Re: Interesting recall

Posted by HH56 On 2019/3/4 12:21:32

I am speaking of the DOT 5 fluid which is silicone based.

As you may remember a few years ago many recommendations were to drain the DOT 3 and 4 fluid which is hydroscopic. The older fluid tends to corrode or deteriorate brake systems if ignored because the fluid attracts moisture over time which leads to the issues. Theory was if replaced with the 5 fluid which did not attract moisture it was thought there could be a longer term no maintenance and storage option for cars which did not see much use.

Of course all did not go as planned and because of the incompatibility of the fluids, there were lots of issues and even some failures with systems that just had the old fluid drained and then replaced with 5 and no flushing or cleaning step in between. Because of that I don't believe there is as much thought going into replacing the 3 and 4 fluids now.

Properly done it seemed and probably still is a viable option but the reports began coming in that the brake switches suddenly failed shortly after the fluid changes. Many just chalked it up to the old switches finally meeting their expiration date but I believe failures are still somewhat of an issue with those running DOT 5 even with new switches. Some with failures have converted to mechanical switches and others have just replaced the hydraulic switches as needed.