Brake Question
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Senior User
Joined: Oct 2004
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From: Las Vegas
Brake Question
I recently bought a 97 F350 XLT, 7.3L Turbo PSD, 2WD, E4OD, Dually.
I've had the truck about 3-4 weeks now and yesterday I noticed when I apply the brakes the first time I have a good pedal. If I lighten up on the pedal and apply again it feels like I lost my power brake feature and I need to push hard to stop. The pedal is still solid, just takes a lot of foot pressure to stop.
I was thinking I may be loosing vaccuum. I say that because if I drive for a bit and hit them again everything feels fine. Until I let off and reapply rapidly.
The previous owner told me he replaced the master cylinder once. He may have told me when but I don't remember.
If anyone has any ideas, thoughts or advice I would surely appriecate it.
Thanks
Kevin
I've had the truck about 3-4 weeks now and yesterday I noticed when I apply the brakes the first time I have a good pedal. If I lighten up on the pedal and apply again it feels like I lost my power brake feature and I need to push hard to stop. The pedal is still solid, just takes a lot of foot pressure to stop.
I was thinking I may be loosing vaccuum. I say that because if I drive for a bit and hit them again everything feels fine. Until I let off and reapply rapidly.
The previous owner told me he replaced the master cylinder once. He may have told me when but I don't remember.
If anyone has any ideas, thoughts or advice I would surely appriecate it.
Thanks
Kevin
Post Fiend
Joined: Jan 2005
Posts: 8,402
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Assuming you do have the vacuum booster and not the hydraulic booster then yes, you have a vacuum problem. Now it could be a leak in the booster itself, a faulty one way valve (the little fitting that the vacuum hose plugs on to at the booster), a leak in the hose that supplies vacuum to the booster or most likely a bad vacuum pump. I would get a vacuum gauge connected to the pump and see what it says and take it from there. The pump should put out a min. of 20in. of vacuum. Hope this helps.
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Senior User
Joined: Oct 2004
Posts: 264
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From: Las Vegas
Lazy K,
I put the vac gage on an got a reading of 9 in at idle, and about 13 at 18-2000 RPM. The check valve seems to be working OK, and I don't think the booster is leaking.
After shutting down with gage installed, it will bled down in about 10 minutes.
Anyway I checked the hoses and did not find any leaks/cracks, so I am going for the vac pump.
Thanks for the help and quick reply.
Kevin
I put the vac gage on an got a reading of 9 in at idle, and about 13 at 18-2000 RPM. The check valve seems to be working OK, and I don't think the booster is leaking.
After shutting down with gage installed, it will bled down in about 10 minutes.
Anyway I checked the hoses and did not find any leaks/cracks, so I am going for the vac pump.
Thanks for the help and quick reply.
Kevin
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