Losing brake fluid - no obvious leak

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OllieT
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Losing brake fluid - no obvious leak

Post by OllieT »

Hey all.

Recently did a full brake system refresh. New discs, new pads, refurbished caliper on all corners and new fluid. I bled the system, waited overnight and bled the system again. A lot of air came out the first time, almost none the second time.

Drove around 50 miles today and the brake fluid level went from Max to Min, and the warning light came on. There are no obvious signs of leaks on any of the hoses or calipers.

It's worth mentioning that when I came to the end of my journey, I turned the engine off and pumped the brake pedal a few times.. I could hear the sound of hissing air from what seemed to be the NSF wheel! The pedal went very hard and unable to depress it, back to normal after engine on. Unsure how important that is.. no signs of fluid leaks, but the fluid must be going somewhere for the level to drop!

I did some quick research and came up with all sorts about fluid leaking from the master cylinder into the brake booster.. but I've never done any work on the MC or booster end of a brake system so tbh don't understand what could be happening there! Any ideas??🤔


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abovetherim
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Re: Losing brake fluid - no obvious leak

Post by abovetherim »

First check all the hard lines. These cars are old and one could have corroded.

Next, yes the master could leak past the seals into the booster.
When you did the bleed did you do the 2 man pedal pump method? Reason I ask is it is not unheard of that by pushing the pedal to the floor the master plunger is going past its normal travel and therefore a part of it the doesn't normally run past the seals could be corroded and ruff and can damage the seals.

More likely though is a hard line or one of the caliper seals. I refurbed my rears before and the new piston seal in the kit wasn't quite right and leaked.
1991 rev 1 T Bar n/a 3sge import. A work in progress!!!
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Topic author
OllieT
Posts: 52
Joined: 20/02/17 11:59
Years of MR2 Ownership: 3
MR2's Owned: 1
Real Name: Ollie
Location: Nomad

Re: Losing brake fluid - no obvious leak

Post by OllieT »

Culprit found! Went out this morning to two nicely formed small puddles of brake fluid under the NSF and NSR calipers :facepalm:

I obviously didn't seat the gaskets correctly.. fed up of messing about with them so just going to buy new refurbed ones soon.

Brake booster/MC definitely working okay after following some checks I found online. And for closure I used 1 man gravity method of bleeding.

Cheers for the help anyways😁
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