Clutch pump problem

[Laurent1602]

Hello,

Some days ago I refreshed the oil in the hydraulic system for the brakes and the clutch from a 3.0 CSi (1974). When I left the old oil out, I found there came out very little, but I didn't care to much.
When I wanted to bleed the clutch slave cylinder with the new oil, nothing came out! We set pressure on the system but it didn't help. We checked all the connections and pipes but they were fine. So we ended up with the head cylinder beeing the problem.
With the compressor on it we can blow air through the cylinder in the direction from the reservoir to the slave cylinder and not in the other direction, so far so good. Because I could blow air through the cylinder I thought it was fine again. We installed it back, but again, no oil came out...

I suspect the piston in the cylinder but I'm not sure how it could cause a problem and how to fix it. Does anyone can help me?

Thanks!

Laurent

P.S.: I know my English ain't perfect and I'm sorry for that, but I think it's good enough to understand?

 

[DaveG]

Maybe Flex lines swollen shut? How old are they?
DG

 

[Laurent1602]

All pipes and flexibles have been blown through so they should be good I assume. The problem is clearly with the master cylinder but I don't know really what the problem could be and how to fix it. The cylinder is replaced very recently so i can't be just weared neither...

 

[MMercury]

If I understand the problem, you attempted to bleed the clutch hydraulic system, but were unable to get any brake fluid out of the slave cylinder bleed screw. So you loosen the hoses, blew them out and ultimately replaced the head or "Master" cylinder. Now the clutch hydraulic system will not function?

 

[Laurent1602]

No, that's not exactly what happened ;-) I'll explain what happened from the beginning.

We replaced BOTH cylinders, bled them and everything was fine. However, after some days it turned out we used a wrong hydraulic fluid so I let the bad fluid out and replaced with the good one. When I tried to bleed with the new fluid, no fluid came out the bleed screw on the slave cylinder while bleeding with the pedal method as you describe, nor with pressure on the reservoir. After some investigating, it turned out that somewhere in the master cylinder the oil must be blocked. However, when we blow air through the cylinder, this passes fine (but this is with a much higher pressure).
We just tried again and we've set 2 bar on the hydraulic system and now finally some oil got through! However, as soon as this high pressure was gone, pumping with the pedal had no effect anymore... Again no oil gets through...

Could this be because there's still to much air in the system?

 

[DaveG]

What fluid did you put in it??????? You may have ruined ALL of the rubber parts, if you put anything but brake fluid in it!!!
The reservoir is shared with the brakes! If you put anything but brake fluid in there you REALLY need to flush the entire braking system! And even that may be too late!
DaveG

 

[Laurent1602]

It was ATF (Automatic Transmission Fluid). The shopkeeper was very sure it had to be this and I didn't know for sure... Now there's ATE DOT4 in it, because the ATF leaded to very poor braking. I don't really think ATF is that agressive to damage the rubber parts, or am I wrong?

The whole system is flushed already and the brakes are fine I think. Not able to test of course, the clutch doesn't work yet...

 

[DaveG]

WOW! I would regard every rubber component in the brake system as being bad until proven otherwise.
If this were my car, I would require the system to be completely cleaned and rebuilt.
If you flushed any of that fluid through the system, traces will still be in there.....And that is all it takes to swell up the rubber parts.

The proper way to deal with this would be to remove the Master Cyl and clean and replace all of the rubber seals. Remove all of the flex lines and flush the metal lines with plenty of Denatured Alcohol. Disassemble, clean and replace the O rings in the calipers. Then reassemble the system with new hoses, and bleed the system. All parts that came in contact with the contaminated fluid need to be cleaned with alcohol before they are re installed, and all rubber parts should be discarded.
Anything less is just "rolling the dice"

Sorry to be so harsh, but this really is a safety hazard!
DaveG

 

[DaveG]

Here's a fun thing to do....Take a wheel cylinder cup(seal) and put it in a glass with a little atf and let me know what happens after a couple days......

DaveG

Hint: It won't be anywhere close to it's original size......

 

[Laurent1602]

Well, actually the whole system was filled with ATF for a couple of days, but I don't think there's something wrong with the brakes. Everything is flushed now, and they seem to work. Needless to say, we'll be testing carefully and on safe roads with enough place for an emergency and without a lot of trafic.
There aren't leaks anywhere so far and the brake pedal feels solid.
Do you really think it is that dangerous to drive? Even not for a small test drive?

Also, isn't ATF used as a hydraulic fluid for power steering? Because that's what made me believe the shopkeeper. The bottle said "also for hydraulic systems". Of course now I know it's for power steering, but there are rubber seals in there too I guess?

 

[MMercury]

There aren't leaks anywhere so far and the brake pedal feels solid.
Do you really think it is that dangerous to drive? Even not for a small test drive?

Also, isn't ATF used as a hydraulic fluid for power steering? Because that's what made me believe the shopkeeper. The bottle said "also for hydraulic systems". Of course now I know it's for power steering, but there are rubber seals in there too I guess?

I am not an expert and I am absolutely certain that others are much better schooled on the subject.

Hydraulics generally refers to the use of a liquid to transfer or convey energy. It can be mineral oil and even water. http://en.wikipedia.org/wiki/Hydraulic_fluid This does not mean you would substitute vegetable oil or brandy in your brake system instead of brake fluid, or knowingly introduce water into your power steering system. Different hydraulic designs call for specific hydraulic fluids because of their specific properties, e.g., lubricity, volatility detergency, and biodegradability. Even if you were to overlook the fact that water is incompatible with the metal used in braking fixtures (rust), brake fluid, in particular, is designed to withstand the heat generated by friction, which can be substantial, and well above water's boiling point. By analogy, you would not likely substitute 50W motor oil or petrol for power steering fluid, anymore than you would run ATF or Kerosene in your engine - since the system was not designed to function with the former. It might work in a pinch, but for how long?

Confusion regarding fluid selection may have been because a few braking systems have been designed to function using mineral oil instead of the more common (and caustic) brake fluid. This includes some Rolls, Bentley and Jaguar models.

“The Jaguar XJ6, Vanden Plas, Majestic and Sovereign sedans manufactured from 1988 to 1992 and a few of the 1993 models had self-leveling hydraulic suspensions that required mineral oil. The 1988 and 1989 XJ6 also used it for the brake system. If your Rolls-Royce or Bentley is fitted with a green-capped hydraulic system reservoir, you have to use mineral oil. Please consult your owner handbook or reservoir instructions for details.” http://www.motorcarsltd.com/JLM9886.html

Returning to your major concern, you are by no means the first to mix hydraulic fluids.
Opinions vary on the subject., but the majority seem to side with cleaning, if not replacing, rubber bits. :sad:

:arrow:http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2133076

:arrow:http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2130605#Post2130722


Best I can offer. Please proceed with caution.

HTH

 

[Laurent1602]

In the first place, thanks for helping me all! I really didn't know ATF did that much damage to rubber parts :sad:

Well... You convinced me that this is pretty serious! I assume that my clutch problem also finds its cause here. There must have something broken or swollen in the master clutch cylinder.
I ordered all flexible hoses, a new master cylinder for the brakes (was pretty old already, so I'll renew it immediatly), repair kits for the clutch cylinders and repair kits for all calipers. That should do it when I clean all metal pipes and so on... Anything more I'd need?

I'll have to hurry, because I'd really like it to be ready August 19th :-o

 

[DaveG]

They have different types of rubber. Brake parts are not compatible with mineral oil based fluids like ATF. Brake fluid is a glycol-ester based fluid.
DaveG

 

[johanaxelson]

I can't speak for the brake side but on the hydraulic side you definitely don't want to mix the oils. As I understand it you can use a the newer green oil in old systems but the other way around? Very bad idea.
I learned the hard way from a garage that decided by themselves to change oils and poured the original oil into my system which is upgraded to a hydraulic booster after the 3.5 conversion.

Johan

 

[Honolulu]

Laurent: yes ATF can be used for brake fluid - in systems where it is designed and intended to. This does not include your coupe.

I think you should remove and clean the brake master and slave cylinders and lines connecting them.

Because the fluid flows back and forth only a short distance in the tubes, your calipers are probably clean unless you drained the entire system and refilled everything. I would disconnect the brake lines at or near the calipers and at the master cylinder, and blow them back towards the master to ensure there is no residue of ATF. Some cleaning solvent could be used to clean the pipes, then be sure to blow out all the solvent.

Your experience shows there was a problem after using ATF. Even though you may have cleaned it out since then, the only safe way to assess whether damage was done will be to disassemble and inspect the brake master and slave seal cups. Road testing risks your car, your person, anyone and anything you may hit if you are wrong.

 

[Laurent1602]

Thanks Honolulu!
Yes, the entire system was filled with ATF, so the calipers are probaly also in danger.
But we took the desicion and we'll revise the whole system and renew all rubbers. It's the only way to be safe, indeed.
The replacement parts are already coming our way.
It may indeed be a gamble to test and I don't like that, so we went for "safety first!"