Symptoms of dual mass flywheel failure
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At least for a VW, if you leave the engine running, and open the hood, if you hear something like marbles being rattled around in a tin can, then that is the warning. I don't recall any change in how it drove (jerkiness).
Not sure if a Sonata would have the same failure mode.
Not sure if a Sonata would have the same failure mode.
Originally Posted By: supton
At least for a VW, if you leave the engine running, and open the hood, if you hear something like marbles being rattled around in a tin can, then that is the warning. I don't recall any change in how it drove (jerkiness).
Not sure if a Sonata would have the same failure mode.
Good call. Very often, dual-mass flywheels are used to mask gear rattle in the transmission. In those applications, it's probably not uncommon to get a rattle if the flywheel's damping mechanism is badly worn.
At least for a VW, if you leave the engine running, and open the hood, if you hear something like marbles being rattled around in a tin can, then that is the warning. I don't recall any change in how it drove (jerkiness).
Not sure if a Sonata would have the same failure mode.
Good call. Very often, dual-mass flywheels are used to mask gear rattle in the transmission. In those applications, it's probably not uncommon to get a rattle if the flywheel's damping mechanism is badly worn.
Originally Posted By: d00df00d
Originally Posted By: supton
At least for a VW, if you leave the engine running, and open the hood, if you hear something like marbles being rattled around in a tin can, then that is the warning. I don't recall any change in how it drove (jerkiness).
Not sure if a Sonata would have the same failure mode.
Good call. Very often, dual-mass flywheels are used to mask gear rattle in the transmission. In those applications, it's probably not uncommon to get a rattle if the flywheel's damping mechanism is badly worn.
Have never heard that about a DMF.
Can you give me a pointer on a source to read up about that? As I have only read that DMFs are used to make vehicles smoother, especially on diesel cars which is the first kind of vehicle I owned that came with a DMF.
I read in the Handbook for my 05 Mondeo 2.0 Tdci that you should always start and stop a DMF equipped vehicle with the clutch depressed.
Originally Posted By: supton
At least for a VW, if you leave the engine running, and open the hood, if you hear something like marbles being rattled around in a tin can, then that is the warning. I don't recall any change in how it drove (jerkiness).
Not sure if a Sonata would have the same failure mode.
Good call. Very often, dual-mass flywheels are used to mask gear rattle in the transmission. In those applications, it's probably not uncommon to get a rattle if the flywheel's damping mechanism is badly worn.
Have never heard that about a DMF.
Can you give me a pointer on a source to read up about that? As I have only read that DMFs are used to make vehicles smoother, especially on diesel cars which is the first kind of vehicle I owned that came with a DMF.
I read in the Handbook for my 05 Mondeo 2.0 Tdci that you should always start and stop a DMF equipped vehicle with the clutch depressed.
Originally Posted By: bigjl
Originally Posted By: d00df00d
Originally Posted By: supton
At least for a VW, if you leave the engine running, and open the hood, if you hear something like marbles being rattled around in a tin can, then that is the warning. I don't recall any change in how it drove (jerkiness).
Not sure if a Sonata would have the same failure mode.
Good call. Very often, dual-mass flywheels are used to mask gear rattle in the transmission. In those applications, it's probably not uncommon to get a rattle if the flywheel's damping mechanism is badly worn.
Have never heard that about a DMF.
Can you give me a pointer on a source to read up about that? As I have only read that DMFs are used to make vehicles smoother, especially on diesel cars which is the first kind of vehicle I owned that came with a DMF.
I read in the Handbook for my 05 Mondeo 2.0 Tdci that you should always start and stop a DMF equipped vehicle with the clutch depressed.
Your response made me realize that I had worded part of my post clumsily. Let me try again.
The point of a DMF is to damp vibration. In doing so, yes, it helps make the vehicle smoother. That's probably the primary benefit.
Some cars also have a lot of gear lash in the transmission -- enough to make noise if solidly coupled to the engine. The vibration damping effects of a DMF will reduce that noise. Thus, if the DMF fails (or is swapped out with a SMF), it's possible that the noise will return.
My old '95 Maxima had a SMF and no gearbox rattle. My '96 M3 had a DMF; if I had swapped it for a lightweight SMF, it would have made loud gear rattle.
Originally Posted By: d00df00d
Originally Posted By: supton
At least for a VW, if you leave the engine running, and open the hood, if you hear something like marbles being rattled around in a tin can, then that is the warning. I don't recall any change in how it drove (jerkiness).
Not sure if a Sonata would have the same failure mode.
Good call. Very often, dual-mass flywheels are used to mask gear rattle in the transmission. In those applications, it's probably not uncommon to get a rattle if the flywheel's damping mechanism is badly worn.
Have never heard that about a DMF.
Can you give me a pointer on a source to read up about that? As I have only read that DMFs are used to make vehicles smoother, especially on diesel cars which is the first kind of vehicle I owned that came with a DMF.
I read in the Handbook for my 05 Mondeo 2.0 Tdci that you should always start and stop a DMF equipped vehicle with the clutch depressed.
Your response made me realize that I had worded part of my post clumsily. Let me try again.
The point of a DMF is to damp vibration. In doing so, yes, it helps make the vehicle smoother. That's probably the primary benefit.
Some cars also have a lot of gear lash in the transmission -- enough to make noise if solidly coupled to the engine. The vibration damping effects of a DMF will reduce that noise. Thus, if the DMF fails (or is swapped out with a SMF), it's possible that the noise will return.
My old '95 Maxima had a SMF and no gearbox rattle. My '96 M3 had a DMF; if I had swapped it for a lightweight SMF, it would have made loud gear rattle.
Gear lash is an interesting point.
I didn't cut apart the flywheel, only saw it, when it came out. Looked like some valve springs in it. And the clutch mating surface and the ring gear for the starter seemed... loosely joined, if I recall correctly. Even if the mass was not in series with the flow of power, broken springs would mean that the mass(es) would be freely hanging. On an I4, with its un-smooth power delivery, the engine is constantly speeding up/down on each revolution--thus that mass would be shaking back and forth.
That's why I think it rattles in neutral. Not from gear lash (although it's possible) but rather from the weights banging around once the springs quit.
*
Besides, I read the bit about the "marbles in a tin can" on the web, so I know that's true.
The source was credible; and when my DMF came out, it clearly had something wrong with it. At least on the TDI's it was not unknown for a DMF to catastrophically fail: the car might no longer move, the car might be stuck in gear, or it might crack the bell housing. It was not something to be ignored.
I didn't cut apart the flywheel, only saw it, when it came out. Looked like some valve springs in it. And the clutch mating surface and the ring gear for the starter seemed... loosely joined, if I recall correctly. Even if the mass was not in series with the flow of power, broken springs would mean that the mass(es) would be freely hanging. On an I4, with its un-smooth power delivery, the engine is constantly speeding up/down on each revolution--thus that mass would be shaking back and forth.
That's why I think it rattles in neutral. Not from gear lash (although it's possible) but rather from the weights banging around once the springs quit.
*
Besides, I read the bit about the "marbles in a tin can" on the web, so I know that's true.
Valeo makes a replacement for a DMF that supposedly works and is cheaper/more reliable.
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