What's with dual mass flywheels?

[Darragh]

I have just been told that I should have my dual mass flywheel and possibly clutch replaced. I have a 2010 2.0TDI 170 bph. I have 118k Km's (73k miles) on the clock. I was not expecting this. The mechanic said it is making noise. I can't hear it but I trust him implicitly, I've used him for years. Is this normal or am I just unfortunate? Any comments and thoughts here? Many thanks.

[AJB1]

I have a 2009 2.0 170 and mine had to be replaced a couple of weeks ago @ 78,000 miles.

If it is failing you might here it as the engine starts and you will almost certainly hear it when you switch the engine off, especially if you are outside the car or have the window open. The sound is some metallic "clanks" as the engine comes to a stop and, once heard, is distinctive.

If it making the noise then you need it replaced. Some types (I don't know about this one) can fail leaving you with no way of starting the engine and no drive even if you can. Apart from that, if it has worn to the point where it is making noises then it is no longer doing its job, it will be allowing torsional vibrations from the engine through to the gearbox and they will be doing harm there - increase wear of the clutch gears, synchro and differential.

The purpose of the DMF is because the diesel engine can produce very sharps "peaks" in torque - which appear as torsional vibrations - if you analysed the rotational force from the engine it would have regular sharp "grabs" in it.

When it is working correctly your gear changes will be smoother as will pulling away. Most of the wear is done when pulling away from standstill so it is how much of that you do (and your driving style) which determines the life. I have been told that failing at around 75,000 miles is very typical for a Superb 170 that has had "fairly normal usage". 

A faulty clutch that does not engage cleanly will increase the wear on the DMF, a faulty DMF will increase clutch wear considerably. A clutch which is slipping can overheat the DMF and that rapidly cause failure. 

Because of the above, because you actually have to remove the clutch to replace the DPF and the labour of dismantling and reassembly is a large chuck of the cost of replacing a clutch, and because a clutch which has done 75k is almost certain to be significantly worn - you would be mad to have the DPF replaced and then refit the old clutch - replace it at the same time.

The cost of my new DPF at a Skoda Dealer was around £1300. I have a Warranty with Warranty Direct who do cover DPF failure, unless the DPF failure was caused by a clutch failure. Warranty Direct covered all the labour and 70% of the price of the DPF parts, less a £50 excess. This meant they paid about £800 of the £1300 bill. Note I get a new clutch out of that. Not too bad overall. 

A. 

 

[Damo]

I have a 2009 2.0 170 and mine had to be replaced a couple of weeks ago @ 78,000 miles.

If it is failing you might here it as the engine starts and you will almost certainly hear it when you switch the engine off, especially if you are outside the car or have the window open. The sound is some metallic "clanks" as the engine comes to a stop and, once heard, is distinctive.

If it making the noise then you need it replaced. Some types (I don't know about this one) can fail leaving you with no way of starting the engine and no drive even if you can. Apart from that, if it has worn to the point where it is making noises then it is no longer doing its job, it will be allowing torsional vibrations from the engine through to the gearbox and they will be doing harm there - increase wear of the clutch gears, synchro and differential.

The purpose of the DMF is because the diesel engine can produce very sharps "peaks" in torque - which appear as torsional vibrations - if you analysed the rotational force from the engine it would have regular sharp "grabs" in it.

When it is working correctly your gear changes will be smoother as will pulling away. Most of the wear is done when pulling away from standstill so it is how much of that you do (and your driving style) which determines the life. I have been told that failing at around 75,000 miles is very typical for a Superb 170 that has had "fairly normal usage". 

A faulty clutch that does not engage cleanly will increase the wear on the DMF, a faulty DMF will increase clutch wear considerably. A clutch which is slipping can overheat the DMF and that rapidly cause failure. 

Because of the above, because you actually have to remove the clutch to replace the DPF and the labour of dismantling and reassembly is a large chuck of the cost of replacing a clutch, and because a clutch which has done 75k is almost certain to be significantly worn - you would be mad to have the DPF replaced and then refit the old clutch - replace it at the same time.

The cost of my new DPF at a Skoda Dealer was around £1300. I have a Warranty with Warranty Direct who do cover DPF failure, unless the DPF failure was caused by a clutch failure. Warranty Direct covered all the labour and 70% of the price of the DPF parts, less a £50 excess. This meant they paid about £800 of the £1300 bill. Note I get a new clutch out of that. Not too bad overall. 

A.

Great reply and lots of good info...

Just worth pointing out you start calling the DMF a DPF towards the end which is of course the Diesel Particulate Filter

[Noddy90]

You can easily tell if it's the DMF: start the engine in neutral and then lightly press on the clutch pedal, just sufficient to start to disengage the clutch.  If your DMF's going, you will hear a whirring/clicking sound that stops when you either release or fully depress the pedal.

 

HTH.

[pleasure]

My 2012 170cr estate had the clutch & flywheel replaced at 40k miles - handy coz I boutght it with 44k miles!

 

No idea why it was done though.

[Darragh]

Thanks for all the comments. Very helpful. I am listening for noise and think I hear it now. Will book it in I guess and get the cheque book ready!

[Devon Wanderer]

Is this just a manual gearbox issue, or are DSG boxes equally prone?

[littleade]

In 1 of the threads I've read previously on DMFs it was said that accelerating fairly hard from low revs increases the load on the DMF and reduces it's life, as does switching the engine off with the clutch pedal in the normal position with the car in neutral.