E39 problems

"Decay buys too many beaters" (decay) 11/20/2015 at 00:36 • Filed to: cheap e39, e39 problems

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Brake pedal felt weird (downright scary actually) really hard and a bit crunchy, so I rooted around this evening to see what was going on. Found 4” of water in the compartment containing my brake booster. Who the fuck designed this with such a small drain? Also found this...

I am now truly afraid. Lucas, inventor of the first intermittent wiper and the self dimming headlight has had a hand in making parts for my car. Parts with sensors that have now been submerged in water... Crap.

**UPDATE. Just siphoned over half a liter of water out of my actual brake booster. Found that it was FILLED with water after my first attempt at fixing proved unsuccessful. Also I’m now assuming that water was pulling through the brake booster via the vacuum line and causing my misfire on cylinder 8

StoneCold > Decay buys too many beaters 11/20/2015 at 01:26

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http://oppositelock.kinja.com/unexpected-sup…

#E38Problems as well.

M54B30 > Decay buys too many beaters 11/20/2015 at 02:25

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Funny you mention it, the brakes in my E39 were weird this morning too. No rain like you must have had, but it was our first really cold day. Pedal felt “choppy”... Resistance, then a 0.5” of free play, resistance, another 0.5” of free play, etc.

Cleared itself up after a few hundred feet but weird. It’s never done that before.

RPM esq. > M54B30 11/20/2015 at 02:31

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That almost sounds rotational...like a spot of ice on the rotor interfering once per rotation.

Decay buys too many beaters > M54B30 11/20/2015 at 02:40

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That’s almost exactly how my pedal felt except “choppy” for entire pedal travel and only when stopped. But mine did not go away.

Here’s my thoughts after another hour of troubleshooting. If the level of water ever gets high enough to touch the brake booster water gets in and will stay in. I unclogged my drain and removed all the water but when I took it out for a drive brakes still felt weird. I pulled the vacuum hoses and found that my booster was FILLED with water. I was able to remove at least three quarters of a liter using a siphon pump.

Decay buys too many beaters > StoneCold 11/20/2015 at 02:48

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Heard a fun joke the other day. If Lucas made guns, wars wouldn’t start either.

KatzManDu > Decay buys too many beaters 11/20/2015 at 05:21

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Now I have something to go out and check at work! I just passed my Belgian CT (MOT/APK/Annual Inspection) but they don’t go this deep into things.

M54B30 > Decay buys too many beaters 11/20/2015 at 13:11

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Hmm i might have to poke around a bit. More accurately, mine felt like when you install new pads and it takes a few pumps to get the pads on the rotor surface again. Let me know if you discover anything else

nickneo > Decay buys too many beaters 11/21/2015 at 20:13

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I see flies still like shit.

Decay buys too many beaters > nickneo 11/21/2015 at 22:41

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The repair required a blood sacrifice and I was fresh out of small mammals.

Seat Safety Switch > Decay buys too many beaters 12/08/2015 at 18:10

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I’m a little surprised you managed to get water inside the brake booster. Even submerged, I would have expected that if the seal could keep vacuum in, it could keep water out.

Willing to bet the booster is pooched either way.

There should be a check valve on either the vac line or the booster that keeps the booster from losing vacuum, I would hope that would keep water out of your vacuum source as well.

Note that I’ve never worked on an E39 so I can’t say for sure.

Decay buys too many beaters > Seat Safety Switch 12/08/2015 at 18:46

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That would work, but the check valve allows flow out but not in. so it wouldn’t stop water leaving the booster. Not sure exactly how the water got in, but drained it appears to be working just fine for the time being, I’ll replace on failure.

Seat Safety Switch > Decay buys too many beaters 12/08/2015 at 21:45

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Yeah, I was commenting on the check valve more to dampen your spirits that it was water that was responsible for your #8 misfire.

Do a few static brake booster tests (they’re easy to do in your own driveway or even on your commute) and then if it’s good to go I’d say you’re laughing.