Braking Situation
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Freshman User
Joined: Sep 2011
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From: Troy
Braking Situation
I replaced my rotors and brake pads in June ($500 in parts
). Since then the brakes have worked good. Stops very well for a big 250, but lately I have had a problem with the front drivers side tire locking up if I apply a decent amount of pressure to the brake pedal. The problem only persists for less than the first 5 minutes the truck is running. Scared the crap out of a guy in a crosswalk this morning (last thing you wanna hear while in a crosswalk is a big 250 skreeching to a halt 6 feet away. 
). So I am thinking it may have something to do with it taking a little while for my truck to build up vacuum. When the pedal feels like i have full power brakes the tire doesn't lock up anymore but when they are still stiff it acts up. Would vaccuum leaks be a possible cause?
). Since then the brakes have worked good. Stops very well for a big 250, but lately I have had a problem with the front drivers side tire locking up if I apply a decent amount of pressure to the brake pedal. The problem only persists for less than the first 5 minutes the truck is running. Scared the crap out of a guy in a crosswalk this morning (last thing you wanna hear while in a crosswalk is a big 250 skreeching to a halt 6 feet away. ). So I am thinking it may have something to do with it taking a little while for my truck to build up vacuum. When the pedal feels like i have full power brakes the tire doesn't lock up anymore but when they are still stiff it acts up. Would vaccuum leaks be a possible cause?
Laughing Gas
Joined: Apr 2011
Posts: 1,002
Likes: 7
From: London, KY
Yep, I believe it would. I'm needing a vacuum pump as well and my brake pedal feels like mashing on a concrete block and it has very little stopping ability when it's like that. I checked my vacuum pump with a vacuum tester and it was only pulling 10-12 PSI and it should be up around 20 at least.
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From: Troy
Well thanks for the confirmation.
I'm not exactly sure why lack of vacuum would cause it to lock that tire up but I just figured since it didn't do it once vacuum seemed to build up that would be the cause.
My pump is around a year old so i don't think the problem lies with the pump itself but with the vacuum system. I'm pretty sure it leaks because sometimes when I'm at a stoplight my A/C will begin to blow through the defrost. And perhaps that my system has duct tape on it in a few areas and seems to be pieced together.
On a gas motor I always use WD-40 or starter fluid to check for vacuum leaks, but I know on a diesel that won't cut it so is there a trick similar to that you know of to find them for a diesel?
I'm not exactly sure why lack of vacuum would cause it to lock that tire up but I just figured since it didn't do it once vacuum seemed to build up that would be the cause.
My pump is around a year old so i don't think the problem lies with the pump itself but with the vacuum system. I'm pretty sure it leaks because sometimes when I'm at a stoplight my A/C will begin to blow through the defrost. And perhaps that my system has duct tape on it in a few areas and seems to be pieced together.
On a gas motor I always use WD-40 or starter fluid to check for vacuum leaks, but I know on a diesel that won't cut it so is there a trick similar to that you know of to find them for a diesel?
Logistics Pro
Joined: Dec 2005
Posts: 4,644
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From: Moro Bay, AR
The problem is the replacement pads you used. When I replaced the front brakes on my 94 F250, I used some cheaper organic pads from the local parts house and had the same problem you are experiencing. I changed to a premium semi-metalic pad and the problem went away.
I think the reason you are just now having problems is as it was explained to me, the pads absorb moisture overnight and it takes a few applications of the brakes to boil off this moisture. Nights are getting cooler and there is more moisture in the air.
I think the reason you are just now having problems is as it was explained to me, the pads absorb moisture overnight and it takes a few applications of the brakes to boil off this moisture. Nights are getting cooler and there is more moisture in the air.
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From: Troy
Well that may be a reason why? But I used the best pads and rotors I could buy. Wagner Thermo-quiet. I go all the way with brakes. Acceleration may be cool, but brakes save your life.
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From: Troy
I bought the flex lines for the front a WHILE back, but never installed them. I'll try and dig them up. If I find them i'll throw them on ASAP
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Postmaster
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This is how i tested my vac pump.
You will need to isolate all the vac lines.
You will need to isolate all the vac lines.
Well today i got a vac gauge and tested my pump. at idle it pulled 25 inhg. then i hit the brake pedal and the vac droped to about 10 inhg. when i released the brake pedal it took mabey 30-35 sec to build back up to 25 inhg. if i hit the brakes three times the vac would go all the way down to about 5 inhg. it took even longer to build up. i isolated all the lines and discovered that i did not have any leaks so i came to the conclusion that my vac pump is bad.
Logistics Pro
Joined: Dec 2005
Posts: 4,644
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From: Moro Bay, AR
You probably used the MX450 pads, I think I went with a SX450 to fix the problem.
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