Will I ever enjoy this engine?!

[944Fripp]

Hi all,

I've just had all new clutch hydraulics on my S2 (slave, master and piping) and although it seems to have stopped the new clutch slipping (and looking at the colour of the new fluid, it really needed doing!!) at peak torque it now slips because the pedal sticks after a gear change!! AARRGGGHHH! Is this totally hopeless?! Am I ever going to be able to enjoy this engine?! Or is this normal for a new cylinder set, do the seals just need to ease up from new and bed in properly?!

Any answers gratefully received!

T (a frustrated petrol head).

 

[ukmastiff]

Thats not normal , at least it didn't do it when mine were changed. I had new clutch master / slave and piping and all was fine. Sorry I cant add more but I dont know more

Regards

Mas

 

[944psi]

Would be interested in the outcome of this.

I fitted a new clutch, flywheel, slave, master cylinders and release bearing, fork - the whole shebang, but even after that something wasn't quite right. Several bleeds and the pedal still dropped to the floor. No sign of any fluid leaks. Then it was in for an MOT at a specialist - they mentioned the clutch pedal - dropping to the floor occasionally. They bled it, still the same and then replaced the new slave cylinder that I had fitted as apparently it was leaking. The pedal hasn't dropped yet, but still has a bit of resistance coming back to its natural height. Makes me wonder if there is something that can be greased or adjusted on the clutch pedal itself. Didn't know if there was a spring on the pedal to assist in bringing it back?

Stick with the car though - it's part of the fun [] - sorting out all of the niggles. How much fun would you be having in a 59 plate Mondeo ...?

Phil
91 S2, Only one headlight works, cable tie on one fog light, rear hatch locks out of adjustment, calipers waiting to be rebuilt .... could go on.

 

[Hilux]

Most 944 owners dont know that the clutch pedal mount area on the front bulkhead in RHD cars is a known weak spot.

The bulkhead itself is prone to movement and cracking and is easily missd by MOT`ers

Check by viewing from inside the engine bay and watch for movement when someone presses the clutch and pray its ok or its an expensive welding/plating job.

If its not the mount etc moving and the pedal is still not returning then (I am not sure if there is one) is the return spring twisted/damaged/worn? If not then its the hydraulics and someone may have inadvertantly installed cylinder rubbers the wrong way. If the clutch pedal drops I`d say damaged/poor/wrongly fitted m/c or s/c rubbers as 100% the cause as the fluid will bypass them and allow the pedal to move with diminished resistance but resist movement the other way also

One aspect might be the clevis pin. Is the clutch pedal action linear with the m/c If not then is the pin binding? Is the clutch pedal bent? Is the clutch pedal bush worn? .

If a non OEM slave, is it like for like.

Did you replace the hoses? The top hose can airlock? Crack the joints at the m/c to bleed just like a bleed nipple (this also works for brakes) Also old hoses can delaminate inside and fluid gets behind the inner lining shutting the pipe off under pressure.

HTH and good luck.

 

[JM1962]

Bleeding the slave cylinder is not straight forward, you need to bleed it before it is fitted fully into position to make sure all the air is out, although I can't see how air in the system would make the clutch slip. Sound like something is sticking somewhere.

 

[pauljmcnulty]

Bleeding the slave cylinder is not straight forward, you need to bleed it before it is fitted fully into position to make sure all the air is out, although I can't see how air in the system would make the clutch slip. Sound like something is sticking somewhere.

Slave is one of the jobs I've done as a complete novice mechanic. I didn't do anything more complicated than follow the instructions, get the boss to pump the pedal until all the air was out.

I don't understand how the clutch would be slipping whether the hydraulics were working or not? When my pedal hit the floor it was total failure. To me, if the clutch is engaged enough to slip then the hydraulics have done their job engaging the clutch. The slipping is the fault of the clutch, or the associated bits.

It's not unheard of for the clutch pedal to stick. 99 times out of 100 it's the cylinders or the joining pipe, were they all replaced with new, official parts and bled properly? It should be fairly obvious if there's a mechanical problem with the pedal, from stuck carpet to failed bulkhead or distorted floor pan.

It might help if you list everything that's been done, what parts were used etc. I'm sure there's one obvious little problem that's causing you so much grief!

 

[JM1962]

Ok, bleeding the slave cylinder is simple if you follow the instructions. See clarks garage for how to do it. I still think its possible for the average (non Porsche or specialist) garage mechanic do it wrong and not get all the air out.

http://www.clarks-garage.com/pdf-manual/clutch-02.pdf

 

[944Turbo]

actually missed the slipping bit when I replied earlier - was working!, yes hydraulics unlikely to cause slipping - unfortunately more likely internal to the clutch - faulty pressure plate? or something else mechanical that stops the pedal returning.
Tony

 

[944Fripp]

Is a faulty pressure plate likely to make the pedal fall to the floor though? It get's better as the car warms up and the pedal rises after about 5 miles of driving. The pedal takes a while to raise still though.

 

[944Fripp]

Just a quick update: it got ridiculous!

I was trying to drive up a steep hill in Sheffield (of which there are many!!) after the car had been sat for a couple of days and could get only 15mph out of it before the clutch slipped. I did not have this problem before it went to the garage for the clutch hydraulics! So, I have given the car to the garage and asked them to use it (the guy looked very happy at this!) for a couple of days and please sort out the problem. I told him I suspect it either wasn't bled properly, there may be a problem with some kind of return spring on the pedal, the pedal itself may be preventing the clutch from engaging properly or all of the above, either way please sort!!

Will update as soon as I get the car back which I hope will be tomorrow afternoon.

In the mean time I have been doing a little research into how a clutch works (I'm a bit of a novice!!) which has settled my worries over it potentially being a faulty pressure plate as I don't really see how a faulty pressure would: a) be missed during both new clutch installations and b) cause the clutch pedal to fall when left over a long period. For me, this narrows it simply to hydraulics causing the pedal to fall) or the pedal sticking due to the mechanics that hold the pedal in place.

Please feel free to correct me if I'm wrong though!

 

[944Fripp]

I've now picked up the car from the garage and there's not the slightest hint of any slip! The pedal feels firm and springs back in an instant like a new car! Hooray! Basically the problem was in the adjustment of the push rods to the master cylinder. The margin for error on the adjustment screw is around 5mm from a certain point and it was not adjusted to this. To compound things there seemed to have been a stop missing on the upswing of the pedal. This has been "fashioned" by the mechanic and seems to work a treat! Problem solved...mostly. The pedal still sinks over night and raises again when the car is all warmed up after about 8 miles of driving. I can live with this but must admit I am a bit miffed!

I'm a complete novice with clutches but have come to understand that it consists of a pedal, linkages to the master cylinder, a pipeline filled with hydraulic fluid (and ONLY hydraulic fluid, no air), a slave cylinder at the other end of the pipe linked to a clutch fork which pushes the center of the thrust bearing into the center of a diaphragm spring. When the thrust bearing is pushed forwards it depresses the center of the diaphragm spring which because of the pins which hold the spring in place acts as a lever pulling the pressure plate backwards and with it the clutch plate from the flywheel; this disengages the drive to the gearbox. When you take your foot off the pedal, the thrust bearing retracts releasing the center of the spring, the outer edge of which forces the pressure plate back against the clutch plate and flywheel re-engaging the drive. Is this correct?!
Why then, does the pedal sink when the car is left for a while, and what causes it to raise again after the engine has warmed up?! The only thing I can think of is that some form of linkage is not working properly and the heat is freeing it all up. Maybe a grease build up? Maybe the system has not been bled properly but how does this explain the perfect operation except for when cold?!

Don't get me wrong, I can live with it, the car has always done this but it is most confusing!

Answers on a postcard!!

T (a much happier petrol head!)

 

[Dockrell]

Tom,
I now seem to drive automatics but have had manual cars in the past.

Could the problem be that the clutch reservoir cap is blocked in its air vent and not allowing fluid to refil the hydraulic pipe work.

Overnight as the fluid in the pipe cools the pedal is drawn down. Once the car is used the engine heat expands the fluid and raise the pedal.

If this is the problem if you undo the clutch reservoir cap in the morning you should hear air going in to the reservoir.

Mike

White 2.7 automatic

 

[944Fripp]

Great suggestion Mike and a completely new one on me! The car's been stationary for the day now and the pedal has fallen a bit. I just whipped the cap off, listening for any air being pulled in but nothing. I gave it a good clean anyway even though there was nothing obvious there. Maybe....just maybe!

Any more for any more?!

T