# 2.5L Engine slight knock at idle and slow speed



## sportshaggen (Aug 18, 2012)

Hi,

I have a 2010 JSW with the 2.5L gas engine and manual trans. It only has 25k miles, still under warranty. It has a noise that I am wondering about. It sounds like slight engine knock at idle and when first starting out in first gear or reverse. Kind of a "toc-toc-toc-toc" sound. Not a clicking or tapping noise. You can actually feel it in the shifter, too if your hand is on it and you are gently letting out the clutch. 

It is not a very noticeable sound, but I have been wondering about it as my warranty is getting close to the expiration date. The sound is always present at idle and when letting off the clutch in first gear or reverse. I don't notice it at higher revs (in gear or not). I haven't driven any other 2.5 VWs so I don't know if this is normal or not, but thought I would post in hopes that someone might have ideas. In general the engine runs and sounds great, economy is 25 town up to 34 hwy (I am not a speedy driver), check engine light has never come on. Always serviced at dealership and on time. 

The only thing I have noticed about the engine is that when you cold start it, the rpms go to 1700rpms or so and stay there for about 10 seconds until an audible hissing noise in the engine, then they go down to the regular idle speed. I have always assumed this is normal, but thought I would mention it too. 

I would make a recording of the knocking noise but the sound is really subtle, probably would not get picked up due to ambient engine noise. 

Thanks for any thoughts,
Alex


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## Lwize (Dec 4, 2000)

http://forums.vwvortex.com/showthre...-I-have-the-dreaded-Dual-Mass-Flywheel-rattle...

http://forums.vwvortex.com/showthread.php?5782035-09-Rabbit-idle-knock


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## sportshaggen (Aug 18, 2012)

Thanks. I have to say my noise is a lot like the sound of the DMF going bad. But... does the 2.5 gas JSW with 5sp MT have the DMF or a different flywheel setup?


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## mabbonizio186 (Oct 15, 2006)

the noise your care makes at idle when first starting is normal...

*Your car has a DMF*

On to the knock you describe. 

1. As someone posted above a link to my thread I just went through a trans related noise. The first step is to determine weather the noise is coming from the trans or motor, i'd say if you feel it in the shifter and only it happens in first and reverse it's prob trans related. 

2. Your car has a power-train warranty for 5 years or 50k so you have plenty of warranty left to stick vw with the repair bills if something is wrong with your drivetrain. 

3. From the research i've done, the flywheel set up used in these cars has proven to a be occasionally problematic. I just had my entire clutch/flywheel assembly replaced by vw for noises and while my dealership was great and gave me zero issues about it others have had more trouble since the clutch is a wear part. 

- if possible post a video clip of the noise so we can get a better idea of what your talking about. From what I've gathered SOME clutch/flywheel noise is okay/normal... excessive noise is not and can lead to premature failure of those parts. My clutch is still audible after replacement, but just barely if parked up against a wall, it engages much smoother, and the pedal just feels "right". 

good luck:thumbup:


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## rustlerdude (Aug 13, 2007)

It's completely normal to have some noise. The flywheel does move and will make a faint knocking or thumping noise with the c lutch out. If it's banging away, it's bad. It's hard to trust me, but you will KNOW when the dmf goes bad.


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## sportshaggen (Aug 18, 2012)

Thanks. I'm working on posting a sound clip. Video was really big (22 MB for a 1 minute clip.... thanks apple). 

I'm glad to know the drivetrain warranty is good through 5 yrs / 50k miles. I can imagine that some dealerships may not be very willing to cover clutch components though.


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## sportshaggen (Aug 18, 2012)

Here is a link to the sound clip. It is an m4a file, I opened it with quicktime but it should work with other programs I think. 

In the recording, I think the noise is most apparent starting about 20 seconds after starting the car, when I let the clutch out. The recording was made with my phone on the driver's side wheel.


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## mabbonizio186 (Oct 15, 2006)

I listened to your video.

As posted above it is normal to have some trans/ clutch noise. Even after my car was fixed it still makes a tiny but of noise when parked up against a wall or in a garage where the sound bounces off things.

However if your clutch pedal feels strange at all you should have it checked out. IMO your noise sounds more like a bearing (throwout?) than flywheel/clutch chatter as that is more metallic and yours is kind of soft. 

In the end it wont hurt anything to have it looked at. Like I said, while some noise is normal, I felt the noise my car made was too loud and thus not normal. The dealer who did the work on mine said they had replaced a few other 2.5 clutch/flywheels as well. 

Most importantly research the dealer you take it to before hand so you don't get the runaround if they have poor customer service. Find a good dealer and take the tech for a ride. I parked in between two parked cars in a secluded area for the tech to hear my noise. As soon as he heard it he said they would fix it asap.


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## sportshaggen (Aug 18, 2012)

Thank you very much for the detailed reply. I also found the thread on your experience very helpful. 

I agree with you that it sounds like a non-metallic soft thumping noise, not the metallic chatter I have heard on some other videos. 

As it is now, the clutch feels fine to me. My wife has complained that it is hard to feel the point where it engages and disengages compared to our previous cars, which I assume all had simpler single plate systems (old saabs and volvos). 

I am currently out of town for a couple of weeks with the car, but when I get back will go to the dealership in Seattle that we like. We've tried three different ones, and University VW seems to be the best. 

Cheers,
Alex


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