Brake reservoir oring fail. God I hate surprises.

[svejkovat]

Left work last night and noticed a little puddle beneath the back of the front fender. 

The fender had little lumpy spots all over it.

Eyes moving upward the brake reservoir was empty.

Bike on center stand, wheel cocked to the left.  Fender under the reservoir.  Drip drip on the fender and it spattered enough to ruin paint on the entire back half of the fender.  Bubbles wiped off right down to plastic underneath. 

Pulled the reservoir and the oring was corroded with that hardened resin that results from water contaminated brake fluid.

Having hella time finding brake fluid compatible epdm rubber orings anywhere in west Michigan.  Short of waiting for one in the mail from a dealer.. locating the right size in some other oem application and then giving the parts counter guy a number so he can find the right little white box on the shelf.. or buying a whole kit of epdm rings from harbor freight.

Incidentally, It's pretty demoralizing to discover how many sales people and mechanics have no idea that most O-rings are incompatible with brake fluid. 

Jesus I hate it when some tiny little thing can ruin your week!

My hunch on this is that recently I decided to fill my reservoir with this stuff since it was on the shelf at autozone and it was GERMAN!!!!  What's not to love?



So my reservoir is fine for years.  There is probably something just slightly different enough in the formula of this stuff compared to the prestone that I'd normally use that it got past the already old and failure prone oring. 

Postscript...   is there anything really special about our BMW black that I can't expect a decent match with some automotive rattle-can?   I'm not so excessively worried about the match in this spot.  In fact, it's about the best place you might hope for if you had to face ruined paint.  I've had really good luck in the past with the off shelf Dupli-Color paint.  Good prep, patient spray in a dust free area,  patient wet sand between coats.   

Thanks for the place here to commiserate.

[mrclubike]

 You may want to consider rebuilding the MC

By the way that is the same brand fluid I use and have had no problem yet 
The fact it is in a metal can is good also

At least you didn't drop your fuel tank and put a big ole dent in it like I did 

[tunnelrider]

Man it's annoying when stuff like that happens   At least you've got a plan, I'd be doing that with a rattle can too first.  I don't believe there's anything special about the black except I think it's gloss finish - with a clear coat on top.

You may want to consider rebuilding the MC

I agree, two birds/one stone.

[Barry]

So my reservoir is fine for years.  There is probably something just slightly different enough in the formula of this stuff compared to the prestone that I'd normally use that it got past the already old and failure prone oring.

Brake fluids designated as super Dot 4 or Dot 4 plus etc are usually the modern low viscosity fluids intended for use in ABS systems. They are a lot thinner than normal DOT 4 fluid and perhaps more likely to leak.

Note I said usually. There is no consistent standard on how manufacturers name these low viscosity fluids hence the the variety of different names.

There is no good reason to use these low viscosity fluids in an airhead and I would be inclined to choose a standard DOT 3 or Dot 4 fluid.