Mystery death rattle?

[Alexander B]

I’ve already asked this one for ETCG Answers Questions Live, but I’ve not yet managed to fix it.

I’ve got a 2002 Renault Mégane with an 1.6 16v (twin cam, no VVT) engine, and it’s developed a mystery ticking/clicking noise.
It sounds kind of like a valve tick, but (to my ear) the speed of the ticking seems independent of RPM.
I can only hear it under more or less steady state cruising load, it goes away at Idle/unloaded, decel or hard(er) acceleration.

Its difficult or impossible to reproduce the noise at a standstil, do you have any tips for finding/diagnosing the noise?

Eric replied with some possible causes:
– Look at the FAQ for extra tips
– Detonation
– Timing chain slap + explanation

So far I’ve:
– Checked the FAQ, it doesn’t really match any of the showcased issues.
– Pulled out the new the spark plugs and put the old ones back in, the plugs that I took out didn’t show any obvious signs of detonation.
– The engine is fitted with a timing belt and is tensioned mechanically with an eccentric pulley only (no sping or hydraulic). Its on my to-replace list, but its buried really deeply in the engine, the timing belt cover is also the engine mount, and the valve cover is also the cam bearing caps, so its all very hard to take apart to even look at, stupidly complicated compared to most other brands, but thats another topic.
-Managed to reproduce the noise at a crawling speed (first gear idle RPM), it turns into a really slow tick-tick-tick, so its speed- or RPM- related.
– If I drive at a constant speed that presents the noise, and carefully press the clutch pedal to the point where it starts slipping and the engine revs up, the ticking noise stays constant speed.

So to sum op what I think/know so far.
– Noise doesn’t always present itself.
– Noise doesn’t come up at a standstill, or with the clutch depressed
– Noise goes away when I load up the drivetrain with either acceleration or engine braking.
– Noise seems to be related to engine RPM, its a slow tick-tick-tick at 750 RPM and a fast tick (trrrr) between 2000 and 3000 RPM
– Noise seems unrelated to engine RPM, it speed remains constant if I slip the clutch while its making the noise.
– There seems to be a soft chirping/chattering noise at idle (not always, but it seems to be getting more pronounced lately), I was thinking the acc belt, but apparently a clutch disk can make that noise too. [edit:] also makes the chatter with clutch pedal pressed, so thats just the acc belt that needs attention.

My conclusion: Clutch disk springs? I replaced the darn thing like 2 months ago when I had to replace the flywheel on an unrelated matter, but it fits pretty much fits the bill for all those combined things. Can clutches actually rattle though?

Topic

[college man]

The noise does seem clutch related according to your description.

[Alexander B]

[video]https://www.youtube.com/watch?v=Ydsk3-xmhj8[/video]
Recorded some of it, the microphone actually picks it up over the road noise.

Another idea I had was maybe the evap solenoid? I could test it if I could figure out how to unplug it.

[Mike]

If you place your foot on the clutch pedal, without putting pressure on the pedal/linkage, do you feel any vibration when the noise is present?

Are there any thin sheet metal access panels at the bell housing and starter area? The rattle also reminds me of loose metal vibrating against bolts that aren’t completely snug.

[Alexander B]

I don’t feel any particular vibration though the pedals or gearstick that coincides with the sound. I’ll try again tomorrow, but I don’t think so.

No inspection hatch or cover plate or any other sheetmetal I can think of, but I could check that all the bolts around the bell housing and gearbox are still tight.

I’ll also try unplugging the evap valve..

[Author]

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