Engine Vibration Diagnosis

[rraghvani]

Audi S3 8L (BAM Engine) 52 Plate Revo State 1. Was driving along the M25 and shifted down to 5th gear to overtake a vehicle, as I then shifted to 6th gear the clutch pedal felt very spongy. I got caught in traffic, and had to turn the engine off. After about 30 minutes, I turned the engine on, and the car started to vibrate quite badly and I had thought I had blown one of my coil packs. Got back home, I revved the engine between 1000 and 2000 rpms, and the whole car started to shake really bad, loads of vibration through the steering wheel too.

• I’m convinced that my BERU coil packs are ok (only 6 months old), they don’t smell burnt.
• I removed each connection from the coil packs, engine idled roughly, as you would expect from a blown coil pack.
• Spark plugs are only 2 months old, had a little spec of oil on one of them.
• I serviced the car 1 month ago, plenty of oil, marked on the maximum of dipped stick.
• Engine management light is off.
• There’s no egg smell or white/blue smoke from exhaust
• Revving past 2000 rpms, engine smooth’s out.
• Holding clutch pedal down (still feels spongy) while revving engine, engine still vibrates between 1000-2000 rpms (Clutch master cylinder was replaced few years ago)
• I have suffered from clutch slippage for the last 4 years, but that’s intermittent.
• Engine mounts & dog bone mount looks ok too.

From the above symptoms, do you reckon I’ve knackered my dual mass flywheel?

Do you have a possible idea as to what the issue might be?

Thanks.

 

[gary3306]

I reckon you've definately got a fuffed DMF mate.

 

[pj123]

Or dodgy clutch slave cylinder leaking fluid, causing clutch slip and not pushing clutch plates apart fully...

I would start by bleeding clutch slave as thats easy and rules out air in the line giving the dodgy pedal feel.

Is there a rough idle both at a standstill and at speed (i.e. when gearbox is driven by the car freewheeling)

 

[rraghvani]

Clutch pedal and leaking slave cylinder I’ve always suspected with clutch slippage, which I lived with for four years!

Main concern is the engine vibration – whether in gear or not, engine will vibrate between 1000-2000 rpm (but less noticeable when in gear though), after 2000 rpm, it tends to smooth out, i.e. less vibration. The symptoms are similar to a washing machine.

 

[rraghvani]

After working on my car the last four weekends, I've managed to replace my dual mass flywheel, clutch plate, pressure plate and concentric slave cylinder. Engine vibration was caused by the flywheel, friction plate was off centred:






And the clutch slippage was caused by a leaking concentricslave cylinder:



I was quite surprised to see that the clutch plate had a lot of friction material on it, and that the flywheel and pressure plate didn't have any blue scoring marks – even though I drive fast, and used to do launch control.


Thanks for your help.

 

[s3dave]

How can the friction plate go off center?

 

[rraghvani]

I think the part in the middle, as highlighted, is possibly bent. I’m going to take apart my flywheel, and see what the actually issues is, and will provide photos.



Similar symptoms documented here VWVortex.com - Problems Resolved: Dual Mass Flywheel Vibration and Clutch Throw out Bearing / Slave Cylinder

 

[s3dave]

I had this problem a couple of years ago, it was always around 1500 rpm it seems to be ok now though... same flywheel etc..

 

[rraghvani]

Eventually it will give way. From all the stories I’ve read, it seems to be a common fault, even on new vehicles too. That’s why most people go for single mass flywheel instead.