went and got a set of motorcraft brakepads.... my haynes manual says i need to drain brake fluid... is this true?

thanks

 

Usually they want you to watch the fluid level in the in the master cylinder because you will have to compress the brake calipers to put in the new pads, thus causing the fluid level to overflow if it was full at the start. You never want to drain it too low or otherwise you could get air in the lines. Whenever i have done the pads i always flush out the old fluid.

 

It is good idea to bleed the the caplier in order to compress the piston.. I read somewhere if you don't, you might damage the abs system.. But, you should replace your brake fluid every few years anyhow.. (the system builds up moisture otherwise)

 

I don't. I open the cap on the MC and then compress the caliper with a big c clamp.
I do flush the fliud every few brake jobs. I am to the point where I replace the calipers every two or three brake jobs. There have been too many problems with the rears of these SD trucks. I ruined a set of PowerSlots bc the caliper came apart on me. Hmm...maybe I should drain the brake fluid

 

I'll learn from your experience slflem... thanks

how much brake fluid should i get... is plain ol dot 3 good enough

 

I got three of the smaller bottles and that was plenty. I believe DOT 3 is fine. DOT 5 is silicone based and should not be used. Another thing to think of is brake fluid absorbs moisture being hygroscopic in nature, so the boiling point lowers as a result of water being absorbed... Should flush every 2 years or so.

 

I just did mine -- took about a quart and a half of Dot 3/4 syn. I used Valvoline.

 

Back in the days before ABS, it would be no problem not to break loose the bleeder valve when compressing the caliper piston.. Did a google search and found many links saying basically the same thing.. here one of them... quote:

Question:
I should open bleeders on calipers while I push the piston back so that the contaminated brake fluid don't back up into the ABS system and do harm to the pressure valve and the mechanical ABS unit and that's its wise to crack open the bleeders so that contaminated brake fluid don't back up in the brake line and go to the ABS unit.

But I also heard that I don't need to do that but the mechanics that I talk to here say I should to prevent trouble coming back in the future with the ABS system. Now I been opening the bleeders and bleeding the systems before I do brake pad and shoe replacement and I was told too that some times its good to bleed the system to clean out all the contaminated fluid that it don't hurt to do that as well.

But I mainly like to know is that true about opening the bleeders before doing brake service and then closing them once the piston is back all the way and almost same with rear drum shoes and wheel cylinders.


Thanks for any help,
Henry

Answer: Opening the bleeders on the calipers and wheel cylinders when you compress them is the right thing to do. You don't want to push back any debris that has accumulated in the system back into any of the ABS components or brake master cylinder.