We replaced the hydro boost and master cylinder on our 2001 Ram 2500 Diesel. After bleeding the brakes we are having issues with the brakes building up pressure. Have to stop on the side of the road and bleed again. This has happened several times. Any suggestions on why this is happening and how to fix it?

 

Could be the push rod on the hydro boost is too long and causing the MC to engage?

 

Do you have old rubber brake lines in the front? Sometimes these can fail inside the lumen of the line and cause a clapper valve like situation where the calipers cannot return to the relaxed position...Mark

 

That could be, but how could I fix this?

 

replace the 17 year old brake hoses with new. They don't last forever, and swelling on the inside is a common problem. So is phenolic caliper pistons sticking. Most likely bad hoses.

 

When I replaced my pads and rotors I compressed the caliper pistons back in. The right one would stick and drag until I replaced the calipers and hoses.

 

I would replace all the rubber hoses. used stainless braided on mine. I couldn't say how to adjust the Mopar booster, I went GM Hydro boost before the famous Mopar master cylinder problems started.

 

I had a brand new hydraulic hose do that once. Under pressure the fluid would get under the liner and close the hose off. with no pressure the hose looked fine and compressed air went through it one way. took a while to figure that one out. lesson learned blow through hoses both ways

 

What booster did you use? With a hydro boost the hoses should be replaced. Hydro boost can put out 2500 PSI where the vacuum booster will put out maybe 1500 PSI.