Sin_Chase

Semi brown-pant moment coming into work this morning. A local event has decided to yet again close major roads off during rush hour and cause traffic from hell and my diversion left me sitting in bumper to bumper queues. Part of which was a downhill section.

Rather than burn fuel away I knocked the engine off and allowed gravity to do the work for me, something I have done many times before.

Chillaxing listening to my music and when a space opened up I coasted a bit, applied brakes and waited some more. Rinse repeat a few times. So I am halfway down, coasting again and I come to brake and nothing. Lot's of resistance on the brake pedal but no breaking power being applied. Rather quickly approaching the back end of the car in-front and I am scrambling to the ignition, getting it on and pushing the Start Button like it's my ejection seat handle in a fighter jet that's plummeting to the deck at 500MPH screaming ALTITUDE ALTITUDE in my ear.

Engine fires up, what I assume is the assistance pump(s) kicking in and I get braking power back and stop as fast as I damn can.

What the hell! So, this has never happened to me before, and while I fully understand with no engine running you don't have any pumps running but since when did you NEED the pumps going to apply at least some form of braking power?

I'm no mechanic or engineer in the field otherwise but I have always been under the impression a braking loop will work without ABS pumps or whatever else running? If not, please enlighten me otherwise!

Dixon Motorsports

Brake servo only kicks in when engine is on so it can take vacuum from the servo, so if the engine is off then you have to use your own power to stop the car.

richmc

You would have had fun trying to steer out of the situation also, thats why engine off costing is illigal.

Sin_Chase

Indeed, it's not something I would ever do in normal conditions. But gridlock traffic moving at about 10 metres a minute is not normal circumstances

loftust

I agree with Dixon about the servo...you could have used the handbrake however

Sin_Chase

I was poised but I was somewhat happy that getting the engine re-running would give me back full braking assistance/power. Luckily it did not come to that - just not had the power drop off that rapidly before. The previous brake was as good as normal like the engine was running then the next was like I was pushing against the floor. Unexpected contrast. Lesson learnt though

WinFreak

How much fuel does a car use on idle... Man you must be tight

jsh

When the engine is running it create's a vacuum in the brake servo which help's lesson the pressure needed on the brake pedal .

When the engine is off you still have a vacuum in the servo but each application ofthe brake's lesson's the vacuum so after a couple or three pump's you have no power assistance and need leg muscle's like a sumo wrestler to get the brake's to work .

Regard's John .

RichwiththeS2000

I did the same thing while rolling down the hill in the KFC drive through!

As John says though, if you stamp on it hard enough, they will work but does catch you by suprise!

L0rdMike

I thought I read the S2000 had to have the engine running when moving or you kill the diff?