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Brake reservoir cap

olyolson

Well Known Member
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I have these brake reservoirs from Acft Spruce mounted on the back of my master cylinders. The right brake sometimes leaks a tiny amount of fluid at the cap and I’ve double checked that the reservoir is not overfilled. I use the breather cap from Vans on both sides and don’t have an issue with the left one. I’d like to replace the cap but they are not available from Vans on the website. Is it OK to use the red plastic cap or are there alternatives?
 

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The reservoir needs to either breathe or have a diaphragm of some sort to prevent negative pressure. two way check valves also ok.
 
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The reservoir needs to either breathe or have a diaphragm of some sort to prevent negative pressure.
Try a brass hose barb fitting with 1/8" NPT. Run the hose upward a few inches and tie wrap it to something. Best to bend the hose downward at the top to prevent ingestion of dust. You can use small hose, as it doesn't move much air. This should create a working fix.
 
Just replaced the filler plugs on the master cylinders of a Cessna 185, during an annual, a few months ago. I believe they were plastic 1/8" pipe plugs. Might be the same setup that you have.
 
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