Brake fluid leaking from master cylinder Reservoir to ABS reservoir. This causes to fluid to leak from the ABS Reservoir and lowers the Master Cylinder reservoir fluid level. How to solve this problem and the cost? 95 Honda Odyssey

the clutch fluid reservoir is at the clutch master cylinder or is an extension of the brake master cylinder
look for a hose from the clutch master cylinder to the brake master cylinder reservoir

For some reason these vehicles you need to bleed brakes several times, had same problem, so air hangs up in lines somewhere it apears. When you say brakes sticks, describe it better, locked up, or dragging on rotors?
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Check your brake master cylinder-your reservoir should be low if the master cylinder failed, and fluid could leak into the brake booster. Might be how the fluid winds up down below the brakes.

Also, could be from the clutch, if you have a manual with hydraulic clutch. Whichever it is will require replacing. Are any abs lines up under dash?

Hi, the likely cause is a leak that has used all the fluid in the reservoir and drawn air into the system. You will need to find the leak, repair it, and then bleed the whole system of air. Likely places for the leak are at the back of the master cylinder or at any of the 4 wheels. It is possible to draw air without a leak if your front brakes are extremely worn. If this is the case, replace the front brake pads and bleed only the front wheels. Please let me know if you have questions or need instructions, and thanks for using FixYa.

Yes, hydraulic--check again--fender side of brake master. Slave is usual cause of leak that eventually causes master reservoir to go dry and start drawing air. Check slave for leak. If leaking, replace slave and bleed system. Make sure to bench-bleed slave before installation by opening bleeder and pouring fluid into line port.

1. Raise and support the front end on jackstands.
2. Back off the flare nut on the fluid pipe to free the slave cylinder hose.
3. Pull off the hose-to-bracket retaining clip and pull the hose from the bracket. Cap the pipe to prevent fluid loss.
4. Unbolt and remove the slave cylinder.
5. Installation is the reverse of removal. Tighten the bolt to 12-17 ft. lbs. (16-23 Nm).

CLUTCH AND MASTER CYLINDER SHARE THE SAME RESERVOIR YOU CHECK LEVEL IN THE MASTER CYLINDER.ADD BRAKE FLUID TO THE MAX LINE DONT OVER FILL.IF MASTER CYLINDER RESERVOIR IS EMPTY.CHECK FOR FLUID LEAKS AT CLUTCH LINES AND CONNECTIONS AT CLUTCH RELEASE CYLINDER AND CHECK BRAKE LINES - CALIPERS - WHEEL CYLINDERS AND BRAKE BOOSTER.FIX LEAKS AND BLEED BRAKE AND CLUTCH SYSTEM.

Check the brake fluid first.is it low or no brake fluid at all.is the brake fluid got dried up or leaked out. Sounds like the power brake booster is bad, that is what the master cylinder is bolted too. There is a rubber hose that has a plastic valve in it were it snaps into the booster, Pull that rubber hose out of the booster and off of the engine, Now the end that you took off the engine. You should be able to **** through the line, but not be able to blow through it. If you can then replace the valve, It is a one way valve.
If that is all right then hook hose back up to the engine and start engine, You should hear a major vacuum leak at the valve end, put you finger over the valve and it should stop making noise and engine should smooth out. If it don't the rubber hose must be leaking or the tube on the engine were the hose hooks to is stoped up. Also check the master cylinder if power booster is replaced. If the brake light is coming and going check the brake light switch. check fig for the internal assembly parts:--

To check engine vacuum, connect a vacuum gauge to the supply hose that runs from the intake manifold to the booster. A low reading (below 16 inches) may indicate a hose leak or obstruction, a blockage in the exhaust system (plugged catalytic converter, crushed pipe, bad muffler, etc.), or a problem in the engine itself (manifold vacuum leak, bad valve, head gasket, etc.).
The condition of the diaphragm inside the booster is also important. If cracked, ruptured or leaking, it won't hold vacuum and can't provide much power assist. Leaks in the master cylinder can allow brake fluid to be siphoned into the booster, accelerating the demise of the diaphragm. So if there's brake fluid inside the vacuum hose, it's a good indication the master cylinder is leaking and needs to be rebuilt or replaced. Wetness around the back of the master cylinder would be another clue to this kind of problem.
To check the vacuum booster, pump the brake pedal with the engine off until you've bled off all the vacuum from the unit. Then hold the pedal down and start the engine. You should feel the pedal depress slightly as engine vacuum enters the booster and pulls on the diaphragm. No change? Then check the vacuum hose connection and engine vacuum. If okay, the problem is in the booster and the booster needs to be replaced.
Vacuum boosters also have an external one-way check valve at the hose inlet that closes when the engine is either shut off or stalls. This traps vacuum inside the booster so it can still provide one or two power assisted stops until the engine is restarted. The valve also helps maintain vacuum when intake vacuum is low (when the engine is under load or is running at wide open throttle). You can check the valve by removing it and trying to blow through it from both sides. It should pass air from the rear but not from the front.
Replacing a vacuum booster is a fairly straight forward job. All you have to do is disconnect it from the brake pedal on the inside and unbolt the master cylinder. The pushrod that runs from the booster into the back of the master cylinder must have the specified amount of play.
You will typically find the power brake booster mounted on the firewall attached to the master cylinder. The master cylinder is connected to the brake pedal.
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a Master rates about a 5 out of 10 with 10 being the hardest

you may find the hardest part is the actual bench bleeding of the master
and/or
the replacement of the reservoir

These are the instructions from my service manual, but I do not remove the fluid prior to service steps 2-6

1. Disconnect battery ground cable. Disconnect electrical connector from filler cap.
2. Remove fluid reservoir filler cap.
3. Raise and support vehicle.
4. Remove front wheels.
5. Remove dust cap and loosen bleed nipple. Connect a bleed tube to bleed nipple and into a suitable container.
6. Pump brake pedal until all fluid is expelled. Tighten bleed nipple.
7. Lower vehicle. Install brake fluid reservoir cap. Remove air cleaner and air cleaner outlet tube.
8. Disconnect central electrical box electrical connector.
9. Remove central electrical box retaining screw.
10. Remove central electrical box and relocate to air cleaner area.
11. Disconnect brake fluid feed tube. Disconnect brake lines.
12. On models with anti-lock brakes, disconnect brake lines from Hydraulic Control Unit.
13. On all models, remove brake booster vacuum hose.
14. Extract master cylinder from vehicle.
15. On models with manual transaxles, remove clutch hose from brake/clutch reservoir.
16. On all models, remove master cylinder nuts and remove master cylinder.

To install, reverse removal procedure. Bleed brake system.

If the brake warning light comes on when you apply the brakes, or is on continuously, it means that hydraulic pressure has been lost in one side of the brake system or that the fluid level in the master cylinder is dangerously low (due to a leak somewhere in the brake system). In either case, the fluid level in the master cylinder should be checked. Adding brake fluid to the master cylinder reservoir may temporarily solve the problem. But if there's a leak, the new fluid will soon be lost and the warning light will come back on.
Brake fluid leaks are serious because they may cause the brakes to fail! So avoid driving the vehicle until the system can be inspected to determine what's wrong. Leaks can occur in brake hoses, brake lines, disc brake calipers, drum brake wheel cylinders or the master cylinder itself. Wet spots at hose or line connections would indicate a leak that needs to be fixed.
Leaking brake fluid can also contaminate the brake linings, causing them to slip or grab. The uneven braking action that results may cause the vehicle to veer to one side when the brakes are applied. Brake shoes or pads that have been contaminated with brake fluid cannot be dried out and must be replaced.

hi from uk if you are saying that the brake master cylinder reservoir fluid is falling in level? and that there is signes that fluid is leaking from the ABS hydraulic master cylinder ie fluid is leaking from the arpeture where the electrics wiring loom enters then there is probably one of the piston/valve seals leaking within abs assy ? or is leak from somewhere else? not had this problem before with fluid passing from abs assy resulting in reservoir losing fluid in this way?