Thanks to everybody who responded to my queries about clutches and aircons. I have tried a C2 this weekend and my clutch (pressure plate) is definitely gone. There is no slip but actuating it is way too heavy. The C2 that I tried felt like
my 944S2, smooth and easy.

This means I have to take the thing apart to
determine the root cause. Can anybody tell me
if I can take the engine out of C4 and leave the gearbox in the car? I don't want to take the gearbox out because as far as I know there are some high pressure hydraulic lines connected to it and bleeding this system is supposed to be a problem.

I was at the official Porsche Centre in Lyon this weekend and they told me that you can remove the gearbox on a C4 and leave the engine in the car. As far as I know this is not possible. Any comments?

Thanks again, this forum is really helpfull,

Paul

 

Paul;

You do not want to attempt to take just the tranny out on your C4 for your first time. It will be much easier to drop the combo. A side benifit is to replace some engine seal (power steering seal & belt), valve adjust and so on.

 

Dear Paul,
You have a C4. The engine and transmisison comeout as one. No choice. It is not possible (normal conditions)to leave the transmission installed and just remove the engine. You have to drop the lot,
Ciao,
Adrian
911C4

PS: I should remind you that a C2 is not the comparison I would use. A 1989 3.2 Carrera yes but not a C2. Why? the 1989 C4 has a different flywheel/clutch set up to the C2. The C2 has a vacuum boosted hydraulic system (so does the 3.2 I know) whereas the C4 has a 180bar hydraulic pressure system. I am not saying your diagnosis is wrong but a heavy clutch pedal feel would not be sufficient for me to drop the engine and gearbox to decide the clutch plate is gone. Believe me when the clutch plate is gone in a C4 you can hear it, smell it and feel it.

 

Hi Adrian,

According to the Porsche PET CD the C2 and C4 have the exact same clutch (clutch plate/pressure plate). Even the hydraulic circuit for the clutch is the same. I agree that the hydraulic circuit for the brakes is quite different. I am pretty sure that the clutch plate itself is OK, it's the pressure plate that is bad. I will let you know what I find once I have removed everything.

Thanks,

Paul
ps. Have you ever dropped the engine/gearbox on your C4 yourself? Is there any interest if I take picture from the project and put them on a website?

 

I for one would be very interested in seeing photos.

 

ME TOO! Specifically, I want to know how to disconnect the hydraulc lines that run under the thing without opening them! The factory shop manual addresses this, but is clear as mud!

 

As would I. !

Regards

 

Dear Paul,
I would recommend you use the maintenance manuals for repairing a C4 and not the PET CD. I also recommend you wear safety glasses because I have a feeling you are going to see some spraying brake fluid. Good luck I hope it all works out for you.
I also checked your comments about the PET Cd and the C4 and C2 clutch assemblies. Firstly the 1989 clutch assembly is not even mentioned. I would advise you check part numbers on the removed parts first. The release bearing for the 1989 Clutch assy is a different part number. The alternative part numbers may be usable but take care because the G64 transmission does not get a mention. Whether you take the advice or not is purely up to yourself. However I warn you as a 1989 C4 owner myself. The parts catalogue misses out the 1989 C4 a number of times and using C2 parts on the assumption that they will fit can lead to additional expense. I highly recommend that you match part numbers with the removed parts or have proven that they do actually work. The 89 C4 uses a single mass flywheel. The 1990 C4s and C2s use a Dual Mass flywheel and a resulting different set of part numbers.
Ciao,
Adrian
911C4

PS: Again, whilst it is possible to remove the engine and leave the transmission in the C4 I recommend you do not attempt this. It may well cost you far more time and money than what it is worth. There is no Porsche mechanic I know (deal with) who would even bother trying to leave the transmission fitted.

 

The hydraulic and the brake system are in one circuit. You need the Bosch hammer to de-lock the system and release or change the fluid.

 

Dear Chris,
I agree 100% with what you say and here is why. If you crack the ABS circuit or the Traction control circuit of a C4 you will need a Bosch Hammer to carry out the fluid refill and bleeding. If you just crack a brake circuit or the clutch circuit you will need only a pressure bleeder and the factory procedures to comeplete the job as long as you "Do Not" turn on the ignition. As long as the ABS and Traction Control solenoid remains closed then the brakes can be bled just using the pressure bleeder, new fluid and a bit of luck. It is critical however to ensure the factory procedures are followed. In a C4 when you pump the pedal you bleed off the pressure. You cannot bleed the brakes using the pedal with a C4 hydraulic system. Some people do try. The fluid does come out of course because it is still pressurised by the accumulator pressure. When the pressure is gone it is almost impossible to derpress the pedal.
However, I always highly recommend the use of the Bosch Hammer when bleeding the brakes of a C4. When the C4 was new and the seals were all perfect it worked. Many years down the track you get internal leaks. If you have internal leaks and no Bosch Hammer you cannot bleed the ABS and Traction control circuits.
If you remove the engine and transmission you will need to crack these hydraulic lines therefore you will need a Bosch Hammer.
Ciao,
Adrian
911C4

PS: My archives are full of private emails from people asking for help in this matter. Faults ranging from, I put my foot on the pedal and "I could not depress the pedal and needed the handbrake to stop", to people who say, "at 80mph one of the brakes applied itself". Normally the LH rear.