R50 Squishy Brakes after a water crossing

[KingKiwi]

Hello Everybody,

 

I have a very green question that I'm hoping some hardcore DIY'ers may be able to shed some light on!

I was doing some offroading and drove into a big old mud puddle. Got stuck, Got out.

But then I realized my Brakes went real soft. Like real soft. and any extended periods of not using the brakes meant that had to pump the peddle a few time before i pot any pressure on the pedal to get any braking power.

 

I got home and bled the brakes, I couldn't see any bubbles in the line, but the fluid was real brown (I think brake fluid goes brown when it absorbs moisture, right?). So the fluid in the system is much clearer at this point and the brakes are much better at this point. They are still a little soft, but no longer requires pumping up. GREAT...ish.

 

Then I go through a water crossing some time later and BOOM, they go real soft again.

 

My initial thoughts are that there must be somewhere where the water is getting in, but then there would be a leak, which i cant see anywhere.

 

Anyone have any ideas?

 

Thanks in advance!

 

[Slartibartfast]

Brake fluid is commonly neglected and usually looks like hell unless something in the braking system was replaced recently or the owner decided to do some preventative maintenance. The fluid absorbs moisture from the air, and the cap is not airtight. Moisture in the fluid is not a good thing (corrosion, lower boiling point), but I wouldn't expect it to do what yours is doing. And, yeah, I'd expect any leak that would allow mud puddle water into the brake lines would blow brake fluid from hell to breakfast.

 

My first thought is electrical. When the speed sensor for the ABS in my '93 started to go, the ABS light turned on pretty much whenever the sensor was wet. The ABS is able to release brake pressure to stop a skid, so I would not be surprised if moisture in a damaged harness or actuator opened the wrong valve and nerfed your brakes until it dried out. If you don't see any obvious damage to the actuator or the harness, I would get a helper to pump the brakes (engine running) while you spray various things with a hose to try and make it act up.

 

Seems like the ABS computer should be throwing a fit (or at least an idiot light) if it was malfunctioning that badly, but I don't know the R50 that well.

 

My only other thought is that you can get a long pedal travel if the rear drum brakes aren't adjusted right. Obviously a tadpole didn't reach in there and spin the adjusters while you were in the puddle, but maybe some mud and debris got in there and did something? Long shot, but if you run out of ideas, pull the drums and make sure everything is in order.

 

Oh, and if you can get it to act up again, see if you can figure out if any of the brakes are still functional. Dual-circuit brakes means a fault in the front can't take out the rears (and vise versa). Might help track it down. Also, when you bled the brakes, did you bleed the load sensing valve as well? That's a bleed point on the US R50, I assume the NZ spec would be the same. I doubt that's the issue, but, might as well get all the goo out if you have to bleed it again anyway.

Good luck! I hate working on brakes.