This is going back about 40 years but iirc when I took my car apart I found the vacuum reservoir tank to be full of brake fluid. But I can offer no solutions, sorry.
Good point. When I changed my booster and master I was told to check the vacuum tank and found at least a pint of fluid in it.
Really very easy to check. I just removed the check valve/hose fitting and used a length of wire as a dipstick. When it bottomed in the tank and came out dry I knew that wasnāt the problem.
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Yes & no. I used wire too as it is impossible to reach the bottom of the tank with a rigid dipstick. Wire came out showing signs of wetness. Took the tank out (lot of fun, donāt know how I got the bolts in when I installed it , but then I was 20 years younger then) and absolutely nothing drained out. Interior walls must be wet from lord only knows when.
To reiterate the circumstances, November I drove the Jag into the enclosed trailer, no red low fluid light, brakes OK. Had several straight days of temperatures in the 15 below zero range in January. I was concerned about the battery freezing if at low charge (trailer in in a storage facility, no electrical available), so I started the engine and let it run for about 10 or 15 minutes after reaching normal temperature. I do not know the brake fluid status at that time, the low fluid light would have been on because of the hand brake. 2 or 3 weeks ago I intended to take the car out of the trailer, but the brake pedal went right to the floor. Checked both of the brake fluid reservoirs and found they were essentially empty. No evidence of fluid on the floor of the trailer of anywhere else, but if the master or slave cylinder had leaked there would have been evidence on the splash pans under the cylinders.
I have a cockamamy theory, but I am not ready to embarrass myself quite yet.
Rod
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If the m/c pedal went to the floor then it or the booster were already partially dry. So just draining out your reservoirs from the top wouldnāt have done that. I have no clue if the brake seals get rock hard when the temp goes below zero. But if they do, extended idling with max manifold vacuum could suck the fluid out of the m/c and booster if the seal were leaking. Maybe some went to reservac and the rest went out the exhaust. Are all the rubber vacuum lines still in good shape and flexible? Assuming the brake fluid would attack the braided vacuum lines.
OK, rebuilt the slave/servo (found no fluid in the servo), no fluid in the vacuum reservoir, check valve OK, decided to replace the cup on the small reaction valve piston, which comes in the master cylinder overhaul kit, so decided to overhaul the master cylinder. Bad decision. I have struggled for several hours trying to get the main piston and associated parts out of the bore (yes, I removed the circlip). I assume the problem is one or both of the nylon bearings are seized in the bore. Any suggestions appreciated.
Rod
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Have you viewed this video. It has some hints on this problem:
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Take the master in hand and slam the flange squarely onto a steel plate. That should cause the bushing to shift. Keep at it until it drops out.
You might want to take a few minutes to review this video. He uses a large anchor and an eyebolt as an extractor:
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I have to admit defeat. The bearing block and piston are well and truly stuck. Thank you David and Mike for the U Tube suggestion. In a normal situation I believe the expanding wall anchor would have worked in extracting the piston. However in my situation the expanding fingers had nowhere enough grip. I modified the anchor such that the tapered area expanded tightly against the internal wall, and fashioned a threaded contraption to pull the piston. After several hours of mostly pulling the anchor out of the piston I succeeded in moving the bearing block to within about 1/16" of the mouth, wherein it stopped and refuses to move any further. I surmise that maybe the āOā ring gasket fitted in the groove of the bearing block disintegrated or somehow dislodged and is wedged between the block and interior wall.
Cheers,
Rod
Clamp the shaft in a vise with a hard wood block
Use a fly cutter to drill the block and then cut it in half, your making a round pad to grip the shaft
Clamp it tight in the vise
Rap the case off with a hammer and block placed on the ears close to center
Work it both directions
Soak it in brake fluid for lubrication
It needs to be solid to shock it with raps
Rod here is another method!
Put a plate on the ālittle piston ā endā¦
Put a bolt in the outlet
Put a fitting in the reservoir hole with a grease nipple
Attach grease gun and fill it with greaseā¦ā¦. Hydraulics are your friend and do it without danger
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Would heating up the cast iron body expand it enough to release it ?
I had the same problem, I ended up heating it up with a propane torch. It came apart, but the plastic gland was melted some. I got a new internal assembly for SNG Barratt. I also bought a housing with a stainless steel sleeve.
Iād say to just go ahead and replace it. Itās not a rare part.
Success, kinda. I tightly clamped the piston with a wood block, per Jimās suggestion. Initially same result as before, driving the piston shaft through the clamp block, not budging the piston out of the cylinder. At this point I decided it was time to take Mikeās advice, it was taking far to much of my time and was beginning to be an obsession, when new units are available at a not unreasonable price. But I was determined to get it apart to try and see what was causing the problem, even if I had to destroy it in the process. Reset the clamp, verified that there were gaps between the two halves of the block, tightened the vise with a cheater bar, got a very large ball peen hammer and beat the living snot out of it. This time the cylinder and piston separated just before the piston was about to come out of the clamp. Checked the parts and could find no obvious reason for the difficulty. I was wiping out the bore when something black fell out. Looks like it is a very small section of the seal that goes in the groove in the bearing block. Photo of parts below.
Now I am wondering if I should rebuild the cylinder?
Cheers,
Rod
Examine the bore for wear and corrosion. If youāre comfortable, rebuild. But given the grief itās already caused, it may be wiser to replace or resleeve.
There you go now get an old school brake cylinder hone and run it in and out , use brake fluid
Clean everything in brake fluid soak it over nite in a jar and get a kit
I use red rubber grease for assembly it stopās corrosion and lubricates
If the bore is the sealing surface, I would get it inspected by a very experienced brake man
I have had them sleeved in SS which is a lifetime repair (if done properly)
I could have sworn my MC was ok to just rekit, but when I showed it to my mate who is a lifetime brake expert, it took him 5 seconds to say sleeve it
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This entire brake issue has become a chore. I just want to get the car back on the road before winter sets in, so I just ordered a master cylinder from SNG.
Cheers,
Rod
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