M135i Brake Issue
Discussion
Posted on BabyBMW too, but I thought I'd summarise on here too, just for knowledge sharing really.
My M135i has developed an issue whereby the car hits the brakes quite firmly when on wet dual carriageways. It appears to be the wet weather disc wipe system that is supposed to unnoticeably clear any rainwater off the discs in readiness for the next brake application. However, it just gives them a good stomp instead. If I fight it and jam the throttle to the floor then the engine labours against the brakes and just holds speed. If I lift off, the car will rapidly lose 15mph before it releases the brakes. If on cruise control (yes, it does it there too), it will lose around 3mph and then return to cruise speed, but you feel the initial jerk of the brakes being applied.
Separate from this, the brakes also seem to hold on after a heavy braking situation which is more noticeable when they're hot.
I miss the good old days when BMW brakes would groan and shudder after hard use. I much preferred that to brakes that work all by themselves!
The car goes back to BMW today for them to investigate.
My M135i has developed an issue whereby the car hits the brakes quite firmly when on wet dual carriageways. It appears to be the wet weather disc wipe system that is supposed to unnoticeably clear any rainwater off the discs in readiness for the next brake application. However, it just gives them a good stomp instead. If I fight it and jam the throttle to the floor then the engine labours against the brakes and just holds speed. If I lift off, the car will rapidly lose 15mph before it releases the brakes. If on cruise control (yes, it does it there too), it will lose around 3mph and then return to cruise speed, but you feel the initial jerk of the brakes being applied.
Separate from this, the brakes also seem to hold on after a heavy braking situation which is more noticeable when they're hot.
I miss the good old days when BMW brakes would groan and shudder after hard use. I much preferred that to brakes that work all by themselves!
The car goes back to BMW today for them to investigate.
I didn't think that the m135 had the brake drying function. Reason I say that is that on my way back from Le Mans this year weather was awful and I had a significant delay in pressing the brake and actually slowing down. I had to actually anticipate as much as I could the slowing traffic ahead.
Mine is a 64 Pre Lci, perhaps the LCI was given this function?
I recall in my '05 E61 and '11 E92 you could feel a pulsing through the brake pedal when the windscreen wipers were on which I always thought was the brake pulsing against the disc - never had an issue in them.
Mine is a 64 Pre Lci, perhaps the LCI was given this function?
I recall in my '05 E61 and '11 E92 you could feel a pulsing through the brake pedal when the windscreen wipers were on which I always thought was the brake pulsing against the disc - never had an issue in them.
Mine is a 64 plate too. I thought all BMWs across the range now had the brake drying function in the same way that DSC is now present on all of their cars. I think it is supposed to be imperceptible in use too.
Either way, the Mini that they've given me in the meantime exhibits perfect braking which does reassure me that I'm right in saying that something is seriously wrong with my M135i brakes.
Either way, the Mini that they've given me in the meantime exhibits perfect braking which does reassure me that I'm right in saying that something is seriously wrong with my M135i brakes.
Just got the word back from BMW...
Water has got into the brake fluid reservoir and somehow broken the DSC hydro unit. They will replace it with a new one being sent from Germany. The part (from what I've Googled) is £1940. Fortunately, it's all under warranty.
So if you've got a 2014 M135i and not checked to see if yours is affected by the "quality enhancement" that stops water getting into the brake fluid reservoir then I'd recommend you check with BMW.
Water has got into the brake fluid reservoir and somehow broken the DSC hydro unit. They will replace it with a new one being sent from Germany. The part (from what I've Googled) is £1940. Fortunately, it's all under warranty.
So if you've got a 2014 M135i and not checked to see if yours is affected by the "quality enhancement" that stops water getting into the brake fluid reservoir then I'd recommend you check with BMW.
When mine recently went in for a service they replaced the brake fluid resovoir cap as well as the scuttle panel on that side.
Apparently in rare cases the brake fluid absorbs moisture and this clearly causes issues like you have experienced.
When I asked about the work the service guy didn't tell me a great deal - probably because he didn't know - but they dip test the fluid to check for moisture levels. If it's at a certain levels they replace the unit as you describe.
You're one of the unlucky ones I guess but at least you have warranty.
Apparently in rare cases the brake fluid absorbs moisture and this clearly causes issues like you have experienced.
When I asked about the work the service guy didn't tell me a great deal - probably because he didn't know - but they dip test the fluid to check for moisture levels. If it's at a certain levels they replace the unit as you describe.
You're one of the unlucky ones I guess but at least you have warranty.
It seems strange to me that they'd risk not doing a recall on this. The parts they change to avoid the issue must cost peanuts compared to flushing the fluid and replacing the DSC unit under warranty. I guess for some people it will just fail outside of warranty though. That really will be painful.
bennyboysvuk said:
It seems strange to me that they'd risk not doing a recall on this. The parts they change to avoid the issue must cost peanuts compared to flushing the fluid and replacing the DSC unit under warranty. I guess for some people it will just fail outside of warranty though. That really will be painful.
I believe there is a service campaign for this, warranty or notGassing Station | BMW General | Top of Page | What's New | My Stuff