[santosh.s]

Originally Posted by anupmathur

On the steep gradients and bad roads the oil from the filled up half of the reservoir kept getting splashed into the empty portion and getting lost.

That makes sense, it is quite possible especially when driving on steep slopes or bumpy roads. On highways it should be hopefully less serious. Based on this thread, I have drawn following conclusions that everyone should be aware of-
1. Do not take dual-circuit theory for granted, there is some chance, though a slim one, that even a single leak may lead to total failure.
2. You must have handbrake in properly working condition, which is much lesser effective, but it may rescue you in case of brake failure.
3. You must ensure that there is a lot of clearance from brake pedal to floor, it may give you more time to fix the problem after a leak develops (provided it is detected).
4. While all dashboard warning lights are to be taken seriously, the brake warning is particularly important. I wish all warnings were accompanied by an audible buzzer as well. While driving, it is possible that you may not notice a red light, but a sound can not go unnoticed.

OR
Forget everything and just make sure you carry boot full of bananas all the time! Stuff them whenever and wherever required

BTW, coincidentally, I read that 2CV story on it's 50th anniversary!

[anupmathur]

Originally Posted by santosh.s

Forget everything and just make sure you carry boot full of bananas all the time! Stuff them whenever and wherever required
BTW, coincidentally, I read that 2CV story on it's 50th anniversary!

That's about when I'd read it too!
But I am inclined to imagine, that like SS before you, you are taking the bananas too seriously and professing them as a cure-all!!
Application of mind .... remember?!

[sgiitk]

Originally Posted by anupmathur

Brake fluids are hygroscopic. If a can/bottle of fluid has been left standing for long without being tightly capped, the fluid will have absorbed moisture.
This can cause emulsification and will certainly cause lowering of the boiling point of the brake fluid.

The hygroscopic nature of the fluid is main reason why periodic replacement is necessary. It hard braking it is possible for the (absorbed) water to come out as steam which is like air in the brakes.

I did have a friend who drove his car around for four years, had a wheel cylinde rjam, an we found the oil had become a gel inside it.

[SS-Traveller]

Originally Posted by sgiitk

It hard braking it is possible for the (absorbed) water to come out as steam which is like air in the brakes.

I did have a friend who drove his car around for four years, had a wheel cylinde rjam, an we found the oil had become a gel inside it.

I've also seen such gelling of the brake oil due to water sorption, but don't remember such a thing happening after DOT3 fluids were introduced (around the same time as Marutis came to India). Vapour formation in the wheel cylinders under repeated hard braking can lead to "brake fade" - can happen even if the brake oil itself starts to boil. That's the main reason why downhill drives are to be done in gear using engine-braking, rather than depending on the brakes completely all the time.

[santosh.s]

Originally Posted by SS-Traveller

Vapour formation in the wheel cylinders under repeated hard braking can lead to "brake fade" - can happen even if the brake oil itself starts to boil.

Can you please elaborate- What is it and how does it happen?

[SS-Traveller]

Originally Posted by santosh.s

Can you please elaborate- What is it and how does it happen?

Heavy braking causes heat generation (can even be 500 deg C), which in turn does two things - heats up the brake oil, and cooks the brake shoes/disc pads. Poor quality brake oils or old oils which contain hygroscopically absorbed water, will boil at these super-high temperatures and form vapours inside the wheel cylinder - since vapours/gases are compressible, the hydraulic effect of transferring your foot pressure from the master cyl to the wheel cyl does not happen. As a result, even when you stand up on the brake pedal, a faded brake refuses to stop the car. Also poor quality shoes/pads can "melt" and lose their frictional properties, leading to fade.

Brake discs, ventilated discs, drilled discs etc. were inventions only to prevent brake fade by exposing more surface area to the airstream - otherwise, drum brakes are equally good at stopping your car.

Check the information at Brake fade - Wikipedia, the free encyclopedia.

[santosh.s]

Since I have been physically checking brake fluid every day, I thought of waiting for some more time and watch. It has been over 5 weeks now, and there is not even a single mm of drop! So, I conclude that there is no need to do anything for now. If still there is any possibility of onset of a leakage in that cylinder, then I think that should be equally probable for rest 3 cylinders as well! Will consider brake overhauling 2 years later (when next fluid replacement will be due).

I have stopped making manual checks now, but I do check dashboard lights before every start (well, almost), as per my good habit, and manual check before long trips.

Thanks for all the responses!!

[anupmathur]

Originally Posted by santosh.s

I have stopped making manual checks now, but I do check dashboard lights before every start (well, almost), as per my good habit, and manual check before long trips.

And what are your views about keeping some bananas in the car, for contingencies, LOL!!?

Seriously, your car's brake system seems to be in satisfactory condition presently. All the best!

[santosh.s]

Right now I am busy getting a subwoofer to be kept in the boot, no space for bananas!

[JediKnight]

Rousing an old thread and re-posting my message from another thread:

Hi Guys,

I gave my car to service to Pride Honda Nanakramguda service station in Hyderabad. This is the first time i am getting the car serviced in Hyderabad. Previous all services have been in Bangalore ( Whitefield and Saffire Honda ).
Due to Covid i opted for a pick up and drop. Usually i always drop the vehicle myself.

Apart from the usual stuff the service advisor mentioned that the brake master cylinder is leaking oil and the master cylinder and the booster needs to be replaced urgently. He mentioned it as "big" leak and could cause a brake failure.

This came as a surprise to me since the car was braking perfectly. I monitor the fluids of my car regularly and i would have noticed a big drop in brake fluid. Taking his advice with a pinch of slat i told him to return the car and decided to do a bit of a investigation myself before getting the parts replaced. I had a feeling that this guys was trying to meet his "monthly targets" at my expense, but i could not take this lightly since brakes are a critical safety component.

After receiving the car i did a visual inspection of the master cylinder as well as the brake pedal area. It was absolutely clean and dry. No hints of even a wet patch. I took the car to a safe area ( empty road ) and tried several hard brake scenarios. The car performed perfectly. I precisely noted the brake reservoir fluid level. Did not even go down a mm. I also noted if there are any oil spills below the car after an overnight park. There were none. Did a casual scan of the brake lines, whatever i could see without the car lifted up. Did not see any leaks. I also checked if the brake pedal slowly sinks to the floor when pressed. It did not.

Since there are no visual leaks, my guess is the only valid scenario could be:

1. Master cylinder leaking oil into the booster. Ruled out since in that case i should have seen some reduction in the reservoir level.

2. Master cylinder internal bushes shot. So the cylinder not generating enough pressure on the brake lines. But in my experience the braking looked adequate. But how do you precisely measure this? May be compare it with the braking on a brand new car ? But anyway this should not cause a catastrophic brake failure ? May be a reduction in brake force.

What else can be checked ?

What can be the next steps:

1. Show it to a different Honda service center.

2. Show it to FNG. Since i am new to Hyderabad any recommendations would be welcome esp. near Gachibowli/Hi-tec city area.

[a4anurag]

Originally Posted by JediKnight

1. Master cylinder leaking oil into the booster. Ruled out since in that case, I should have seen some reduction in the reservoir level.

+1. If there is any kind of leak in the whole system, the reservoir level will show the drop.

Originally Posted by JediKnight

2. Master cylinder internal bushes shot. So the cylinder not generating enough pressure on the brake lines.

If there is a loss in pressure due to some kind of seal damage, the brake pedal feels be an indicator for it. If the pedal is firm and not spongy, then nothing to worry. If you still feel the need to check the booster condition, try these:

Test 1: Run the engine for a minute and then stop it. Press the brake pedal multiple times and while doing this if the pedal stroke decreases, the booster is fine.

Test 2: With the engine is OFF, press the brake pedal multiple times. Once the pedal is hard and doesn't push in the press and hold the pedal as is and then start the engine. Once the engine has started, the pedal should move inwards slightly. If it does, the booster is good.

Test 3: With the engine running, press the brake pedal and so the engine. Hold the pedal pressed for 20-30 seconds with the engine is OFF. If the pedal height doesn't change, a booster is in good condition.

PS: Picked the above mentioned tests from my Creta's service manual.

[JediKnight]

Originally Posted by a4anurag

Test 1: Run the engine for a minute and then stop it. Press the brake pedal multiple times and while doing this if the pedal stroke decreases, the booster is fine.

Test 2: With the engine is OFF, press the brake pedal multiple times. Once the pedal is hard and doesn't push in the press and hold the pedal as is and then start the engine. Once the engine has started, the pedal should move inwards slightly. If it does, the booster is good.

Test 3: With the engine running, press the brake pedal and so the engine. Hold the pedal pressed for 20-30 seconds with the engine is OFF. If the pedal height doesn't change, a booster is in good condition.

PS: Picked the above mentioned tests from my Creta's service manual.

Test 1: Passed.

Test 2: Passed.

Test 3: Passed.

I guess this guy is bluffing me. Pride Honda called for a feedback. I told them i am not happy. After that i got a call from the service advisor. He said bring the vehicle. He will "open it" and show me.

I wonder what will he "open" and what will he "show" me. What bugs me is that is he is not able to give me a clear technical explanation of what is wrong. He mumbles something like there is a "big leak" and it is critical and can cause a break failure. When i ask him where exactly is the leak he is not able to explain. Either he is bluffing or has very poor communication skills.

[a4anurag]

Originally Posted by JediKnight

Test 1: Passed.

Test 2: Passed.

Test 3: Passed.

Since the level in the reservoir is as it was, no drops or wetness anywhere around the engine bay or car and braking is good too, I'll say ignore the "big leak" thing from the ASC.

In case anything goes wrong after they try to fiddle around, it'll be even more pain to get things right.

[JediKnight]

Originally Posted by a4anurag

Since the level in the reservoir is as it was, no drops or wetness anywhere around the engine bay or car and braking is good too, I'll say ignore the "big leak" thing from the ASC.

In case anything goes wrong after they try to fiddle around, it'll be even more pain to get things right.

Wondering if i should get a competent FNG look at it for peace of mind. I would have let it go if it was not such critical safety system.