repair/replace brake fluid reservoir "strainer with float"

[vairter]

I've been having issues with the dashboard brake light indicator flickering.  When I looked inside the fluid reservoir, I found that the float had partially filled with fluid and the shaft had separated from the float cylinder.  Here is part I'm referring to, from an earlier thread on the subject :

 

https://www.bmw2002faq.com/forums/topic/99084-should-the-brake-juice-float-be-attached-to-strainer/

 

 

The black rubber part on mine has significantly degraded, so I'm pessimistic that it can be rehabilitated well enough to prevent fluid from entering the float in the future.  But I'll give it a shot.  How have others gotten the fluid out of the float?

 

It looks like this original part is NLA, but there seems to be an alternative that is available for other BMW's:

 

https://www.rogerstii.com/bmw-brake-fluid-reservoir-cap-2002-3-0cs-630csi/

 

Has anyone tried this alternative?  There is no integral strainer and you have to replace the cap, but it may be the only way to go.

 

Terry

 

 

[Stevenc22]

I believe there is a modern alternative

 

390427 BMW Brake Fluid Reservoir Cap with Warning Switch ATE 34321153156

WWW.EUROPARTSPLUS.COM

---

BMW Brake Fluid Reservoir Cap with Warning Switch ATE 34321153156, ATE part number 390427. SKU 34321153156-MFG4. Fast shipping, 3-year warranty and U.S. based customer service. Order today!

 

[vairter]

Steven-

 

Thanks.  That is probably a more reasonably priced version of the one I cited on rogerstii.com.  You saved me $13.

 

Has anyone used this modern alternative without regrets?

 

Terry

[Son of Marty]

I'd think you'll be fine with out the strainer, I mean if there's crap in the brake fluid then it's garbage anyway, just wipe the top of the reservoir if it's dirty. 

[Mike Self]

My float went down with all hands a couple of years ago; fortunately I had an old reservoir in my parts stash so just swapped out. 

 

Just for the heck of it, you might try McGyvering a repair:  find some lightweight solid material--plastic or even a wine cork (coat with urethane or shellac) to replace the hollow float.   You might even adapt a gas gauge sender float that will fit.  

 

Back in the day before plastics, gas gauge sender units used shellac-coated corks as the float.  Those in my 75 year old Fiats and Renaults still function just fine.  But whatever you try, make sure it doesn't deteriorate in brake fluid before committing.  

 

mike

[conkitchen]

Had the same issue. The hole in the center where the black rubber stopper is developed the leak. Poked another small pin hole in the side and blew out the fluid with the air nozzle. Then used RTV gasket sealer in the center and stuck the black rubber stopper back. Then with a solder iron (hot) I resealed the pin hole.  

 

But hey I'm like them old farmer guys who made it work instead of buying new.  

[vairter]

conkitchen-admirable effort, but will the RTV contaminate the brake fluid?

[dlacey]

In the Jaguar world we break out a good bottle of wine when this happens. Half a wine cork in-place for your float will work fine for many years...even the synthetic corks seem to work fine in this application....

[conkitchen]

5 hours ago, vairter said:

conkitchen-admirable effort, but will the RTV contaminate the brake fluid?

Silicone once cured should be inert, 

 

FWIW: https://www.permatex.com/wp-content/uploads/tds/85084.pdf says use in glycol-water based products as well as other engine based fluids like oils. It does say not to use in gasoline applications.  

 

Brake Fluid DOT 4 is a complex mixture of polyglycol ethers, glycol ether borate esters and polyglycols with additional corrosion and oxidation inhibitors.

 

The area of use is in your application would be very limited and sorted covered up by the rubber stopper. 

 

see tagline below

Edited October 8, 2023 by conkitchen

[JohnS]

On 10/7/2023 at 1:45 PM, vairter said:

Steven-

 

Thanks.  That is probably a more reasonably priced version of the one I cited on rogerstii.com.  You saved me $13.

 

Has anyone used this modern alternative without regrets?

 

Terry

Yes.  Both of my cars are sporting the newer white cap version.  I kept the original black ones because I'm a hoarder 😄

Edited October 10, 2023 by JohnS