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Endless bubbles when trying to bleed clutch

111 views 11 replies 3 participants last post by  yass98i  
#1 ·
When driving in highway suddenly the gears became too hard to shift as if the clutch was not even pushed. When engine stopped all gears engage.

So the problem is from the clutch actioning

I have hydraulic clutch. I inspected the slave cylinder (from a square hole) and the master cylinder and no leaks were found so I thought let’s bleed the circuit.

I have a vacuum syringe so I hook it up on the bleeding nipple and suck the hydraulic fluid. At the beginning the liquid was dark and then became like fluid brakes, but through all the process I had endless bubbles coming I was expecting that at some point only liquid would flow. I did the process several times and extracted approximately 500mL of brake fluid. I was always topping up the reservoir so no air was coming from there.

Do you think I should continue doing like this till no bubbles come or is there a leak somewhere hence the air gets into the circuit and goes to the vacuum pump.

Thanks for your help
 
#4 ·
At the beginning I thought it was linked but after inspecting the master cylinder and slave cylinder I see no leak and even the hydraulic line seems intact. So that other leak I don’t really know where is it. I changed the gearbox oil back then but the oil was on level. Really curious case, but can not know where to look when under the car.
 
#6 ·
Some updates sadly not positive.
I tried to bleed by 3 different methods. I think the system is correctly bled but maybe slave or master cylinder is faulty.
I tried with the clutch pumping method and putting a hose on a bottle and looping the hose around exhaust so when the clutch is going back air does not go inside as the loop and the gravity keeps fluid always at the nipple exist. Clutch feels good. But did not solve problem so I thought about doing the brake caliper method and same result.

the clutch pedal feels like normal so I think it’s correctly bled but what I do not understand is how the master or slave cylinder could stop working without leak.
the leak in my previous posts are not related with the clutch system as the leak does not come from there.

I will order the master cylinder and try again as it’s the simplest and cheapest to replace. But if it’s not the master cylinder then I need to take out gearbox to change the slave 🥲😕
 
#10 ·
Update:


I recorded the clutch from the bleeding opening and we can see that the clutch is working but don’t know if it needs to displace more or not. Is that enough? Do you think I need to bleed the system more ? I received the Master cylinder, do you think I should replace it ?
Thank you
 
#11 ·
I’m going to take down the gearbox this weekend. After some research about the Self Adjusting Clutch (SAC) I think that maybe it overadjusted and therefore the travel of the springs that detach the pressure plate from the disk and flywheel has reduced and thus the clutch push is not enough to make them separate.

My SLK is 200kkm, do you think I should change also the clutch anyway? Or just resetting the auto adjuster is enough? I don’t experience any slipping from the clutch so I think it can do more.
I also ordered all the gearbox seals to end the gearbox leaks.
 
#12 ·
Image

Update:

I took the gearbox out, it was pretty easy.
Indeed SAC was all the way to the other end just I réajusted it.

Machine Vehicle brake Locking hubs Rotor Nickel

Clutch Synthetic rubber
 
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