Brake Proportioning Valve
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Cross-Country
Joined: Jun 2021
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Brake Proportioning Valve
Yay!!! More brake fun for me.
93 F250 4WD 7.5L 5-spd.
Everything but the hard lines and ABS unit are new.
Basically when I start out in the morning the truck drives great, brakes feel as they should. As the truck gets warmer the brake pedal starts getting more and more wooden. Brake performance isn’t noticeably lessened, but effort to push the pedal is noticeably increased.
My preliminary research has led me towards the brake proportioning valve… does this seem reasonable? I don’t believe it’s a booster issue, as I can still hear the “whoosh” of the booster when I hit the brake pedal.
As always, any advice is greatly appreciated.
Be Safe
Jeremy
93 F250 4WD 7.5L 5-spd.
Everything but the hard lines and ABS unit are new.
Basically when I start out in the morning the truck drives great, brakes feel as they should. As the truck gets warmer the brake pedal starts getting more and more wooden. Brake performance isn’t noticeably lessened, but effort to push the pedal is noticeably increased.
My preliminary research has led me towards the brake proportioning valve… does this seem reasonable? I don’t believe it’s a booster issue, as I can still hear the “whoosh” of the booster when I hit the brake pedal.
As always, any advice is greatly appreciated.
Be Safe
Jeremy
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
I agree. That sounds like a booster problem. It's interesting that it gets worse as the engine warms up. This leads me to believe that it might be an after market vacuum hose collapsing as the rubber gets warm and looses it's strength.
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Cross-Country
Joined: Jun 2021
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Okay. That’s easy enough to diagnose with a vacuum gauge. I’ll start there. Thankfully, while the problem is intermittent, once it starts it stays until things cool down. Bad vacuum hose routing or a hose collapsing seems reasonable.
Thanks
Jeremy
Thanks
Jeremy
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
Once you shut down the engine, the vacuum is removed from the hose and it can bounce back to it's normal shape. As the engine cools, it regains it's strength until you start it up vacuum and heat returns, and the cycle repeats itself.
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