"chattering" noise coming from passengers side of engine compartment - any suggestions?

[lucky phil]

Can I ask please while we're on this topic so I don't open a new thread:

Can someone explain why the engine sound idling changes ever so slightly, (you can also feel the change in vibration in the cabin it very subtly) when you put the clutch in whilst in neutral?

No other manual car I drove does this, is it something to do with the software for the rev matching?

To be clear, this isn't an issue, it feels like that's how the car is designed to work but I'm curious to understand the mechanical reason(s) why.

When you disengage the clutch in neutral a couple of things happen. The crankshaft is loaded from the clutch pedal force and and the crank thrust bearing is now loaded. This is something you won't normally feel though. The main thing is there is a 3 pound clutch friction plate that's now stationary instead of rotating at engine rpm and the crank pilot bearing if it has one that supports the gearbox input shaft is rotating because the gearbox input shaft has stopped turning. So an Eagle arsed owner may feel slight differences in the Idle. Some cars have an Anti stall strategy where the ECU ups the engine speed without throttle input as you release the clutch also. The most common thing that's usually noticeable to the attuned person is generally the NVH and noise is reduced when you disengage the clutch due to the friction pate and gearbox now being stationary or very close to stationary. Those big gears in the gearbox designed to take 600ft/lbs or so of torque have mass and backlash and usually rumble away a little at idle with the clutch engaged and quiten down when you depress the clutch pedal as the gearbox stops rotating. More noticeable on a larger capacity 4 cylinder engine with inherently imperfect secondary balance. Not so much on an in line 6 with perfect primary and secondary balance.

Phil

Sponsored

 

[3TMagnetMan]

I must have used the wrong keywords, but even generic ones such as "chatter" "chattering" and "noise" didn't show anything within the past day, and back a few months the results returned weren't really relevant.




I've uploaded a video; Car is in neutral (6MT). AC off or on doesn't have any change to the sound, and pushing the clutch in doesn't either. You may have to turn the volume up to hear it well enough. I heard it on my headphones just fine but on my speaker it was hard to pinpoint, it resembles a chattering clutch or some kind of rattling, though.

Edit: website video uploader seems to be broken, had to go third party:

Sounds like my car lol. Open the hood and take the engine cover off sounds like a Diesel Engine lol.

 

[Supra_UK_]

When you disengage the clutch in neutral a couple of things happen. The crankshaft is loaded from the clutch pedal force and and the crank thrust bearing is now loaded. This is something you won't normally feel though. The main thing is there is a 3 pound clutch friction plate that's now stationary instead of rotating at engine rpm and the crank pilot bearing if it has one that supports the gearbox input shaft is rotating because the gearbox input shaft has stopped turning. So an Eagle arsed owner may feel slight differences in the Idle. Some cars have an Anti stall strategy where the ECU ups the engine speed without throttle input as you release the clutch also. The most common thing that's usually noticeable to the attuned person is generally the NVH and noise is reduced when you disengage the clutch due to the friction pate and gearbox now being stationary or very close to stationary. Those big gears in the gearbox designed to take 600ft/lbs or so of torque have mass and backlash and usually rumble away a little at idle with the clutch engaged and quiten down when you depress the clutch pedal as the gearbox stops rotating. More noticeable on a larger capacity 4 cylinder engine with inherently imperfect secondary balance. Not so much on an in line 6 with perfect primary and secondary balance.

Phil

Wow thanks Phil this is super interesting

 

[NocturnalEmber]

Just book the appointment. Bunch of people have said it's normal. Now you're just seaking responses to validate what you already think is an issue.

I'm not "seaking" responses to validate anything; My entire reason for posting was to gather information about my concern, and as it stands I never discounted the possibility of it being DI's, though I've never owned a car with DI that sounded quite like the noise I'm hearing.

Sounds exactly like mine and other friend's Supras. Been doing that sound since day one, and I'm at 15K miles.

Edit: would be nice if mods can make a "new supra owners" tab so that new users can see all the things that normal

Maintaining and working on cars isn't a foreign concept, and while having a section for new supra owners wouldn't likely be a bad idea for someone who also posts asking questions and hasn't modified a car before, that's a bit hypocritical to insinuate that I don't know what I'm talking about.

Translation = I already have my mind made up to go to the dealer to have them tell me the same exact thing everyone here is saying but I am ignoring, even though I asked for opinions.

Mistranslated, actually. You might as well apply that logic to every question asked on any automotive forum if you are trying to justify my thought process that way.

+
Owners know more about the car than the "I get a Supra to my dealer/service once a year" techs.. So I don't think service will be of help other than to have a knee jerk reaction of saying "it's normal"..

That would be why I posted on the forums first.

 

[M3ltdown]

Just book the appointment. Bunch of people have said it's normal. Now you're just seaking responses to validate what you already think is an issue.

 

[Spart]

That likely has to do with the “anti-stall” in the engine management. Don’t have a manual but willing to bet if you release the clutch slowly enough without giving it gas it’ll prevent itself from stalling. My 500 Abarth was like that.

I'd have to agree with this, though I haven't really borne the idea out, I've noticed the engine revs do weird things when you clutch in/out while in neutral. Seems a lot like anti-stall.

 

[calmeda1]

Maintaining and working on cars isn't a foreign concept, and while having a section for new supra owners wouldn't likely be a bad idea for someone who also posts asking questions and hasn't modified a car before, that's a bit hypocritical to insinuate that I don't know what I'm talking about.

When did I ever say that you don't know what you're talking about? :|

I'm saying that this car has a lot of noises, clunks, creaks and feel to it, even when brand new and stock, that may seem like something is wrong with the car when there's not. My suggestion was that it would be nice if the moderators posted all those noises and stuff that's normal to the car somewhere so that new users can see it and avoid a scare like a lot of us have. Reason why I say this is because I too have asked those questions at the beginning of my ownership of the car.

Sponsored