Merak LHM Clutch bleed

I haven't bled a LHM clutch circuit before. Send Jason a pm he's just finished doing his Merak and everything went well.

http://www.ferrarichat.com/forum/143141255-post67.html

 

It was many years ago so excuse me if I am wrong but I recall working on a Khamsin that the clutch master cylinder reservoir was connected to the brake switch return line. Try pumping the brakes while the system is pressurized to see if LHM fluid gets to the clutch master.

Ivan

 

Ivan,

Is there a bleed screw on the slave? Maybe he needs to open that before anything will get to the master?

One those LHM system functional diagrams would be helpful or just the plumbing from the parts manual perhaps.

 

Here is a diagram, I sent you my email via PM and we can chat it through..

Thanks
Jason
Image Unavailable, Please Login

 

How were you able to get the clutch to bleed I have a 74 Merak and have the diagram however I'm getting fluid from the bleeder but no pressure is building at the clutch pedal. Thanks for the input.

 

If you want to PM me your number I can give you a ring, its probably easier than typing out a bunch of suggestions,

thanks

 

I have this issue following my Merak’s Winter hibernation. Did you every figure this out?

 

You'd figure there would be one single procedure how to bleed the LHM-boosted clutch or clutch slave, but I found none in the Owner's Manual or elsewhere.. so as a Community of enthusiast/owners, let's just take the time to share procedure and experiences here.

I welcome any and all comments..

I just rebuilt the clutch slave on my Khamsin, ran the engine, and found the pedal completely non-responsive afterwards. It obviously doesn't self-bleed. So, I took some clues from this thread and got it, so let me share what I did.

But first...

RE-BUILDING THE LHM CLUTCH SLAVE CYLINDER: Reference Parts Catalog Table 11.
- It takes four O-rings all together. Two on the clutch actuator piston, Parts 30 and 32 (note there are two styles of clutch slave shown), one is about 19mm and 2.the other 5mm ID, and 2.5mm thick, although all I could get were 3mm. I bought NAPA parts number 727-2613 and 727-2614 for less than $2.00. The other two O-rings are identical (Part 39) and seal the end caps at the tiny slider piston underneath. MIE sells a kit that includes a new boot with drain line (Part 35).
- The clutch slave dismounts fairly conventionally.
TIP - Start by indexing or measuring how much of the tip of the actuator arm (Part 24) protrudes from the adjustment nut (Part 21), so you can put it all back the same way afterwards. The disconnect the lo-pressure hose (12mm), the steel hi-pressure line (10mm), unbolt the slave and wiggle the heck out of it to get it off the actuator arm (Part 24), then take the last lo-pressure hose off (14mm).
TIP - Keep track of the copper washers at each lo-pressure banjo fitting. They are unique, and note the unusual copper spacer at the lower lo-pressure hose. You anneal these and re-use them if you have a plumber's propane torch. Hold each one in the bright blue part of the flame with a piece of hooked steel wire until they glow bright orange, then hang them on another wire to cool. Ready to re-use. (This annealing works for all intact copper washers e.g. oil drain plug, transmission drain plug, etc).
TIP - I added some length of silicone coated thermal sleeves over the lo-pressure hoses to shield against heat from the nearby exhaust pipe. I will probably fabricate a small heat shield for the whole slave cylinder assembly.

- Bring the slave to a bench and remove spring clip (Part 33) to pull the main cylinder (Part 31) out of its bore.This can be hard, so work the piston loose by pushing it inwards.. then work it out (I used the spring-clip removal pliers in their "outwards" mode to grab the inside bore of the piston and slowly, slowly, patiently wiggle it out).
- It is tricky to get the small retainer clips (Part 40) out of each end of the small lower slider piston bore. I suggest if there is no visible leaks at these end caps (Part 38, 39, 40, 43), do not replace those O-rings. They are non-moving parts. Only the slider piston (Part 37) moves within that area. If you must, then start by compressing or pushing the end caps (Part 38) inwards to work them loose from the grit that's collected. Work the caps back out by smacking the cast-iron slave housing squarely against an anvil or bench vice, using momentum to work that cap back. Push the cap back in, repeat until the end caps are moving better. Then you can press the caps (Part 38) inwards enough to get at and remove the spring clip (Part 40). Work the end cap out and free.
- Before you pull things out NOTE: Part 37 has a specific orientation and the ends have holes of different sizes. Verify which smaller vs larger hole faces towards the spring (Part 43) and which one doesn't. I actually got a little sidetracked, wasn't paying close attention.. My Part 37 seems to work fine with the larger-hole-end facing the spring (Part 43).
- To clean up the bores and edges a little I cut some scotchbrite pad material into a size that would snug into the bores of all cylinder spaces and clamped the other end of the scotchbrite into the chuck of my electric drill and ran it high speed to polish the bores.. Then rinse in clean mineral spirits or parts cleaner.
- I removed old O-rings, polished the pistons lightly, poured some LHM on them and installed the new O-rings.
- Soak the pistons and bores with a lot of LHM to ease the new O-rings into their bores.
- Reassembly is the reverse of the above.


BLEEDING THE LHM CLUTCH SLAVE:
- Using clues given in your posts above, I ran the engine, and worked the Brake and Clutch pedals. Sometimes alternately and sometimes at the same time, varying pedal travel and pedal pressure.. It took remarkably many strokes, but eventually I detected the clutch pedal starting to give some feel.. I did some pedal pushing with the engine off, using the accumulator pressure, and opened and let some LHM drip from the clutch slave bleed nipple, but it seems most progress was made simply by acting on the pedals.

Eventually the clutch pedal got back to its normal operating feel.

That's it.

Cheers.
- Art

 

Hi Art.

thank you for posting the procedure!! I will take a closer look at it when I return from vacation! I think it will be very helpful when the time comes!!

mike

 

@JasonMiller @3pedal360 @am117au ...

My clutch slave bleed hasn't been durable.. I end up pumping the pedal up after the Khamsin's been sitting overnight.. then it holds pressure for a day of driving.. But not overnight.

So I could still have a bad LHM O-ring seal in my clutch slave, or the bleed wasn't correct. I've used the bleed nipple some (I get no air or foam), and I'm working the brake and clutch pedals some.. But a fairly unorganized fashion.

Can you all offer any comment?
Cheers,
- Art

 

Now figure out how to convert the Bora!

 

I used the bleeder on the slave with wife pumping the clutch after system had been pressurized. If that does not work then you probably need to take another look at the o-rings.

Ivan

 

UPDATE: I opened the bleed nipple and expelled a few more ounces of LHM, still saw no foam or air. Then I did some more driving in it yesterday. Totally conventional methods. The clutch pedal now remains properly "hard" overnight. It seems to have finished bleeding itself.
- Art