TXE36

I got an opportunity to drive a MB 500 SL on the track yesterday. It was similar to this. I had just been out with a student who put things together well and got the brakes up to temp.

Just afterward, I took a passenger for a ride and going into a turn, I hit the brakes and the pedal was very hard and no braking effort. Immediately thought ice mode and pumped the pedal and got the car slowed down enough to keep it on the pavement. The dash display went red with a clear stop vehicle message so I pulled off and stopped and shut it down. When to restart it and it wouldn't even turn over. Tried a couple of times and it fired, seemed normal. Pulled forward and the STOP message came back saying "BRAKE FAILURE". Pressed on the brake pedal and it went to the floor. Managed to limp it back to the paddock using the e-brake. Brake pedal still had no pressure. I figured I'd ruptured a brake line.

Popped the hood and inspected the wheels and couldn't find anything wrong. Brake fluid looked good and was full. Got in the car and felt for brake pressure and felt a bit and a pump came on under the hood. Was able to see bubbles flowing out a vent in the top of the fluid reservoir. A few minutes later started the car and all was well.

Very weird and disconcerting. I've never seen anything like it. The owner was able to drive it home carefully. I advised him to have the dealer pull the codes and figure out what happened.

-Mike

AudiOn19s

MB braking is all done by wire and hydraulic pressure is delivered via a pump that will eventually fail / time out. Literally at some point you get a message on the dash that you've pushed the brakes too many times and you need to replace the pump.

I really love our E55 but some of the design stuff on there, like this braking system, are really dumb.

I'm guessing the pump freaked out on you in some fashion but who's to say how / why.

dan212

Fabulous car. Brakes up to the task of hauling the car from flat out to a crawl when a truck pulls out on the autobahn.. But the car is too heavy for track use. Not sure how much traction / stability control is in the E55 compared to the 63's, but that stuff really eats up the brakes on the track on top of weight itself. Great car. Love it. its just not mean for the track. Not surprised the brakes overheated.

Texas RS

My wife's SL550 had a brake pump failure inside of 1500miles from new, it has never seen the track and won't ;-). It has been fine since a new pump was installed...

TXE36

So if this car has an electrical failure, no brakes? All this advanced stuff, and the ebrake was a pedal on the left with a old fashioned pull release.

Yet another reason why I consider myself old school.

-Mike

Jabs1542

Thank goodness you had that. The ebrake on my 991 is a button down under the dash just above my left shin, I can't hardly reach it without almost hitting my head on the steering wheel - what were they thinking?