brake bleed hell
More Turbo
Joined: Jan 2016
Posts: 535
Likes: 42
From: Scotland
So pedal goes soft when you start up. What about when you switch off? Soft again? And does pedal come back after you pump it?
Also when you start hold pressure on the pedal. The pedal should sink a little.
Also when you start hold pressure on the pedal. The pedal should sink a little.
Senior User
Joined: Apr 2018
Posts: 153
Likes: 0
From: Des Moines, IA
Where is you master cylinder located? On the firewall or below the cab? Mine is below the cab and I was having tons of pedal feel problems. I was having to pump the brakes before I even got pressure. I had to install residual pressure check valves to fix this. As I remember it, when mounted on the firewall gravity is enough to hold the pressure in the lines but if mounted under the cab, the master cylinder is below the wheel cylinders and it causes fluid to flow back into the master.
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Laughing Gas
Joined: May 2015
Posts: 826
Likes: 21
From: Golden, CO
I'll have to try again to see what happens after vehicle is turned off — didn't check pedal afterwards.
MC is on the firewall and also have residual and proportioning valves installed.
MC is on the firewall and also have residual and proportioning valves installed.
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Laughing Gas
Joined: May 2015
Posts: 826
Likes: 21
From: Golden, CO
After some Google research, I isolated the MC and in fact found that this one was leaking, too… from the port, just as the first one (but on the other side).
I've got a(nother) new one on the way from Speedway — hopefully the third time is a charm!
I've got a(nother) new one on the way from Speedway — hopefully the third time is a charm!
Fleet Mechanic
Joined: Sep 2018
Posts: 1,529
Likes: 534
Make sure you bench bleed it really well. Push like heck on the piston until every tiny bubble is out. As it gets harder and harder to push just really lay into it so you are sure you are getting the air out of the forward reservoir. You really need decent leverage.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Exactly. Come back in an hour or two, and can get a little bit more. Let it sit overnight, and there will be some more to bleed off.
Fleet Mechanic
Joined: Mar 2007
Posts: 1,532
Likes: 29
From: northeast Ga
I had the same type of issue , could not get a good pedal . after much aggravation ,it turned out to be the arm the pedal was attached to .I had mounted the master on the fire wall and extended the pedal arm to bring it lower , this changed the leverage , and I was over riding the master , so when the motor was running and with the longer lever it would go to the floor . after changing back to stock length the problem went away
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