Clutch

Assuming Boxer & TR same...

Fluid circuits for brakes and clutch are completely separate.

Why would the lack of fluid stop clutch engagement (if I'm reading correctly - "clutch starts fading and then goes away altogether") - no clue? Lack of fluid would affect dis-engagement.
For starters, I'd look for the leak. Hopefully your mechanic shed some light on the problem.

How we love them so!

 

I don't know at what fluid level the warning light should come "on", but, if you look at the 512TR or TR brake fluid/clutch fluid reservoir that supplies both systems, they (intelligently) put the port feeding the clutch master cylinder higher up than the ports feeding the brake master cylinder = clutch stops working first when fluid level goes down.

 

I had an issue on a drive where the car would work fine until the engine was nice and hot and the clutch wouldn't fully disengage and it was hard to get it into gear or shift gears. It was fine once it cooled down. So I believe the fluid was boiling. When I bled the fluid it came out black.

So maybe that's what happened, moist fluid boiled.

Sent from my Pixel 7 Pro using Tapatalk

 

The clutch slave cylinders have been known to leak. Simple bleeding would restore operation until fluid goes down again. Look for signs of leakage under the bell housing on rear cover of transaxle. Also there is a flex hose to the clutch at the left rear corner of power unit. Take a peek at that.

Might have a look at brake pads too. If very thin maybe fluid level down from that robbed fluid from clutch.

Look under dash at rear of clutch master for signs of fluid leakage.

I dont think level sensor comes out. Drain reservoir as well as possible. Stuff area under it with paper towels. It is held to master cylinder with 2 barbed nipples in 2 rubber grommets and will come off if pulled firmly straight up. Be careful not to get fluid on body. You can then test for freedom of movement of float and put an ohm meter on connections, roll reservoir over to test switch.

 

+1 to Brian's response. Another issue could be that the brake warning bulb system is not working (for a variety of possible reasons). I believe that whenever the starter motor is cranking, the brake warning light should also illuminate -- so make sure that that is actually happening during starter motor cranking.

 

Don't know, but you haven't sent me enough money to actually look at the painful 512TR schematics to figure it out and hurt my brain . I would guess that it's:
fluid low = float low = closed continuity
fluid normal = float high = open
but it could be reversed. I think it is safe to assume that, whatever the state is when the float is low, it will be the opposite state when the float is at the normal operating height.

 

So that's how it is now Steve? You got rid of your car and now you charge for your knowledge?
Ezored, you have to pull the pumpkin in order to change the slave bearing, the muffler stuff too.

 

Its worth it. He knows the electrics better than anyone.