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7 Series - E38 (1995 - 2001)

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Old 04-16-2013, 09:44 AM
omnibus88 omnibus88 is offline
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Location: Orland Hills, IL
Join Date: Oct 2011
Posts: 27
Mein Auto: 1998 740iL
Issue with brakes

I developed issues with my brakes over last couple months.

When in traffic, front brakes tend to sort of "lock up". They won't disengage. Looks like calipers get stuck to the rotors. I need to give some gas and they let go. Also last night when I was sitting at a drive thru, when i was pushing on a break pedal (car was stationary) I heard squeaking noise coming from the brakes every time i pushed on brake pedal harder.

Pads are good, brake fluid was never replaced, looks like brake lines are cracked.

BTW it's a 98 with 117,000 miles.

Anyone has an idea of where I should start ? Fluid and brake lines will be the first to replace but I was wondering if I need new calipers?
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Old 04-16-2013, 10:27 AM
Moveitsmike Moveitsmike is offline
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Location: Arizona
Join Date: Apr 2013
Posts: 24
Mein Auto: 97' BMW 740il, 06' 330i
if they're not damaged i would say so... take a look and see..
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Old 04-16-2013, 12:14 PM
jitsjaf2009 jitsjaf2009 is offline
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Location: Hemet, Ca
Join Date: Aug 2012
Posts: 513
Mein Auto: 1995 325i Convertible
The calipers may just need some cleaning up and lubrication on the piston. I would also flush out the fluid until you get clear at each bleed valve. Hydraulic fluids tend to 'suck' moisture out of the air....I would look at one of the synthetics when you flush and replace.
Calipers are quite simple devices...unless they are physically damaged they can be cleaned up..worst case new seals...
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Old 07-14-2013, 11:48 PM
Podmore Podmore is offline
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Location: Adelaide South Australia
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Mein Auto: 2001 BMW 735i
If the brake fluid has never been replaced it has quite likely absorbed enough moisture to cause corrosion of the caliper pistons; this causes them to stick in the bores and they will not retract once the brake pressure is released. This corrosion will be on the inside of the piston bore, and will damage the seals and cause fluid to weep around the pistons. However sometimes the part of the piston which sits outside the caliper bore will get gooped up with road grime and weeping fluid and stop the piston from retracting.

If the corrosion gets bad enough you will need to replace the calipers. A scrub out with steel wool and new seals will not solve the problem. However, for a short term fix, remove the calipers, take out the pads, and remove the rubber boot around the piston. Spray the exposed portion of the piston liberally with brake cleaner and try to push the piston all the way back in the bore with a 'G' clamp. Replace the pads and have someone gently push the brake pedal down, while you ensure that the piston does not come out too far (having the pads in place should prevent this). Work the pistons in and out a few times. Replace the rubber boot after cleaning off excess brake cleaner and cleaning up the piston as much as possible.

Having the brakes stuck partially on will lead to premature wear of your brake rotors and pads, and increase fuel consumption. You will notice that the wheels are extremely hot after a run.

BTW if your brake lines are 'cracked', you should see plenty of weeping fluid, which attracts road grime; also pretty soon you won't have any brakes at all!
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