Brake fluid leakage- help required!

[santosh.s]

Last week, it was time for the 5th service of my car (which is a Maruti baleno). The guy called me to inform that there are symptoms of brake fluid leakage from brake cylinder in one of the rear wheels (which are drum-type). He insisted on changing the cylinder itself, but I was not convinced since I haven't noticed any drop in fluid level over past 3 years. It was never replaced all these years, and it still remained above the max level. He tried to scare me (I thought so, but could be genuine as well) reminding me that braking is such an important thing which should not be taken chance with. But since the cost was not negligible (Rs. 2K), I didn't trust him blindly. He also told me that the fluid should have been replaced during the last service itself (2 years/20K Km) as per the schedule, blaming the service center where it was done. I asked him to change the fluid, but leave the cylinder as is. He told me that after the fluid replacement, the leakage will be more for sure (100% saar!). But I told him that I will keep watching the level on a daily basis, and in case I see it dropping I would get back. He agreed on that, though reluctantly. I also checked that brake warning light and the float sensor is working properly. I do check the fluid level and the light every time I use the car. It has been over 5 days and guess what- there is absolutely no drop in the fluid level that I could notice! So, I have following questions in mind-

1. They showed me the leakage in order to convince me, the moment they opened a rubber cap on the brake cylinder, it was all wet inside and also a couple of drops spilled around. Whereas the cylinder on the other side was quite dry. But given that the whole system contains only half a liter of fluid, in spite of that level hardly dropped over good 3 years period, and I had never experienced any problems with braking, I dared not to get it fixed thinking it must be a very minor leak, if at all. I also heard one mechanic telling the other something like this (though I couldn't understand their language well)- It is just some "bleeding", thats it!. I wanted to know what others have to say. Does it look like a serious problem?

2. Does Maruti cover replacement of brake cylinders under warranty (extended-warranty for that matter)? I referred to the extended warranty booklet, but it seemed confusing, a lot left to interpretation! It says- cylinder is covered, but "regular wear" components inside are not covered. It also mentions that such parts, if replaced under scheduled servicing, are not covered! Please help me understand them better!!

[Atlblkz06]

Jack up the car, take out the wheel and see for yourself
If you see a black sticky mess there, you may have a leak.

[santosh.s]

I am usually watchful about any stains in the parking area, never seen anything suspicious.

[SirAlec]

If braking is fine you need not worry!

But on second thought, do the following.
Put the car on ramp or jackup. open the rear drum. start the engine and pump the brakes few times. Watch any sign of leakage or brake oil spray at these spot. Its very easy to figure.

[santosh.s]

When the mechanic showed it to me, there weren't any visible signs of leakage on the cylinder or surrounding area. Traces of oil were seen only when one of the rubber caps (pointed by red arrows in the image you posted) was removed.

Jacking up and removing the wheel is fine, but I don't think I would be comfortable removing the drum altogether (moreover, I don't have required tools)! If you think just keeping a watch on fluid level (say daily for a month or so) would be safe enough, then I would avoid the rest.

[santosh.s]

Originally Posted by SirAlec

If braking is fine you need not worry!

Sigh!! that gives me reassurance- that I am not really taking a chance
Braking is absolutely fine, as it has been always.

[sgiitk]

If there is any trace of fluid unless due to the initial installation (very unlikely) you have a problem brewing. If as you say you have not used up any fluid then you may be Ok but keep a cautious eye. However, brake fluid in the reservoir does tend to get lower esp. as disc pads wear.

Brakes are vital to safety and I will tend to go with the advisor and change the cylinder. If you are at two years (which is what I think you are) then brake fluid should be changed in any case.

[gd1418]

Santhosh,

How many Kms the Baleno has run and how old is your car?

[santosh.s]

The car is a little over 3 years old, but mileage is much on the lower side in spite of being regularly used (almost daily). If I compare actual mileage against maximum time period and mileage allowed before each service in the maintenance schedule, then it has been roughly half the specified figures. As of now it has clocked just about 16-17K Km. Regarding usual wear and tear, I consider myself a sane driver (rather insane driving is impossible in Bangalore city!). Heavy braking is limited to rare occasions of high speed driving on highways.

@sgiitk, brake fluid has been already replaced during recent 3-years service. As I mentioned earlier, it was supposed to be done in the previous (2 years) service itself, but those guys missed it. I am aware of expected drop in level due to wear, all I can say is that it was negligible so far, in the sense it never came below the MAX mark. It is possible that they might have topped it up in the previous service. But then I have been watching all fluid levels once in a while, so anything considerably below MAX level would have gotten my immediate attention. Therefore possibility of topping up last time is very unlikely, and it must have been a small quantity if at all.

[ak-47]

Originally Posted by santosh.s

........
But I told him that I will keep watching the level on a daily basis, and in case I see it dropping I would get back. He agreed on that, though reluctantly. I also checked that brake warning light and the float sensor is working properly. I do check the fluid level and the light every time I use the car. It has been over 5 days and guess what- there is absolutely no drop in the fluid level that I could notice! ...........

I had a similar experience of brake fluid leak (please read my earlier post : http://www.team-bhp.com/forum/1091939-post57.html (Tata safari rear brake release Valve(non ABS), disaster by design?) ); But in my case, even the indicator had failed at the same time, along with the leak !.

So, checking the fluid level and the indicator regularly, is a must under the circumstances. I would still recommend a second opinion - i.e. take the car to another reputed garage and get the cylinder inspected.

[sgiitk]

Rubber brake parts fail more on age than driving. Three years is a bit early for a brake overhaul (more like 5-6 years) but one never knows.

If you keep a daily watch (I hope you actually follow your pious intentions) and get the cylinder attended to at the first sign of trouble you should be Ok. Please keep (say) 100-250ml of brake fluid in the car for an emergency.

However, I will be inclined to take care of cylinder at the first convenient opportunity.

[santosh.s]

Thank you guys for all the gyan!

@ak-47, I completely read the thread you mentioned (I had to)

Also, went through the braking system chapter of baleno's service manual. I felt greatly relieved when I came to know that because of primary/secondary arrangement of circuits, entire braking system can not fail at once, even if one circuit gets completely drained out due to a leakage. Each hydraulic circuit takes care of two wheels, one front and one rear which are diagonally opposite. It is true that leakage in any one circuit will eventually drain out fluid from reservoir. But before the other circuit fails, I would expect to get ample indications to notice it and time to get it fixed. Any one of the following can warn you ahead of potential danger-
- Excessive brake pedal movement.
- May be lesser braking effectiveness as braking is applied to only two wheels.
- Empty fluid reservoir. If you have a habit of checking engine compartment once in a while, you should catch it in advance (unless leakage is abrupt).
- Brake failure warning light.
- Stains around wheels, parking area.

I believe when you unfortunately experienced a complete failure, it must have failed partially first and above symptoms must have gone unnoticed.

Also, I strongly feel (based on my understanding) that even when one of the circuits as well as the reservoir is entirely drained out, the other circuit should be effective for quite some time.... until you wait for another leakage to develop in it OR brake pads wear out enough to eventually let air bubbles creep into it, causing "spongy" pedal first followed by gradual failure. Am I getting it right??

PS: don't get me wrong, I am not trying to justify further delay in my repair, I will get it done soon anyway. Arguments above are just to understand how exactly braking system works, and more importantly what to look for in case of problems!

[ak-47]

Originally Posted by santosh.s

................ It is true that leakage in any one circuit will eventually drain out fluid from reservoir. But before the other circuit fails, I would expect to get ample indications to notice it and time to get it fixed. Any one of the following can warn you ahead of potential danger-
- Excessive brake pedal movement.
- May be lesser braking effectiveness as braking is applied to only two wheels.
- Empty fluid reservoir. If you have a habit of checking engine compartment once in a while, you should catch it in advance (unless leakage is abrupt).
- Brake failure warning light.
- Stains around wheels, parking area.

I believe when you unfortunately experienced a complete failure, it must have failed partially first and above symptoms must have gone unnoticed.

@santosh.s, I agree. You would see some/all of the symptoms. Because of the failed indicator in my case, I had no clue until it happened - and, yes, I must have overlooked the subtle changes.

Originally Posted by santosh.s

Also, I strongly feel (based on my understanding) that even when one of the circuits as well as the reservoir is entirely drained out, the other circuit should be effective for quite some time.... until you wait for another leakage to develop in it OR brake pads wear out enough to eventually let air bubbles creep into it, causing "spongy" pedal first followed by gradual failure. Am I getting it right??

From what I know/understand, if the master cylinder is entirely drained out - I don't think either of the circuits would be effective - even if some fluid is present in the circuit. Not even for a short time. At least some fluid is required to be displaced in the master cylinder so as to create the pressure on the circuits.

BTW, since your brake-fluid indicator is fine, why not just keep some spare brake fluid in the car. You can top up at the first instance of the low-level indication, and that should give you enough time to reach the nearest garage - if and when you face a brake-leak situation.

[anupmathur]

Originally Posted by santosh.s

Also, I strongly feel (based on my understanding) that even when one of the circuits as well as the reservoir is entirely drained out, the other circuit should be effective for quite some time.... until you wait for another leakage to develop in it OR brake pads wear out enough to eventually let air bubbles creep into it, causing "spongy" pedal first followed by gradual failure. Am I getting it right??

Dual circuit brakes have a dual/tandem master cylinder and a dual-chamber reservoir.
Leakage in one wheel's piping can drain half of the system, but the other half stays fully functional.

[santosh.s]

Originally Posted by ak-47

From what I know/understand, if the master cylinder is entirely drained out - I don't think either of the circuits would be effective - even if some fluid is present in the circuit.

Master cylinder has two isolated compartments, if both of them are drained out, then I agree that none of the brakes will work. By "circuit" I meant inclusive of master cylinder, each of the two portions of the master cylinder being included in respective circuit. If everything is perfect except for leakage in one circuit, like a wheel cylinder leakage, then the other circuit should not get drained. Otherwise there is no point in primary-secondary tandem design, it will defeat the purpose. However, if the piston that separates primary and secondary compartments is also leaky, then the two would no longer remain isolated and both will be drained out eventually. But my point wast that it can not happen just because one wheel-cylinder had a leak.

That said, the piston separating primary and secondary master cylinder compartments seems to be almost redundant under normal condition. It has a role to play only when one of the circuits fails! As this would be very rare and something that nobody would like to test, it may be very difficult to know if that piston is free of leaks.

Originally Posted by anupmathur

Dual circuit brakes have a dual/tandem master cylinder and a dual-chamber reservoir.

What exactly is "dual-chamber reservoir"? Does it imply two separate reservoirs for each circuit? My car has a single reservoir, and I guess it must be shared by both primary and secondary system. Each of them may be consuming reservoir fluid independently in parallel, such that leakage in either half can make it empty. Right??
(It is not clear from figures/description in the service manual, as to how exactly each master-cylinder draws fluid from the reservoir)

Leakage in one wheel's piping can drain half of the system, but the other half stays fully functional.

This is what I understood/expect.