Vacuum Pump info needed..
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Vacuum Pump info needed..
Hi guys/girls
Newer to the forum, joined the board to gather info on my inlaws 1998 Ford E350 Cubevan with a 7.3 diesel.
Problem is in relation to the brakes. The pedal is rock hard (as if it has no assist) unless you slip the trans into neutral and hold the rpm's up around 1200. As an ex toyota/lexus mechanic, I diagnosed it as a bad brake booster, as it showed most of the signs/symptoms of a failing brake booster. Today, I replaced the booster, and the problem still exists.
With the engine running, I can pull the vacuum line off the booster, and there is vacuum there, but noticeably less than that of what a gas engine would provide. I'm looking for a vacuum spec I guess. What kind of vacuum should the vacuum pump pull at idle or slightly above idle?
My new thought is that the vacuum pump is not pulling enough vacuum.
Jay
Newer to the forum, joined the board to gather info on my inlaws 1998 Ford E350 Cubevan with a 7.3 diesel.
Problem is in relation to the brakes. The pedal is rock hard (as if it has no assist) unless you slip the trans into neutral and hold the rpm's up around 1200. As an ex toyota/lexus mechanic, I diagnosed it as a bad brake booster, as it showed most of the signs/symptoms of a failing brake booster. Today, I replaced the booster, and the problem still exists.
With the engine running, I can pull the vacuum line off the booster, and there is vacuum there, but noticeably less than that of what a gas engine would provide. I'm looking for a vacuum spec I guess. What kind of vacuum should the vacuum pump pull at idle or slightly above idle?
My new thought is that the vacuum pump is not pulling enough vacuum.
Jay
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When I test the vacuum pump, is it ok to test it up at the vacuum manifold, bu pulling a line off for say, the vacuum ball?
Thanks for all your speedy input.
Jay
FOREIGN GURU
Joined: Jul 2006
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From: Celaya, Gto. MX
17-21 in-Hg is what my book shows = 57-70 kPa
At idle below 10in for more than 7 seconds will illuminate the brake lamp.
Most vac leaks i have found have been at the heat/ac control.
BTW if you sit pumping the breaks you can deplete the vac and set the lamp.
At idle below 10in for more than 7 seconds will illuminate the brake lamp.
Most vac leaks i have found have been at the heat/ac control.
BTW if you sit pumping the breaks you can deplete the vac and set the lamp.
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I have not yet had a chance to get over to their warehouse and test the vacuum. Thank you for the actual spec.
Jay
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FOREIGN GURU
Joined: Jul 2006
Posts: 7,655
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From: Celaya, Gto. MX
That's the problem though, the pedal is rock hard. Its like trying to put your foot through a brick wall. I cant pump the brakes enough to deplete the vacuum and cause the light to illuminate.
I have not yet had a chance to get over to their warehouse and test the vacuum. Thank you for the actual spec.
Jay
I have not yet had a chance to get over to their warehouse and test the vacuum. Thank you for the actual spec.
Jay
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$75 Canadian from a local wreckers. Took them 3 times to pull the right one, but they got it. First one had an 1 5/8" hole for the master cylinder, where I required a 2" hole. The 2nd booster they sent me was a hydro-boost unit....I told them exactly what I required, hole size and all, and they send me a hydro-boost unit.. 3rd and final unit was the correct 2" hole Vacuum assisted brake booster.
Jay
Jay
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From: Ft Scott
That's the way mine was too. I had the hard pedal and the light never came on. And the heater controls worked the way they were supposed to. I thought it was the brake booster but I didn't want to make two trips to the parts store so I bought the booster and pump and rented/borrowed a pulley puller and vacuum gauge. The pump was only pulling 10 inches of vacuum so I replaced it and returned the booster.
Thread Starter
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New User
Joined: Feb 2012
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That's the way mine was too. I had the hard pedal and the light never came on. And the heater controls worked the way they were supposed to. I thought it was the brake booster but I didn't want to make two trips to the parts store so I bought the booster and pump and rented/borrowed a pulley puller and vacuum gauge. The pump was only pulling 10 inches of vacuum so I replaced it and returned the booster.
Jay
