reverse bleed

[smeegol]

I had a problem whereas my clutch pedal was halfway to the floor before any pressure.
After looking on the net and youtube , i saw a guy doing a reverse bleed on a bmw.
I gave it a go on my 75 cdti expecting it all to go **** up.
Removed the battery and compartment to get better access to the bleed nipple.
I attached the nipple to a tube at one end and a hand pump (oil can type) filled with brake fluid to the other bit of tube.
opened the bleed nipple and pumped away. The clutch was to the floor upon opening the nipple but to my surprise , after half fluid in the can had been pumped through the bleed nipple, and the nipple tightened... it was back to the top.
It was such a relief and a lot less messing about as i noticed it is so difficult to get to the reservoir behind the clutch pedal.
If this method has been mentioned on here before, it works perfectly.

[Heddy]

It seems that the reservoir would become the open bleed nipple, and any air would be released. Doesn't it just pump fluid all over the drivers floor though?
as a PS- does the M/C not have a one way valve?

[smeegol]

As the fluid cannot compress, it pushes the air upwards into the cylinder behind clutch and once all the air is pushed out (bubbles through the fluid ) there is just fluid left so you have to keep an eye on the level of the reservoir behind the clutch pedal.
close the bleed nipple and all is well.
A lot easier than having someone hold and pump the clutch pedal and try to pump the air through the system. the hand pump does the job of forcing the air in the opposite direction ,upwards to the reservoir behind the clutch pedal.
It really has worked for me first time. i could not get the car in gear and had to turn off engine to put in reverse before i did the fix.

[Heddy]

If it works, then why not, I'm guessing it bleeds the slave too?

[smeegol]

it bleeds the full system as it is forcing all the air upwards through to the master cylinder reservoir. as long as you keep and eye on the levels, as once the air has bubbled through the system and out of the reservoir, the level goes up as you pump more fluid in. at this point you just tighten the bleed nipple and the system is free of air.
watch these two...same principle
https://www.youtube.com/watch?v=wdf--suwqw0
https://www.youtube.com/watch?v=1P48s6Twk3w

[HarryM1BYT]

Originally Posted by Heddy

It seems that the reservoir would become the open bleed nipple, and any air would be released. Doesn't it just pump fluid all over the drivers floor though?
as a PS- does the M/C not have a one way valve?

The normal bleed method works perfectly, reverse bleeding is usually reserved for difficult systems where the normal method has been tried and failed. The merit in the method, is that air naturally wants to rise and reverse bleeding encourages that rise.

There is a valve in the piston, but the valve will not prevent you reverse bleeding the system.

Yes the fluid would spill out all over the drivers carpet, but it usually does that anyway

The design of the system means it almost bleeds itself anyway. There is a constant rise from clutch up to master, nowhere for air to really become stuck.

[FrenchMike]

And you can even avoid external help with this old trick:

800x600.jpg

Mike

[hogweed]

It's how my garage did mine this morning - he says it's just a lot easier, simple as that.

[Doc Evil]

Plenty of old towels on floor and below cylinder should save your carpets

Looks like a handy tip

Doc

[ceetdm]

My master cylinder still has the black condom inside which acts as a seal - so how would the air and fluid escape using this method?

I'm glad it works, I just don't understand how?

Tommy :-)