sgallaty
Engineer
i'm learning some things that most of you probably already know, but I figured I'd share as I go so y'all can make fun of me or give me advice as you feel so inclined.
93 E350 cargo base, barn door side, standard body (it's in my garage pics)
symptoms were - intermittent hard pedal, interior CC controls slow to respond. Brake pressure light was not lit.
developed new symptom of left front brake overheating.
observations :
jacked up left front tire and removed wheel, wheel spun freely
left front rotor has smearing from what appears to be foreign material of unknown origin - possibly contaminated pads?
dot-3 brake fluid appears dark and slightly cloudy, smells burnt in the reservoir
removed interior climatecontrol vacuum control line from vacuum tree and hooked up vacuum gauge to vacuum tree.
tested FAIL 5inches at idle, 12 at 2500 rpm that drops to 5 immediately at idle.
tested interior CC vacuum line, test INVALID - holds no pressure using handheld vacuum pump tester (test may not be valid as interior might be actuating baffles)
tested FAIL vacuum with booster isolated to vacuum pump, tested fail 5in at idle.
tested PASS vacuum pump, tested at 25in
observed check valve grommet deteriorated
tested FAIL check valve
replaced check valve and grommet
tested FAIL vacuum with booster isolated to vacuum pump, tested fail 5in at idle.
removed check valve
tested PASS vacuum isolated vacuum pump to booster check valve - 25in.
so, have a bad booster.
questions from this -
is the vacuum warning switch supposed to have a pinhole leak? I can see why it would - that would not really affect the vehicle during operation but would turn the brake light on when the engine quits before the driver puts his foot on the brake. The check valve on the vacuum assist will keep that system depressured.
is the booster a pain to remove?
I'm probably going to swap the booster with an OEM booster from my spare vehicle rather than roll the bones on some chinese knockoff replacement. I find I have better luck using salvage parts than the cheap crap at autozone.
93 E350 cargo base, barn door side, standard body (it's in my garage pics)
symptoms were - intermittent hard pedal, interior CC controls slow to respond. Brake pressure light was not lit.
developed new symptom of left front brake overheating.
observations :
jacked up left front tire and removed wheel, wheel spun freely
left front rotor has smearing from what appears to be foreign material of unknown origin - possibly contaminated pads?
dot-3 brake fluid appears dark and slightly cloudy, smells burnt in the reservoir
removed interior climatecontrol vacuum control line from vacuum tree and hooked up vacuum gauge to vacuum tree.
tested FAIL 5inches at idle, 12 at 2500 rpm that drops to 5 immediately at idle.
tested interior CC vacuum line, test INVALID - holds no pressure using handheld vacuum pump tester (test may not be valid as interior might be actuating baffles)
tested FAIL vacuum with booster isolated to vacuum pump, tested fail 5in at idle.
tested PASS vacuum pump, tested at 25in
observed check valve grommet deteriorated
tested FAIL check valve
replaced check valve and grommet
tested FAIL vacuum with booster isolated to vacuum pump, tested fail 5in at idle.
removed check valve
tested PASS vacuum isolated vacuum pump to booster check valve - 25in.
so, have a bad booster.
questions from this -
is the vacuum warning switch supposed to have a pinhole leak? I can see why it would - that would not really affect the vehicle during operation but would turn the brake light on when the engine quits before the driver puts his foot on the brake. The check valve on the vacuum assist will keep that system depressured.
is the booster a pain to remove?
I'm probably going to swap the booster with an OEM booster from my spare vehicle rather than roll the bones on some chinese knockoff replacement. I find I have better luck using salvage parts than the cheap crap at autozone.