well put a load on my term "sideways engines" front to back NOT tilting left to right under loads which is has to.
Side note: RWD can twist an entire exhaust so you about never need then a flexible pipe of mesh that also seals and may be covered some with more shields.
That takes a real stress on those, gaskets and or how bolted in right at necks.
So, if mounts allow too much motion even if not broken there's too much at the certain load.
This is wildly common to me and trying like heck to retire as sign off says but still get the screaming about this stuff and softie (I am) goes out and fixes it.
It's also the salt belt capital of the world from MA in particular. World's worst drivers, horrible roads but folks insist that no matter what dang snow or ice happen or how fast the roads be plain wet all the time. Battery acid isn't that destructive!
Side tracked suggestion unknown if 100% "cricket" (local speak for legal) use stainless steel dryer vent clamps is shields vs tossing out sometimes a pipe with maybe even two converters over a flipping spot weld! Worm clamps I'll call them. Keep a dozen in stock now and quit doing this crap - laugh.
Sorry - off on this because it's so common to me. Heat shields are necessary so good to catch them before missing if so at all.
Tap, tap, tap on exhaust parts, rubber hammer you can find which one(s) easily usually still mostly intact. Clamp those tight enough with the clamps mentioned and I never see that come back again.
At least rule it out. That won't set codes, can make noise like all hell broke loose or just annoying as probably already said. Many you don't need to even hoist a vehicle and know that's what you'll be looking for, engine off and cool even. Try it.
Can't quit: BTW those worm clamps if same brand you can go end to end using more than one and get them neat and tidy - IMO stronger and last longer than new (sometimes) and still do their job,
Tom
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rayschoepfer
Novice
Nov 18, 2016, 8:22 AM
Post #9 of 10
(1827 views)
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Re: Pulsing Noise from Manual Transmission
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Hi Tom:
Got a chance to speak to my ex-mechanic who always impressed me with his knowledge and taught me about everything that effected me (we both moved, but to different places). He is on the same page as you. He thinks that it could be engine mount related. I'm currently away from my place on vacation so will be doing a thorough inspection of the underside when I get back home.
Thanks for all your info and saving me a bundle on unneeded work. If we ever meet, the beer is on me
Thanks
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 18, 2016, 8:55 AM
Post #10 of 10
(1825 views)
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Re: Pulsing Noise from Manual Transmission
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OK - Better with a helper and being VERY careful. Open hood and watch from side of car not in front. Have a driver with a clue nudge forward then reverse fighting known good brakes and watch the mounts move and lift or just stretch some as designed.
From the side is so if all goes wrong you aren't in front of the thing and get run over! If worried don't do that yourself at all,
Tom
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