996 brake fluid leak
Discussion
iaiin said:
Have noticed every month have to keep topping up brake fluid, so there must be leak somewhere? Is there a common place to start as all other problems i have had you guys on here normally are pretty accurate with your ideas? I suppose most faults are common to certain areas? cheers
Brake fluid leaks are rare so common faults are well, uncommon.There is good news and bad news.
The good news is brake fluid hydraulics are exposed or easy to expose and thus easy to examine for signs of a fluid leak.
The bad news is that unless you're adding a considerable amount of brake fluid every time you top up the fluid and you top up the fluid often the leak may be small. And brake fluid doesn't hang around so you'll have to use your hands and run them along the lines, feel around the fittings, the bleed screws, for any signs of fluid. Check your hand often for fluid wetness.
Remember brake fluid is harmful to paint so when you find what you suspect is brake fluid wash your hands with soap and water thoroughly to remove any brake fluid before you touch the car or anything else for that matter.
If you do not want to use your hands use a clean white paper towel and discard it and get a fresh one after the towel gets too dirty to be able to spot maybe just a drop/spot or two of brake fluid.
Remember to check the bleed screws -- inside and outside -- on each caliper and the flexible hoses. These can degrade and leak. Or someone doing a brake job can let the caliper hang by the hose which damages it or where it connect to the other line or caliper.
Check under the master cylinder too for any leaks where the lines connect to this.
If the car is a manual check the clutch lines and bleed screw and slave cylinder for any fluid leak sign.
You may have to enlist the help of a helper to press down on the brake pedal and hold it down as you search for a brake fluid leak. If the pedal goes down that's a good sign that there will be signs of a leak to find.
If the pedal stays put...be sure you are not mistaking pad/rotor wear and the resulting lowering of the brake fluid level in the reservoir as a leak.
Forgot to mention that if a caliper brake piston and its seal is leaking the fluid may be retained by the brake piston dust cover. No fluid may be yet visible so you have to get to the dust boots and feel each one for a squishy feel that could be a sign fluid is lurking inside the dust boot.
Edited by Rockster on Tuesday 26th February 23:59
Rockster said:
Brake fluid leaks are rare so common faults are well, uncommon.
There is good news and bad news.
The good news is brake fluid hydraulics are exposed or easy to expose and thus easy to examine for signs of a fluid leak.
The bad news is that unless you're adding a considerable amount of brake fluid every time you top up the fluid and you top up the fluid often the leak may be small. And brake fluid doesn't hang around so you'll have to use your hands and run them along the lines, feel around the fittings, the bleed screws, for any signs of fluid. Check your hand often for fluid wetness.
Remember brake fluid is harmful to paint so when you find what you suspect is brake fluid wash your hands with soap and water thoroughly to remove any brake fluid before you touch the car or anything else for that matter.
If you do not want to use your hands use a clean white paper towel and discard it and get a fresh one after the towel gets too dirty to be able to spot maybe just a drop/spot or two of brake fluid.
Remember to check the bleed screws -- inside and outside -- on each caliper and the flexible hoses. These can degrade and leak. Or someone doing a brake job can let the caliper hang by the hose which damages it or where it connect to the other line or caliper.
Check under the master cylinder too for any leaks where the lines connect to this.
If the car is a manual check the clutch lines and bleed screw and slave cylinder for any fluid leak sign.
You may have to enlist the help of a helper to press down on the brake pedal and hold it down as you search for a brake fluid leak. If the pedal goes down that's a good sign that there will be signs of a leak to find.
If the pedal stays put...be sure you are not mistaking pad/rotor wear and the resulting lowering of the brake fluid level in the reservoir as a leak.
Forgot to mention that if a caliper brake piston and its seal is leaking the fluid may be retained by the brake piston dust cover. No fluid may be yet visible so you have to get to the dust boots and feel each one for a squishy feel that could be a sign fluid is lurking inside the dust boot.
Many thanks, so its just a matter of a good look round & not somewhere to start first...There is good news and bad news.
The good news is brake fluid hydraulics are exposed or easy to expose and thus easy to examine for signs of a fluid leak.
The bad news is that unless you're adding a considerable amount of brake fluid every time you top up the fluid and you top up the fluid often the leak may be small. And brake fluid doesn't hang around so you'll have to use your hands and run them along the lines, feel around the fittings, the bleed screws, for any signs of fluid. Check your hand often for fluid wetness.
Remember brake fluid is harmful to paint so when you find what you suspect is brake fluid wash your hands with soap and water thoroughly to remove any brake fluid before you touch the car or anything else for that matter.
If you do not want to use your hands use a clean white paper towel and discard it and get a fresh one after the towel gets too dirty to be able to spot maybe just a drop/spot or two of brake fluid.
Remember to check the bleed screws -- inside and outside -- on each caliper and the flexible hoses. These can degrade and leak. Or someone doing a brake job can let the caliper hang by the hose which damages it or where it connect to the other line or caliper.
Check under the master cylinder too for any leaks where the lines connect to this.
If the car is a manual check the clutch lines and bleed screw and slave cylinder for any fluid leak sign.
You may have to enlist the help of a helper to press down on the brake pedal and hold it down as you search for a brake fluid leak. If the pedal goes down that's a good sign that there will be signs of a leak to find.
If the pedal stays put...be sure you are not mistaking pad/rotor wear and the resulting lowering of the brake fluid level in the reservoir as a leak.
Forgot to mention that if a caliper brake piston and its seal is leaking the fluid may be retained by the brake piston dust cover. No fluid may be yet visible so you have to get to the dust boots and feel each one for a squishy feel that could be a sign fluid is lurking inside the dust boot.
Edited by Rockster on Tuesday 26th February 23:59
At least it does not sound expensive fix..
iaiin said:
Many thanks, so its just a matter of a good look round & not somewhere to start first...
At least it does not sound expensive fix..
You can start looking wherever you want, but I'd probably start by getting the car on a lift and safely in the air and checking the brake system from under the car. Fluid will run down (naturally) so you have a better chance of spotting a leak starting at the very bottom of the car, the very lowest point of the car and looking up.At least it does not sound expensive fix..
Fittings are always suspect, then hoses, seals, bleed screws, with a cracked or holed steel line at the bottom of the list.
If the brakes have been worked on recently whatever work was done, wherever this work was done, like for instance a bleeding, I'd check the bleed screws for leaks. Maybe one didn't get tightened down all the way or is stripped or has some dirt in it.
Another problem is if the bleeding is done by pumping the brake pedal if the pedal is allowed to go too far down this puts the piston/seal into an area of the master cylinder it has never been in before and this can be dirty, corroded and this rough cylinder surface can degrade the master cylinder piston and its seal and this can result in a leak.
As I touched upon in an earlier post a caliper piston seal can leak but the dust boot can capture this fluid and you will not see any signs of a leak. All will be dry until the dust boot has collected too much fluid and it starts to seep or the boot cracks or splits and leaks fluid. To get at these dust boots you'll need to remove the wheels and maybe even the pads or even calipers so you want to eliminate every other possible leak source because checking the piston seals for leaks is getting into a bit of labor/time.
This is a long shot and not always conclusive and in fact subject to false positives but one possible clue a piston and piston seal is leaking is a pad or a pair of pads that have much more material on them than the others. Because of the leak the pads aren't be pressed as hard against the rotor and do not wear as much. Long shot but if you end up suspecting a piston seal this might save you having to remove 3 wheels/calipers before you get the 4th and leaking one.
Rockster said:
You can start looking wherever you want, but I'd probably start by getting the car on a lift and safely in the air and checking the brake system from under the car. Fluid will run down (naturally) so you have a better chance of spotting a leak starting at the very bottom of the car, the very lowest point of the car and looking up.
Fittings are always suspect, then hoses, seals, bleed screws, with a cracked or holed steel line at the bottom of the list.
If the brakes have been worked on recently whatever work was done, wherever this work was done, like for instance a bleeding, I'd check the bleed screws for leaks. Maybe one didn't get tightened down all the way or is stripped or has some dirt in it.
Another problem is if the bleeding is done by pumping the brake pedal if the pedal is allowed to go too far down this puts the piston/seal into an area of the master cylinder it has never been in before and this can be dirty, corroded and this rough cylinder surface can degrade the master cylinder piston and its seal and this can result in a leak.
As I touched upon in an earlier post a caliper piston seal can leak but the dust boot can capture this fluid and you will not see any signs of a leak. All will be dry until the dust boot has collected too much fluid and it starts to seep or the boot cracks or splits and leaks fluid. To get at these dust boots you'll need to remove the wheels and maybe even the pads or even calipers so you want to eliminate every other possible leak source because checking the piston seals for leaks is getting into a bit of labor/time.
This is a long shot and not always conclusive and in fact subject to false positives but one possible clue a piston and piston seal is leaking is a pad or a pair of pads that have much more material on them than the others. Because of the leak the pads aren't be pressed as hard against the rotor and do not wear as much. Long shot but if you end up suspecting a piston seal this might save you having to remove 3 wheels/calipers before you get the 4th and leaking one.
Rockster, many thanks for your help, i will book it in with garage as i dont have ramps or anything, at least it dont sound too expensive (hope ha ha ) Fittings are always suspect, then hoses, seals, bleed screws, with a cracked or holed steel line at the bottom of the list.
If the brakes have been worked on recently whatever work was done, wherever this work was done, like for instance a bleeding, I'd check the bleed screws for leaks. Maybe one didn't get tightened down all the way or is stripped or has some dirt in it.
Another problem is if the bleeding is done by pumping the brake pedal if the pedal is allowed to go too far down this puts the piston/seal into an area of the master cylinder it has never been in before and this can be dirty, corroded and this rough cylinder surface can degrade the master cylinder piston and its seal and this can result in a leak.
As I touched upon in an earlier post a caliper piston seal can leak but the dust boot can capture this fluid and you will not see any signs of a leak. All will be dry until the dust boot has collected too much fluid and it starts to seep or the boot cracks or splits and leaks fluid. To get at these dust boots you'll need to remove the wheels and maybe even the pads or even calipers so you want to eliminate every other possible leak source because checking the piston seals for leaks is getting into a bit of labor/time.
This is a long shot and not always conclusive and in fact subject to false positives but one possible clue a piston and piston seal is leaking is a pad or a pair of pads that have much more material on them than the others. Because of the leak the pads aren't be pressed as hard against the rotor and do not wear as much. Long shot but if you end up suspecting a piston seal this might save you having to remove 3 wheels/calipers before you get the 4th and leaking one.
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