[Sportstick]

Let's put aside efficiency, emissions, and performance just for the sake of the argument. Does anyone disagree that, purely from the point of view of engine wear and tear, a gradual warm up is the best approach, for example, 20-30 seconds of standstill after cold start, and then nothing over ~2500 rpm for first 5-10 minutes (as we are not blessed with a temperature gauge)? My experience is that most physical matter doesn't like to change states quickly (cold to hot, for example).

[Pparana]

Originally Posted by Sportstick

Let's put aside efficiency, emissions, and performance just for the sake of the argument. Does anyone disagree that, purely from the point of view of engine wear and tear, a gradual warm up is the best approach, for example, 20-30 seconds of standstill after cold start, and then nothing over ~2500 rpm for first 5-10 minutes (as we are not blessed with a temperature gauge)? My experience is that most physical matter doesn't like to change states quickly (cold to hot, for example).

There all related, friction is the enemy (wear, performance, fuel consumption), which is the highest when cold. That is why the new engine in the 240, is designed to stay warm for up to 18 hours after shut down.

F1 motors tolerances are so tight they are effectively seized until warm, they heat the fluids prior to start.


low rpm(once started, oil pressure equalized) light load until warmed up.

[moldcad]

On another note: after the above-mentioned software update at my Dealership, the beep I used to hear as confirmation when storing my seat position to one of the 2 memory spaces is now gone I miss it, as it gave me confidence when using while driving that my new seat settings have indeed been memorized. Is it my car, or has anyone else had similar experience after the latest software upgrade? I'm sure it can be repaired by coding, but never have time for that...

Piotr

[moldcad]

So I'm bumping up this old thread of mine, even though another similar one has been active in the meantime... This time, I'm rather seriously worried though

True - my car has spent the winter mostly sitting in the garage. Not because of to much snow, too cold or anything weather-related; I just didn't have to drive but instead was very busy (I'm working from my home office). Some 2 weeks ago I gave my car a good wash, and - after just a short trip - put it to the garage again. Today I started the engine normally, put the car on R, and released the brake pedal...

Nothing. The car was stationary. I stopped the engine and started it again; tried to reverse from the garage: still no move...

I got nervous, as I had a business appointment. Restarted the engine again, and this time not only released the brakes (while in reverse), but also pressed the gas pedal slightly. It felt like the car wanted to move, but was blocked by something... So I decided to press the gas harder - and after a loud "bang", it reversed normally as if nothing was wrong!

No error codes, nothing. Only my rotors look more rusty than ever... Could it be my handbrake getting stuck on the rear rotors?

Scary... What do you think guys?

Piotr

[SteveInfante]

Mine does this from time to time. I can only assume but I'm thinking that the E brake gets seized slightly and needs some encouragement to release. My driveway is sloped a bit so it gets some help from gravity when I'm trying to back out. I have the MT and sometimes when I release the E brake in N the car doesn't move. I can usually rock back and forth in my seat and it will brake free and start rolling back. I wouldn't worry too much about it.

Mostly happens if I wash the car in the driveway and then let it sit for a while, drying the brake dust residue onto the brake pad and rotor.

[moldcad]

Thanks so much Steve (I assume this is your first name? ).

Yes - my only explanation is the hand-brake having seized on the rear wheels. BTW - why do you call it E-brake? I was under impressions we don't have E-brake in our M235i - just a normal, mechanical one (I do have E-brake in my Golf 7 R; not only is it engaged by flipping an electrical switch rather than a pulling the traditional lever up, but it uses the main braking circuit on all 4 wheels as opposed to the classical handbrake operating on the rear only...

Anyway, do you guys see any explanation for the fact which is causing a doubt and serious concern in my mind whether it actually was "just the seized hand-brake": when I tried to rock the car, it seemed to be willing to move forward, but not a millimeter backwards. Cannot state this with absolute certainty, though, as my front tires are stopped by the wooden board I had fixed to my garage's floor so that I'd never touch the front wall with the bumper (my garage is extremely short)... Were it not for the fact that the car wasn't stopped dead in Drive the way it was in Reverse, I'd be 100% sure it was nothing more but the seized handbrake - in my 45 years of motoring, I had many situations like this when during a freezing night, my wet brakes got "welded" so much that I had to use a warm water splash to free them... But at those occasions, the car wouldn't move at all neither forward not backward, so the reason was clear and obvious.

So - considering how the emergency/parking brake operates on rear wheels in the 2 series - can someone explain why, when it's seized like this, it blocks the wheels' reverse movement more than it does their forward rotation? If you help me understand this, I will rest assured there is nothing to worry about (I hope nothing was/is wrong with the AT/torque converter as no error light went up, and there are no warnings in iDrive vehicle status)... Cheers,

Piotr

PS. One other thing (not so much worrying but making me wonder): as I said, my car did have several long periods of not being used at all during this winter (I only use it for long trips, and it so happened I had less than usual need for them lately). The car was sitting in the garage for several days and not always clean between those rare trips, and yet no rust developed on the brake rotors (true - the temperature was well below freezing most of the time). But after the wash, even though the car wasn't used for a much shorter time - I'm having the rotors severely rusted now...

PPS Here is the link to the parking brake parts (inside rear wheels):
http://www.realoem.com/bmw/enUS/show...diagId=34_1972 . As can be seen, this indeed is a very traditional mechanical brake with shoes, acting inside an additional drum; does it explain a possibility of complete seizure of only reversing rotation of the wheels?

[XutvJet]

Not an issue at all. I get this brake "pop" all the time after washing the car and immediately parking it for a day+. The rotors have a lot of iron in them and the rust builds up and binds to the performance brake pads. Breaking of the buildup is what results in the pop you hear. The issue isn't with the ebrake as it's located inside the rotor hub. No water is getting there.

[moldcad]

OK, thanks BTW - as you're also using the "e-brake" monicker - I guess you mean "emergency brake"' and not "electrically activated brake" as I first thought, is that correct?

Piotr

PS. If it was just "a pop" as you describe it, I wouldn't be alarmed at all; in my case to break the corrosion build-up, quite a lot of engine power was required and the sound was loud and hard. Scary, I'd say - nothing like I heard many times with other cars before! Perhaps it's the matter of the "performance" brake pads' material?

[morphomeman]

Lesson learned: do not engage the emergency brake when parked on a flat surface for a long time. I stored an old VW bug for a few months some years ago and had the devil of a time getting the brakes to unfreeze. Drums, too!
As for E-brake, these guys are just talking fancy. I have never heard or seen this word in my very long life.

[moldcad]

But in a post before yours, it's been stated it isn't the parking brake's shoes inside the rotor hub, but the rotors binding with the main brake pads with rust... Also, even the manual (not to mention my experience with previous cars using this kind of parking brake) suggest one should use the parking brake as often as possible, or the linkage and all other moving parts will corrode, get dirt etc. resulting in the whole mechanism losing effectiveness... And when are we supposed to use the parking brake "often", if not during actually parking the car? Plus, how often do we park it on a sloppy surface?

Considering all the above, I guess I've developed a habit (almost a unconditioned reflex) to engage parking brake when storing the car in my garage...

On another note: the rotors are so badly rusted after I stored my M235i for several days after washing it that I wonder whether they gonna shine again just after normal brake usage over several hundred kilometers, or if I should disassemble, clean and perhaps even grind/polish them...

[morphomeman]

I never suggested not using the hand brake, only that it is bad to leave it on for an extended period (days, weeks), especially in cold damp weather.
And yes, if you don't use it, it will corrode.
What you need to do is get out of the habit of using it under these particular circumstances, when it is not needed anyway.

[moldcad]

So, probably all of us witnessed BMW's rotors rusting after a couple of days not driving it and storing in a humid place, or in the rain. All this have never posed a problem to me, as it's always been enough to drive (and brake) the car normally for a couple of kms.... Not this time, though - just look at how my rotors corroded: the surface that the pads act upon is already almost clean, but I can't see how the rest of it (particularly at the outside rotor's perimeter) can possible get clean all by itself!!!

As my standard warranty expires in a month time, please advise whether I should push my dealer to - what? Replace the rotors? I somehow don't believe they'd do it; today had my oil service done and when I showed them my rotors, they asked "what kind of stuff I applied when washing the car lately"?

Opinions, please

Piotr

PS. Speaking of rust: the other picture shows my M-package black tailpipes after just 2 years and 25k km...

[ianp622]

Originally Posted by Sportstick

Let's put aside efficiency, emissions, and performance just for the sake of the argument. Does anyone disagree that, purely from the point of view of engine wear and tear, a gradual warm up is the best approach, for example, 20-30 seconds of standstill after cold start, and then nothing over ~2500 rpm for first 5-10 minutes (as we are not blessed with a temperature gauge)? My experience is that most physical matter doesn't like to change states quickly (cold to hot, for example).

No, I don't agree. Why would the engine care if it's at 2000 rpm standing still or driving, it looks the same to it. And you're probably not going to be fully burning the fuel if you're not going a little bit above that. Plus, the exhaust gases aren't going to be hot enough to warm up the cats. The whole "let it idle for 30 seconds" comes back from non-synthetic oils, where the viscosity wasn't right for the engine at cold temperatures. Now oils are engineered to work fine throughout a cold start temperature range.