Hi guys so im a college student studying Motor Mechanics and have picked up a beautiful Mk 2 Escort as a project. The car doesnt require much work as it is in pretty good condition however im struggling with the brakes. I got the car from the previous owner and all i was told was, the booster had been rebuilt and the brakes need to be bled. After bleeding the brakes with Dot 4 (yellow thick) fluid that was already in the reservoir we got very good pressure and pedal got hard when pumping. Then because of said pressure, i discovered that both front brake lines were leaking so i bought new Capri lines that were just a little longer than the originals but same threads etc. Ever since i replaced them, things went downhill. Bled the brakes after installing the new lines and never got the same pedal feel or stopping force as before. Had been topping up the reservoir with half empty bottles of different brand fluid but all of them Dot 4. Did some inspecting on the rear drum brake pistons and found that the seals on the inside of the assembly were shot and was allowing fluid to pass through and kept popping off the rubber boots on either end of the pistons. Replaced those with 2 new complete pistons and bought a cheap “clutch and brake fluid” which to me sounds like a very generic fluid. This fluid was very runny (low viscosity) and almost clear in color. After bleeding and bleeding with the new parts on and this fluid still no luck with getting the pedal to feel harder and almost no stopping power when test driving it. However when pumping, the fluid does squirt out of the bleeding nipples nicely when opening upon pedal being held down during bleeding process. Could the fluid be the problem? Does the viscosity of the fluid affect building up of pressure ? Could it be my master cylinder ?

Would appreciate any productive advice or things to try

thanks, Ethan

 

Hi Ethan,

From what you described ,at least to me, it seems there is some contamination in the entire brake system in which case you should consider a complete rethinking on this.The only difference between DOT3 from DOT4 is the higher boiling point. Don't know if replacement parts are available, but starting with the master cyl, I would open it up and make sure the rubber components are not swelled or scored. They can be flushed or cleaned with regular clean DOT3 brake fluid. If all the parts are satisfactory you can eliminate that from your project list You probably will need to invest in a gallon can of brake fluid If someone added the wrong fluid to the system you will now need to run some of that fluid through the front brake lines to clean them out. You will need to do the same thing to the wheel cyls or calipers. as you did to the master cyl. Once you have the master and front hydraulic parts where they should be now move on to the rears. You need to flush those lines with clean brake fluid before tackling the wheel cyls. Any leaks will require new rubber parts and sometimes if the wheel cyls were without any pitted bores you could replace the cups , expanders and spring and covering boots and then proceed to bleeding them. You can use little plastic caps on the disconnected lines to prevent them from draining and allowing air back into the system..
Part availability will dictate how far you can go with this , but brakes MUST be right and MUST work as designed . Once you know the hydraulic system is good you can move on to other areas if necessary. Hope I didn't bore you with all this .