vacuum brake assist

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Mar 29, 2004 | 01:42 PM

weldboy

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vacuum brake assist

Hello. I was Getting a load of hay this weekend and all of a sudden while trying to stop I darn near had to stand on the pedal to stop! It felt like I was braking without the engine running. I tried to do a little reseach and found that the belt driven vacuum pump assists in braking. I took the vacuum line off the brakes and with the engine running felt some suction, but not a whole lot. How much suction should I get? Is this my problem or is it something else with my brakes? checked my brake fluid...good. also, brake light stays on on the dash. anyone else had problems like this? Any help I would sure appriciate it! Thanks in advance.

Jeff

Mar 29, 2004 | 01:43 PM

weldboy

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Sorry, dont know why my signature didnt show up. its a 96 F-250 PSD.

Mar 29, 2004 | 06:24 PM

Ggg6

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From: Northern IL

Sounds like classic vacuum pump going out. It should pull 15-22 inches of vacuum at idle. anything less is bad. Autozone, and NAPA have the pumps, do not pay more then $100. You will need to pull the old pulley off and install onto the new pump. NOTE* Before installing pulley on new pump put the mounting bolts into their holes otherwise you will not be able to get one of them in the hole with the pulley on. Takes about 1/2 -3/4 of an hour to do, no big deal.

Mar 29, 2004 | 06:56 PM

Dieselman929

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From: Eastern PA

My 97 PSD just started to do the same type of stuff this winter...thought it was the cold but....now if I really lean on the brake pedal while stopped, the brake warning light comes on. If I give it a few extra rpm's the light goes right out. Thanks for the tip on the bolts-before-pulley !

Mar 30, 2004 | 06:12 AM

weldboy

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Thanks for your help! It is much appriciated.

Jeff

Mar 30, 2004 | 09:14 AM

Ggg6

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From: Northern IL

No problem glad I could help. Might as well change the serpentine belt while you got it off, and put the old one in the back as a spare.

May 20, 2004 | 05:54 PM

timo944

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From: Atlanta, GA

I had the same problem this week - I measured about 20 in. of vacuum at idle, but when I pressed the brake pedal a few times the vacuum goes down to about 5 in.So I changed the pump and it's doing exactly the same thing. Is it the booster? The other thing that worries me is that there is a little "bubbling" in the resevoir when the pedal is depressed - not much, just a little. I'm wondering if vacuum is somehow leaking into the master cylinder?

Any tips much appreciated.

Timo