Why would this happen?

[deadmau5]

I've got an '03 MR2. Occasionally when I accelerate in gears 3-6, the clutch seems to slip, but then I can lift off and then accelerate again, and the car will accelerate as normal. I've searched for these symtoms online, but can't find why a clutch would appear to slip sometimes, but then sometimes not. It is my understanding that when a clutch starts slipping it will do it all the time.

I have tried pulling away from stationary with the handbrake on and it doesn't slip, and the biting point seems fine to me as well.

Anybody got any ideas?

[Marf]

If its not consistently slipping then a dodgy clutch master cylinder would be my bet.

[mnkiboy]

I had a Fiat Punto that did that. Ended up needing a gearbox rebuild. When the drive was re-gained, it came with a crunch at the same time.

[LuS1fer]

I've had intermittently slipping clutches before it eventually slips all the time. How many miles on it?

[freecar]

Right, the definitive answer on clutch slippage.

Drive along around 35-40 in top (very low revs) for a few minutes without using the clutch pedal. Now floor the accelerator, if the engine speed picks up quicker than the road speed then the clutch is slipping. If it just accelerates slowly as it should then there is another fault.

Now, sit with your foot on the clutch for a couple of minutes, when you release the pedal if it comes up nicely ok, if it doesn't come up as quickly as it should there is fluid leaking past the seal in one of the cylinders. This fluid stops the piston from fully retracting when needed and this takes a few moments to return, so when accelerating hard you operate the pedal a number of times putting more and more fluid the wrong side until slippage, let off and wait for a second the fluid returns and the clutch fully disengages.

Does that make any sense?

[deadmau5]

freecar said:

Right, the definitive answer on clutch slippage.

Drive along around 35-40 in top (very low revs) for a few minutes without using the clutch pedal. Now floor the accelerator, if the engine speed picks up quicker than the road speed then the clutch is slipping. If it just accelerates slowly as it should then there is another fault.

Now, sit with your foot on the clutch for a couple of minutes, when you release the pedal if it comes up nicely ok, if it doesn't come up as quickly as it should there is fluid leaking past the seal in one of the cylinders. This fluid stops the piston from fully retracting when needed and this takes a few moments to return, so when accelerating hard you operate the pedal a number of times putting more and more fluid the wrong side until slippage, let off and wait for a second the fluid returns and the clutch fully disengages.

Does that make any sense?

Thanks freecar, I tried both of these but neither would appear to be the issue. After much digging on the internet, I heard that it could be oil getting on to the clutch, and when it 'slips' the oil burns off and when you press the accelerator again, the clutch has a better grip. Would this make sense? Has anyone experienced this before?

[Rubin215]

deadmau5 said:

freecar said:

Right, the definitive answer on clutch slippage.

Drive along around 35-40 in top (very low revs) for a few minutes without using the clutch pedal. Now floor the accelerator, if the engine speed picks up quicker than the road speed then the clutch is slipping. If it just accelerates slowly as it should then there is another fault.

Now, sit with your foot on the clutch for a couple of minutes, when you release the pedal if it comes up nicely ok, if it doesn't come up as quickly as it should there is fluid leaking past the seal in one of the cylinders. This fluid stops the piston from fully retracting when needed and this takes a few moments to return, so when accelerating hard you operate the pedal a number of times putting more and more fluid the wrong side until slippage, let off and wait for a second the fluid returns and the clutch fully disengages.

Does that make any sense?

Thanks freecar, I tried both of these but neither would appear to be the issue. After much digging on the internet, I heard that it could be oil getting on to the clutch, and when it 'slips' the oil burns off and when you press the accelerator again, the clutch has a better grip. Would this make sense? Has anyone experienced this before?

Yes, but with a VW camper...

Flywheel seal was weeping slightly, and oil was creeping along to contaminate the clutch.

Exactly the same symptoms, up until I had the engine out and changed the seal to stop the Exon Valdiz style oil stains on my drive.

[jayfish]

freecar said:

Right, the definitive answer on clutch slippage.

Drive along around 35-40 in top (very low revs) for a few minutes without using the clutch pedal. Now floor the accelerator, if the engine speed picks up quicker than the road speed then the clutch is slipping. If it just accelerates slowly as it should then there is another fault.

Now, sit with your foot on the clutch for a couple of minutes, when you release the pedal if it comes up nicely ok, if it doesn't come up as quickly as it should there is fluid leaking past the seal in one of the cylinders. This fluid stops the piston from fully retracting when needed and this takes a few moments to return, so when accelerating hard you operate the pedal a number of times putting more and more fluid the wrong side until slippage, let off and wait for a second the fluid returns and the clutch fully disengages.

Does that make any sense?

surely 35-40 in sixth isn't anywhere near the peak torque and this is where clutch slip is most likely to manifest.

[davepoth]

jayfish said:

surely 35-40 in sixth isn't anywhere near the peak torque and this is where clutch slip is most likely to manifest.

Clutches are self adjusting, right up until the point that they will go from working to not at all in a few miles, so by definition if the problem is that the clutch plate is knackered, rather than the self adjustment, you need to test it at the absolute minimum torque possible. If it slips in top then it's definitely the clutch plate itself that's worn. If it doesn't then the problem is elsewhere.