Ok, after searching here and elsewhere for about 2 hours and double checking the manual, I am completely stumped.

History: replaced engine with thrown rod and ventilated block with a new one. (new engine works great, by the way, this is the only thing keeping me from motoring). As a part of the process, drained trans fluid. During reassembly process, installed a new Luk clutch and pressure plate (part number 03-050) with throw out bearing and bearing support shaft. Used a Lucas Oil GL-4 gear oil on the transmission refill.

Symptoms: Gear lever selects all gears easily with clutch pedal in (or out) with engine off -feels just as it should. But with engine running, it is extremely hard to get into gear. Feels like with foot on floor, clutch is not completely disengaging. Can force it into gear, but feels very abusive, car lurches slightly. Feels like terrible syncro abuse to shift. Clutch pressure seems VERY light, but previous mini had a non dual-mass flywheel and clutch installed - so I am a terrible judge.

So after only a few shifts, decided to check clutch hydraulics. Plenty of fluid in reservoir. No weeping around slave (have seen that before on another Mini). Compressed slave and did a dozen or so cycles of 2-person clutch bleeding. Basically, no change. There is enough force developed by slave during bleeding with wooden spacer between slave and transmission to deflect the aluminum boss on transmission, so not a pressure issue.

Here are my thoughts and concerns:

Could not using the OEM or Redline fluid be somehow causing this?

What is the travel of the clutch slave supposed to be? Is it somehow just not pushing the clutch release lever far enough?

Could I have somehow mis-assembled something? This isn't my first R53 clutch job but I guess it is possible.

Ideas?

 

Edited: for misread of OP

 

Stoker, saw your original comment.

After I posted last night, I went out in desparation and played around with the clutch some more. If I pump the clutch pedal vigorously a few times first, I can achieve a normal gear engagement with the engine running. But when I go to make the next shift, it is hard again.

So crossing fingers, it really seems like a hydraulic system problem.

As you saw, I did try to bleed the system using a wooden wedge behind the clutch lever compressing the slave fully. But no air came out.

Any suggestions?

No apparent leaks looking at the parts.

 

I would say possibly vacuum bleed it , if pumping it makes it better you have air in it.

 

Don't forget, the brakes also need to be bled… I know, crazy right? they're on the same hydraulic system.. and yes +1 for the above post. if you have a compressor, harbor freight has a nifty little vacuum bleeder for $30.

Plus, the "Bleed Nipple" on the clutch cylinder (underneath the car) has to be very loose to get the brake fluid through it… careful when you tighten it, since its not very robust.. I swapped the nipple out for a metal one... but there's not much you can do about the plastic slave cylinder.

 

Picked up a vacuum bleeder and will try it out tonight.

 

Bled about 1/2 quart through the slave using a vacuum bleeder. Maybe got a little air out - not a lot. If I double pump the clutch the car is basically driveable.

What do I need to do to get the rest of whatever air is trapped in there out?

 

One trick...
Leave the clutch compressed overnight (or an Extented time period)...then bleed in the am...have never actually done it...but some have reported it worked.

 

Compress the clutch pedal (master), or the slave cylinder?

Thanks!

 

you also have to bleed the brake system, they share fluid with the clutch just bleeding the clutch wont do, if their is any air in the system at all it will effect the clutch pedal as well. one of the reasons Mini suggests you flush brake fluid at certain service intervals. Brake fluid absorbs water and darkens , when the fluid is dark its capable of rotting the lines from the inside out. I would flush the entire system starting at the furthest point away from the master as possible and working my way forward to the closest corner then the slave again. They have a full synthetic fluid that cannot absorb water, but the catch is it has to be used in a system clean of any old fluid, all seals exposed to old fluid will fail with the synthetic fluid dot 5 or 6 someone can correct that I cannot remember what type it is i only remember in the service the deuce and a halfs used it it was expensive and purple and couldnt mix with regular fluid because of this reason. The plus side was it cannot take water in and once sealed was amazing provided the air was out. New cars come with this alot of the time now just not sure about Mini, they like their services.

 

The clutch and brake systems share the same fluid reservoir but nothing else, no need to bleed brakes, just make sure the fluid is topped up.

My favorite trick to bleed the clutch slave is as follows:
unbolt the slave from the trans, hold slave cylinder so that the fluid line connection is the highest part, DO NOT open the bleeder valve. Let the piston slowly fully extend, then slowly compress the piston fully. Repeat this a few times, it will force any remaining air back thru the lines and out the top of the fluid reservoir.

Jason

P.S. watch the level in the reservoir as you do this, you might have to take a little fluid out so that it doesn't overflow when you compress the piston.