What happens when you mix silicone brake fluid with the DOT 3?

I bought a vehicle that the fellow said had synthetic fluid. Did a little work on the front end and had to bleed the brakes. Topped off the master cylinder with silicone and it looks like almost oil and water. The new & old didn't blend, or appear to anyway.

What happens when you do that?

 

Not good. The two are not compatible.

If it was me I would purge the system using alcohol and refill with fresh fluid. At least I would know what's in there.

MikeyB

 

Thats what I was afraid of. I took it for a test drive and it acted fine but when the purple silicone didn't immediately dissolve into the original yellow stuff it made me start wondering.

 

I would try and siphon off what is in the master cyclinder rather than working it thru the system if you can. None of the silicone fluid may have made it into the system.

 

Like JP said. Remove what you can with an old turkey baster, replenish with the correct brake fluid and then bleed the brakes until it comes out as clean as the stuff you just put in the reservior. Niether fluid is going to hurt or damage the system. The mixture will most likely change the boiling point of the fluid and cause erratic operation when the system is really taxed. I would just flush it really good with the correct fluid A.S.A.P.