Weird sudden clutch slip

[2stis]

Hi all. Can anyone please help me by thinking of any fault that would cause the following symptoms:

Car ran fine when I last drove it - no sign of any impending issue. Parked it up and when I went to move it the next day the starter just whirred but did did not fire up. I removed the starter and found that the cog was not engaging. I think it was stuck on the shaft as I could not move it by hand and I think that probably broke the solenoid as it strained against it. I bought and fitted a new starter and the car then fired up first try.

I drove out of the driveway and onto the road. At that stage things appeared normal at slow speed but when I got to the road and tried to pick up speed the engine just revved with no change in momentum, as if the clutch were slipping. It was fine previous to the starter failure and due to a previous release bearing failure the clutch plate was replaced 3000 miles ago with easy driving since so can't see that suddenly expiring. There is also a strange behaviour in that if clutch pedal is fully down (normal) or up (not normal) there is no engagement but at around the usual biting point I am able to get some drive to move the car.

It would seem to be too much of a coincidence for two major faults to occur at the same time so can anyone think of a logical connection between those two issues and where I should be looking at next to cure the fault (hoping not to have to pull the box off again)

Thanks

[normalbloke]

Time to have a word with your chaps who fitted the clutch perhaps?

[2stis]

I fitted it. I've done a few thousand miles since with no problem. Seems odd it went from okay to completely slipping on the same day that the starter motor packed up, no?

[GreenV8S]

Clutching at straws (sorry!), if it is a cable operated clutch and the cable was dislodged during the starter motor replacement then it may not be engaging fully. Cable operated clutches are rare these days. Alternatively, if it has a hydraulically operated external slave and the slave had to be removed to get at the starter, it's possible the pushrod didn't seat properly in the actuator arm, or the arm itself was displaced from its pivot. These are both problems that might conceivably fix themselves if the pushrod/arm are able to drop back into place after fitting.

ETA: Also, do you know whether that model has a self-adjusting clutch?

Edited by GreenV8S on Wednesday 9th December 15:40

[2stis]

Appreciate you taking the time to reply. You've given me some things to consider there. It is a hydraulic clutch and I was considering trying bleeding that again just in case it makes any difference. There shouldn't be anything obviously dislodged during the starter motor change as the slave is internal to the gearbox (had to replace that months ago when it started leaking, which since it was a gearbox off job I stuck a new clutch in there whilst I was at it).

It is a self-adjusting clutch, if that has any bearing on what could go wrong?

Small world - I'm pretty sure our paths have probably crossed at a sprint/hillclimb!

[Boosted LS1]

OP are you saying that the previous starter didn't rotate the flywheel?

[finlo]

Starter motors dying these days is usually a precursor to DMF failure

[2stis]

Boosted LS1 said:

OP are you saying that the previous starter didn't rotate the flywheel?

Correct. When it went wrong that is. You could hear motor running but cog never engaged to turn flywheel. New starter now spins up the engine fine but I've now got a clutch problem that appeared just as suddenly!

[2stis]

finlo said:

Starter motors dying these days is usually a precursor to DMF failure

It has a DMF but my other cars don't so I am less familiar with them. What are the symptoms of a DMF failing please? Can they just suddenly fail?

[GreenV8S]

2stis said:

It is a self-adjusting clutch, if that has any bearing on what could go wrong?

I think there are a few designs for that, but they mainly involve adjusting the pivot point of the springs. The adjusters are designed to only adjust in one direction as they take up wear, but one failure mode is for the adjuster to slip. That may be more likely if the adjuster has not been reset during assembly so it isn't working in the normal operating range.

[gman88667733]

2stis said:

It has a DMF but my other cars don't so I am less familiar with them. What are the symptoms of a DMF failing please? Can they just suddenly fail?

DMF failure normally gives a horrible rattly noise at idle. Like a pebble in a washing machine from the gearbox area. Once you hear it once, you never forget it! Some don't make any noise at all though, so that's not a sure fire way.
Sometime excess vibration from the clutch pedal can be the DMF failing too.

[2stis]

Thanks for the replies all. Looks like it is gearbox off again this weekend then :-( I've done a bit of reading up and am a bit more familiar with DMFs now. I don't have that horrible clanking noise on mine. I can see how they could wear out so the two parts are no longer providing any damping effect with respect to each other but I can't see how that would result in movement in the plane that the clutch plate is operating in so is clutch slip definitely a known sympton of a duff DMF please?

[gman88667733]

2stis said:

Thanks for the replies all. Looks like it is gearbox off again this weekend then :-( I've done a bit of reading up and am a bit more familiar with DMFs now. I don't have that horrible clanking noise on mine. I can see how they could wear out so the two parts are no longer providing any damping effect with respect to each other but I can't see how that would result in movement in the plane that the clutch plate is operating in so is clutch slip definitely a known sympton of a duff DMF please?

I wasn't aware that a slipping clutch is a symptom of a failing DMF. Personally, if the only symptom is a clutch slip, then I'd point the finger at the clutch itself?

Without seeing/hearing/experiencing it, it is really hard to say for sure. Best practice is to change the DMF when the clutch is changed to avoid issues.

However, bad DMF's can and do wreck starter motors, so that is something that relates to yours potentially.
Was it is a decent brand of clutch you put in? I've heard of cheap ones being duds immediately and some only lasting a thousand miles or so.

[2stis]

The new clutch I fitted was a LUK, which is a 'quality' manufacturer present as OE by many manufacturers I believe. I was hoping that there might be some other straw to clutch (no pun intended) at of the cause of the problem of the clutch now slipping as opposed to having to take the box off again to investigate, which, as you can imagine, is a fairly time consuming job (and the new gearbox oil I put in with clutch change was £50!) but it doesn't sound like there is any obvious alternative/diagnosis I should be performing first so will just have to crack on I guess.

[2stis]

Thought I'd post the result in case of use to anyone else in the future... It was the DMF that was at fault. The inner friction face had become completely detached from the main mass of the flywheel, hence why there was no 'clanking' noise. I'm now surprised that it even had enough drive to move around the driveway but I presume the clutch plate clamping must have applied enough force to push the two broken parts of DMF together a bit.

[CrutyRammers]

Top marks for coming back to the thread with the outcome

[2stis]

New DMF has arrived. You can see the old one is missing the collar inside and I found a few bits of it in the bottom of the clutch housing.

[dhutch]

I had the option to replace the DMF or not when I had my clutch done, didn't know which way to go, ended up changing it.