Rinse Out New Master Cylinder?

jrhaelig

jrhaelig

Senior Member
I opened up a new master cylinder, took the fill cap off to inspect before mounting and a bunch of pellets fell out. Casting sand or something. There was some debris sitting down on the piston wall, too.

Should I rinse it with WD40 or something?

If not WD40, what would it be?

Thanks again....................
 
Definitely not WD40.

Sounds bad, but you could strip it down, wash in warm soapy water, dry thoroughly, and pass some clean new brake fluid through it.

I've heard people mention de-natured alcohol, but I have no personal experience with that.

It is bad that it has crud in it, that would have done no good at all if left in.

Mart.
 
Well, master cylinders are easy to take apart. You should probably take the piston out (keeping track of the order the parts come out) and clean it thoroughly. Cleaning it with brake cleaner should be fine. Reassemble it dry if you are using it soon.
 
jrhaelig said:
I opened up a new master cylinder, took the fill cap off to inspect before mounting and a bunch of pellets fell out. Casting sand or something. There was some debris sitting down on the piston wall, too.

Should I rinse it with WD40 or something?

If not WD40, what would it be?

Thanks again....................
Click to expand...

Do NOT use any petroleum based cleaners on internal hydraulic brake parts. Isopropyl or denatured alcohol is the best to clean with, then rinse with the brake fluid you will use.
 
Ummm... WHERE did you get that master cylinder? What brand? Please tell...
And yes, alcohol... If you had assembly lube, specifically made for brake parts, that would be cool...

Karl
 
This is a new M/C from MACs - manufactured in Venezuala.

Probably the same unit received by all catalog vendors.
 
Second on dissassembly and cleaning with alcohol then soak the parts in fresh brake fluid. Wipe down the parts and reassemble. Venezuela. I've used some rebuilt MCs and WCs from China that were spotless. Like you I tend to check every thing before it gets installed.
 
My 40 master cylinder was Made in America by Wagner. Got it from Joblot 2 weeks ago. Reservoir was full of metal chips. Had to completely disassemble to clean it out. Joblot said this was the first complaint they had. I told them they wouldn't be able to say that anymore. RPM
 
If it was mine, I would send it back with all of its crud and buy a new one from a local supplier that handles Wagner or Raybestos. That way if something is wrong, you don't need to wait weeks for a replacement. The P/N for Raybestos is MC1050
 
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