Brake Fluid Refill Interval

LancerL · December 3, 2015

I'm so sorry if this is a re posting but I could not find any solution by searching on forum.

Yesterday night I found that my check brake light has suddenly pops and goes off in the dashboard time to time while I was driving.

When I got back home I checked the brake fluid level and found that it has gone to the Min mark of the reservoir (The gap between Max-Min is about less than an inch)

But as a total tank capacity the lost amount is also less than 1/4 of the full tank capacity.

I did a full brake fluid flush with B*G Dot4 8months back with brake washers replacement and filled up to the Max level after job done which is 100% sure.

Also did a washer leak check about a month back at the service station and there was no leaks found.

Will this could be due to gradual evaporation through 8 months of not refilling or could be due to a minor leak? If it is a leak there should be air sucked inside and the paddle should be spongy?

I don't feel any strange in paddling and the braking power of the car.

Please help.

LancerL · December 3, 2015

Found the issue!

There is a tiny leak between the master cylinder and plastic reservoir it seems.

Yesterday engine was damn hot and couldn’t touch that area, but today I touch under the master cylinder and found that there was some fluid.

Last time also I experienced the same issue soon after replacing the master cylinder and the reason was that two plastic nozzles of reservoir are not tight enough with master cylinder holes.

Ultimately they brought two screw type nylon washers from a lath shop, which filled the gap and fixed.

Looks like same place start leaking.

Is nylon melt down for brake fluid?

If that is the case, what's the best adhesive to use which doesn’t react for brake fluid?

Anyway I will be opening a new thread to get some advice on brake fluid resistant adhesive as the topic moved in to a different direction. http://forum.autolanka.com/topic/17436-brake-fluid-resistant-adhesive/

Thank you all for the prompt support!

Edited December 3, 2015 by LancerL

Rumesh88 · December 3, 2015

Replaced washers in master pump too? If the leak is from the master pump and if it is minor you would not notice a spongy pedal. Just check for possible oil leak near the master pump mount. The level drop is definitely not due to evaporation but could be due to (premature) wear of brake pads if the car was subjected to high mileage and hard braking.

NRX · December 3, 2015

Also are you certain the service station guys did not muck up the brake washers in the process of checking them ?

LancerL · December 3, 2015

Also are you certain the service station guys did not muck up the brake washers in the process of checking them ?

Ya I'm sure I was observing them while checking.

LancerL · December 3, 2015

Replaced washers in master pump too? If the leak is from the master pump and if it is minor you would not notice a spongy pedal. Just check for possible oil leak near the master pump mount. The level drop is definitely not due to evaporation but could be due to (premature) wear of brake pads if the car was subjected to high mileage and hard braking.

Master pump itself has replaced at the time of flushing brake fluid due to excess wear of one side of the cylinder so the chance of it will be minimal.

Observed no outside leaks.

I was thinking it have evaporated as it is very thin liquid compared to engine oil and the heat of the engine bay. Also absorb water in the air.

Planing to take it to the garage to check brake pads and washers again.

Will keep posted.

Thanks