I went to get an oil change at my usual place last week. The guys there are cool and let me in the shop while they're doing it... i went to the boot to grab my oil filter, and when i came back i watched the "new guy" top off my brake fluid with Dot 3. It wasnt much, but i know a bit got in there... we're talking less than an OZ. or two.

Is this going to be a problem for me down the road? Is it that serious that i should have the whole system flushed out?

I'm not an expert, sorry for sounding paranoid

Mike

 

Yup, its a problem. DOT3 fluid absorbs more water than DOT4, and the system may not compensate. If the water boils, it creates pressure on the pads which will either wear the pads, overheat the brakes, or both. When Mini put the wrong fluid in CVT transmissions a while back, they had to flush them like crazy to clean out all traces of the contaminated fluid. Brakes are a lot easier to flush than a tranny. I'd strongly ask for a flush and an entry in the service record recording the service mistake.

 

If it concerns you, just siphon the reservoir, and fill with the proper fluid type. I don't believe the fluid is circulating throughout the system like oil or trans fluid, plus less than a shot glass full may not be too much cause for concern.

 

Changing the fluid just in the reservoir is not good enough. Dot 3 and 4 are miscible fluids - they mix in fluid mode. Because the brake lines are not recirculating, the lines are now full of the mixed fluid. The proper way to flush is to open the bleed screws and flush new fluid in from the reservoir and out the calipers until all the fluid is exchanged. The problem is the fluid in the caliper and lines, not the reservoir.

 

All I meant was the fluid in question was probably still in the reservoir, and had probably not gone past the master cylinder as the system is not cirulating. But, if they want to flush the whole system, then at least siphon the reservoir first. If not, you may just push the Dot 3 through the system, which may not have been in the lines in the first place.

 

Its always best to siphon the master cyl first. Even if just bleeding the brakes. Gets a cleaner fill in the master cyl. BTW: Any idea as to how to get that little plastic screen out of the reservoir? Its a ***** to siphon with that in place.