dieseldoc Posted July 27, 2019 Share Posted July 27, 2019 Morning gentlemen. This 2008 F-350 v10 and auto 4x4 is turning into a real nightmare. Did brakes and ended up replacing all 4 calipers. I sucked most of the old fluid out of the master cylinder and filled with new than teller the calipers all gravity bleed until clean fluid came out. I than bled the calipers all the way around. Than hooked up the service tool and did the brake bleed command twice in the abs module. I than bled all 4 corners again. Road test and all is good. Sat for two days waiting for parts for another segment on the RO. Go to move it and pedal to the floor. So I do the service bleed with scan tool twice and all is good. Park it and road test twice with a 24 soak each time and brakes are good. Release to customer. He drives it two days without issue. Calls this am and says pedal went quite always and now feels funny. Looking at it Monday, what am I missing?? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted July 28, 2019 Share Posted July 28, 2019 First ? is: was this concern present before you touched it, or did you create it? Assuming this truck is not losing brake fluid, it's hubs and bearings are all tight, caliper and brake pad guides are free I might look at my fluid actuating and ABS components. I don't think I have ever seen an intermittent master cylinder malfunction but never rule it out. I have seen a couple ABS HCU's do weird intermittent things like excessive pedal travel and even locking up rear brakes. It is possible to have a bad dump valve leaking or sticking. Things to consider. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted July 28, 2019 Share Posted July 28, 2019 I'd cap the MC output ports and let it sit a couple of days to see if the problem returns. If I were to guess, I'd hang a MC. Quote Link to comment Share on other sites More sharing options...
dieseldoc Posted July 29, 2019 Author Share Posted July 29, 2019 Thanks guys I will see what we find in the am. The brakes were in terrible shape before I worked on it. Felt a bit soft to me. But the pads were very worn, two calipers had stuck pistons and one had a stuck anchor pin. I replaced the rotors, pads, front wheel bearing assemblies, park brake shoes and backing plates as well as all 4 calipers. Sucked down the master cyl and filled with fresh fluid than let everything gravity bleed until clean fluid came from all 4 calipers. Than ran the abs bleed in scan tool and bled each caliper 3 times. Worked good than after sitting the weekend it felt funny to me so I ran the bleed procedure again and road tested. Sat a couple days and road tested again and brakes were good. Will let you know what I find if it’s jnot something obvious when I get there. I’m super fussy about brakes because of the potential outcome of a problem. I work 90% of the time with air brakes so wanting to cover all my bases on this one. Quote Link to comment Share on other sites More sharing options...
2006 Posted August 1, 2019 Share Posted August 1, 2019 Did the master cylinder go empty at any time during the service? Quote Link to comment Share on other sites More sharing options...
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