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#1
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Vacuum pump check valve confusion
Hi all, 1980 300cd with the older style vac pump. My check valve is just a hollow fitting. Pelican parts don't sell this valve but other part stores say valve is same for 1980-on models. I have no vac leaks, holding 22hg, but drops to 0 when brakes depressed. Booster passes all test I know of. Is missing check valve the prob? Should the booster drop vac to zero? Thx for any help
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#2
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The check valve keeps the vacuum from leaking/bleeding off.
The pump pulls the vacuum, the reservoir 'stores' the vacuum and the check valve keeps the vacuum from bleeding off. Very often available at your local PNP locations.
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1985 300D 198K sold 1982 300D 202K 1989 300E 125K 1992 940T "If you dont have time to do it safely, you dont have time to do it" "The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." |
#3
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FYI
Quote:
Are you speaking of the valve in the middle of the thumb size plastic line, going from the vacuum pump to the brake vacuum power booster ??? .
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ASE Master Mechanic asemastermechanic@juno.com Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 1984 190D 2003 Volvo V70 2002 Honda Civic https://www.boldegoist.com/ |
#4
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I'll take some pics. I'm referring to brass valve screwed into vac pump. Plastic inline valve near booster is good.
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#5
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I replaced check valve on vacuum pump, brakes maybe a little better. Vacuum still drops to zero when fully depressed then vacuum builds back up in few seconds. Is this a faulty booster or a vac pump that can't keep up? Any help is greatly appreciated.
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#6
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Answer
Quote:
The brake vacuum power booster is damaged = look for a good used unit.. ************************ If you are lucky, the alternative is a weak/damaged vacuum pump. .
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ASE Master Mechanic asemastermechanic@juno.com Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 1984 190D 2003 Volvo V70 2002 Honda Civic https://www.boldegoist.com/ |
#7
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Thanks, replaced booster. Old one had a litlle brake fluid spray in it. Replaced master too. $49 at jy. Vacuum drops only slightly when braking. No more hard brakes. Beer time
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#8
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Grin
Quote:
.
__________________
ASE Master Mechanic asemastermechanic@juno.com Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 1984 190D 2003 Volvo V70 2002 Honda Civic https://www.boldegoist.com/ |
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