Hydraulic clutch problems

I need some advice: first some background.1986 CJ-7. I converted my
mechanical clutch to a hydraulic clutch about four years ago.



Everything worked great until last week when all off a sudden, I have no
clutch pedal. The pedal went all the way to the floor and the clutch does
not depress. I looked at the master cylinder and all the fluid was black,
and it was seeping out of the bore down both sides of my firewall (engine
and passenger compartment). Ok, so a bad master cylinder (I thought).



I buy a new one, bleed it, and it works fine for about a day. Then the same
problem. No clutch pedal, but no leaks. I figure it must be air in the
line. Bleed it again and everything is rosy for about a week. Last night I
come to a stop sign.NO CLUTCH, WTF!!!!



I bought a brand new master cylinder (not rebuilt) so I'm hesitant to blame
it. I don't see any leaks in the hydraulic line. Is the system sucking up
air somehow? If it sucked in air, wouldn't the reverse be true i.e. it
would shoot out hydraulic fluid?



The slave seems to be fine. No leaks.

Jo Baggs wrote:
> I need some advice: first some background.1986 CJ-7. I converted my
> mechanical clutch to a hydraulic clutch about four years ago.
>
> Everything worked great until last week when all off a sudden, I have
> no clutch pedal. The pedal went all the way to the floor and the
> clutch does not depress. I looked at the master cylinder and all the
> fluid was black, and it was seeping out of the bore down both sides
> of my firewall (engine and passenger compartment). Ok, so a bad
> master cylinder (I thought).
> I buy a new one, bleed it, and it works fine for about a day. Then
> the same problem. No clutch pedal, but no leaks. I figure it must
> be air in the line. Bleed it again and everything is rosy for about
> a week. Last night I come to a stop sign.NO CLUTCH, WTF!!!!
>
> I bought a brand new master cylinder (not rebuilt) so I'm hesitant to
> blame it. I don't see any leaks in the hydraulic line. Is the
> system sucking up air somehow? If it sucked in air, wouldn't the
> reverse be true i.e. it would shoot out hydraulic fluid?
>
> The slave seems to be fine. No leaks.

Had a tractor once that did somethign similar.

There can be leaks around the piston, that won't show outside
and will give you the same result.

As for testing, the only test I have only seen two tests.
a pressure gauge between slave and master cyl and ye-olde
mechanics stethoscope.

Some times pumping or jumping on it will get enough pressure
built up.

That's my best guess.

--
DougW

"DougW" > wrote in message
...
> Jo Baggs wrote:
>> I need some advice: first some background.1986 CJ-7. I converted my
>> mechanical clutch to a hydraulic clutch about four years ago.
>>
>> Everything worked great until last week when all off a sudden, I have
>> no clutch pedal. The pedal went all the way to the floor and the
>> clutch does not depress. I looked at the master cylinder and all the
>> fluid was black, and it was seeping out of the bore down both sides
>> of my firewall (engine and passenger compartment). Ok, so a bad
>> master cylinder (I thought).
>> I buy a new one, bleed it, and it works fine for about a day. Then
>> the same problem. No clutch pedal, but no leaks. I figure it must
>> be air in the line. Bleed it again and everything is rosy for about
>> a week. Last night I come to a stop sign.NO CLUTCH, WTF!!!!
>>
>> I bought a brand new master cylinder (not rebuilt) so I'm hesitant to
>> blame it. I don't see any leaks in the hydraulic line. Is the
>> system sucking up air somehow? If it sucked in air, wouldn't the
>> reverse be true i.e. it would shoot out hydraulic fluid?
>>
>> The slave seems to be fine. No leaks.
>
> Had a tractor once that did somethign similar.
>
> There can be leaks around the piston, that won't show outside
> and will give you the same result.
>
> As for testing, the only test I have only seen two tests.
> a pressure gauge between slave and master cyl and ye-olde
> mechanics stethoscope.
>
> Some times pumping or jumping on it will get enough pressure
> built up.
>
> That's my best guess.
>
> --
> DougW

After I bleed it, it works fine. Then suddenly, NO MORE CLUTCH. It feels
like it's not pressing on anything. Then I bleed it and it works. No fluid
loss. I'm baffled. Is it the Master Cylinder or the Slave?

Jo Baggs wrote:

>
> "DougW" > wrote in message
> ...
>> Jo Baggs wrote:
>>> I need some advice: first some background.1986 CJ-7. I converted my
>>> mechanical clutch to a hydraulic clutch about four years ago.
>>>
>>> Everything worked great until last week when all off a sudden, I have
>>> no clutch pedal. The pedal went all the way to the floor and the
>>> clutch does not depress. I looked at the master cylinder and all the
>>> fluid was black, and it was seeping out of the bore down both sides
>>> of my firewall (engine and passenger compartment). Ok, so a bad
>>> master cylinder (I thought).
>>> I buy a new one, bleed it, and it works fine for about a day. Then
>>> the same problem. No clutch pedal, but no leaks. I figure it must
>>> be air in the line. Bleed it again and everything is rosy for about
>>> a week. Last night I come to a stop sign.NO CLUTCH, WTF!!!!
>>>
>>> I bought a brand new master cylinder (not rebuilt) so I'm hesitant to
>>> blame it. I don't see any leaks in the hydraulic line. Is the
>>> system sucking up air somehow? If it sucked in air, wouldn't the
>>> reverse be true i.e. it would shoot out hydraulic fluid?
>>>
>>> The slave seems to be fine. No leaks.
>>
>> Had a tractor once that did somethign similar.
>>
>> There can be leaks around the piston, that won't show outside
>> and will give you the same result.
>>
>> As for testing, the only test I have only seen two tests.
>> a pressure gauge between slave and master cyl and ye-olde
>> mechanics stethoscope.
>>
>> Some times pumping or jumping on it will get enough pressure
>> built up.
>>
>> That's my best guess.
>>
>> --
>> DougW
>
> After I bleed it, it works fine. Then suddenly, NO MORE CLUTCH. It feels
> like it's not pressing on anything. Then I bleed it and it works. No
> fluid
> loss. I'm baffled. Is it the Master Cylinder or the Slave?

Two thoughts here. Generally, the master cylinder has just a
simple "flapper" valve that allows the return fluid into the chamber at a
controlled rate - if the line has no low spots, most will bleed on their
own (over a longish period) unlike a brake master which maintains a slight
positive pressure. The black crap in the fluid is likely rubber FROM
SOMEWHERE and it will hold that valve open so that the pedal goes to the
floor with no effect. If the fluid is black, then it's likely that there is
a pile of black crud built up in the cylinders and that same crud will also
get between the cups and the cylinder walls causing a leak. At a minimum,
you need to flush the system really well but chances are you need new
cylinder cups as well. Chances are that the cups were the cause of the
crud in the first place - they wore and shed.

One other cause of the contamination is the rubber in the hose section(s) of
the line. Replace those if you flush.

Long and short of it is that once you get this kind of contamination in the
fluid you're going to have to rebuild or replace both the master and the
slave - that's been the usual case with about any hydraulic system I've
ever worked on, not just clutch and brakes.

--
Will Honea

The black stuff strongly implies the fluid got contaminated or it is the
wrong fluid for the system. When this happen, the 'rubber' looking
parts like piston cups and O-rings turn to black goo.

The only fix I know for the black goo issue is to change all the parts
out that have any 'rubber' type parts in them.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '09. Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com

Jo Baggs wrote:
> I need some advice: first some background.1986 CJ-7. I converted my
> mechanical clutch to a hydraulic clutch about four years ago.
>
>
>
> Everything worked great until last week when all off a sudden, I have no
> clutch pedal. The pedal went all the way to the floor and the clutch does
> not depress. I looked at the master cylinder and all the fluid was black,
> and it was seeping out of the bore down both sides of my firewall (engine
> and passenger compartment). Ok, so a bad master cylinder (I thought).
>
>
>
> I buy a new one, bleed it, and it works fine for about a day. Then the same
> problem. No clutch pedal, but no leaks. I figure it must be air in the
> line. Bleed it again and everything is rosy for about a week. Last night I
> come to a stop sign.NO CLUTCH, WTF!!!!
>
>
>
> I bought a brand new master cylinder (not rebuilt) so I'm hesitant to blame
> it. I don't see any leaks in the hydraulic line. Is the system sucking up
> air somehow? If it sucked in air, wouldn't the reverse be true i.e. it
> would shoot out hydraulic fluid?
>
>
>
> The slave seems to be fine. No leaks.
>
>

"Mike Romain" > wrote in message
ng.com...
> The black stuff strongly implies the fluid got contaminated or it is the
> wrong fluid for the system. When this happen, the 'rubber' looking
> parts like piston cups and O-rings turn to black goo.
>
> The only fix I know for the black goo issue is to change all the parts
> out that have any 'rubber' type parts in them.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 'New' frame in the works for '09. Some Canadian Bush Trip and Build
> Photos: http://mikeromainjeeptrips.shutterfly.com
>
> Jo Baggs wrote:
>> I need some advice: first some background.1986 CJ-7. I converted my
>> mechanical clutch to a hydraulic clutch about four years ago.
>>
>>
>>
>> Everything worked great until last week when all off a sudden, I have no
>> clutch pedal. The pedal went all the way to the floor and the clutch
>> does
>> not depress. I looked at the master cylinder and all the fluid was
>> black,
>> and it was seeping out of the bore down both sides of my firewall
>> (engine
>> and passenger compartment). Ok, so a bad master cylinder (I thought).
>>
>>
>>
>> I buy a new one, bleed it, and it works fine for about a day. Then the
>> same
>> problem. No clutch pedal, but no leaks. I figure it must be air in the
>> line. Bleed it again and everything is rosy for about a week. Last
>> night I
>> come to a stop sign.NO CLUTCH, WTF!!!!
>>
>>
>>
>> I bought a brand new master cylinder (not rebuilt) so I'm hesitant to
>> blame
>> it. I don't see any leaks in the hydraulic line. Is the system sucking
>> up
>> air somehow? If it sucked in air, wouldn't the reverse be true i.e. it
>> would shoot out hydraulic fluid?
>>
>>
>>
>> The slave seems to be fine. No leaks.

Thanks Doug, Will, and Mike.
The fluid is no longer black as I flushed out the old fluid. The master is
brand new. Does the slave have any rubber parts? What would go wrong with
the slave (bad seals). Should I return the Master to the Brake shop for
possible defect?
Thanks

Jo Baggs wrote:
> "Mike Romain" > wrote in message
> ng.com...
>> The black stuff strongly implies the fluid got contaminated or it is the
>> wrong fluid for the system. When this happen, the 'rubber' looking
>> parts like piston cups and O-rings turn to black goo.
>>
>> The only fix I know for the black goo issue is to change all the parts
>> out that have any 'rubber' type parts in them.
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 'New' frame in the works for '09. Some Canadian Bush Trip and Build
>> Photos: http://mikeromainjeeptrips.shutterfly.com
>>
>> Jo Baggs wrote:
>>> I need some advice: first some background.1986 CJ-7. I converted my
>>> mechanical clutch to a hydraulic clutch about four years ago.
>>>
>>>
>>>
>>> Everything worked great until last week when all off a sudden, I have no
>>> clutch pedal. The pedal went all the way to the floor and the clutch
>>> does
>>> not depress. I looked at the master cylinder and all the fluid was
>>> black,
>>> and it was seeping out of the bore down both sides of my firewall
>>> (engine
>>> and passenger compartment). Ok, so a bad master cylinder (I thought).
>>>
>>>
>>>
>>> I buy a new one, bleed it, and it works fine for about a day. Then the
>>> same
>>> problem. No clutch pedal, but no leaks. I figure it must be air in the
>>> line. Bleed it again and everything is rosy for about a week. Last
>>> night I
>>> come to a stop sign.NO CLUTCH, WTF!!!!
>>>
>>>
>>>
>>> I bought a brand new master cylinder (not rebuilt) so I'm hesitant to
>>> blame
>>> it. I don't see any leaks in the hydraulic line. Is the system sucking
>>> up
>>> air somehow? If it sucked in air, wouldn't the reverse be true i.e. it
>>> would shoot out hydraulic fluid?
>>>
>>>
>>>
>>> The slave seems to be fine. No leaks.
>
> Thanks Doug, Will, and Mike.
> The fluid is no longer black as I flushed out the old fluid. The master is
> brand new. Does the slave have any rubber parts? What would go wrong with
> the slave (bad seals). Should I return the Master to the Brake shop for
> possible defect?
> Thanks
>

Yes, the junk could have come from both, would have even if the fluid
was wrong or something got in there.

Because the problem is still ongoing, I would change the bottom out also.

I just changed rusty brake lines and did all the calipers and cylinders
along with the master too. The fluid was rusty even.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '09. Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com