mudgudgeon
Resident galah
You're talking about brake failure vs engine not running and therefore no vacuum assistance to an otherwise working brake system.
Two completely different scenarios.
Off-roading Incident/What Happened??
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You're talking about brake failure vs engine not running and therefore no vacuum assistance to an otherwise working brake system.
Two completely different scenarios.
You will find a rock hard brake pedal with little response all the way down the hill after the truck sits a week. Yes it's doable, so long as you never let the speed get above 10mph or so. Glute-melting brake pedal PLUS judicious, functioning-e-brake-assist is your only hope. Curious if any damage is resulting to the brake booster while attempting such a feat.
mudgudgeon
Resident galah
Should not cause any damage, just requires a lot of effort to control speed.
Good point, in my "what if" scenario I was talking about the engine not running. But, in the OP's scenario, even though his engine stalled, technically speaking he also could have had a brake failure. He did not know for certain at the time that his loss of brakes was due to the stalled engine. It is completely possible although not probable that his brakes had also failed. So would it not be wise advice to always pump your brakes if you unexpectedly lose brakes regardless of the engine status?
Again, I love this discussion and I am not trying to be argumentative. I just want people to be safe and it seems to me that the safe thing to do in any unforeseen loss of brakes would be to
1. Downshift
2. Apply emergency brake
3. Pump brakes to see if the brakes come back.
4. Point and shoot for the safest possible bailout....
5. Hold on tight and pray
Haha, been there done that. I was doing my first set of U joints on a tacoma years ago. I got the first U joint apart on the rear driveshaft and suddenly the truck was rolling away with me under it. Thanks to my Indiana Jones training I moved like Junior and successfully rolled out from under the truck before it rolled over my knees. I was very lucky and nimble and I was able to jump in the truck and stop it before it got across the street and into the neighbors driveway.
mudgudgeon
Resident galah
So, I've had that WTF moment in an old beater work car when a rubber brake line split when pulling up at a red light at an intersection from about 45mph.
I applied the brake as usual, pedal felt normal, then suddenly 'released when the hose split and rapidly sunk to the floor with reduced resistance.
In this instance, I had no option but to pump the pedal.
Pedal felt somewhat normal, but rapidly sunk to the floor again. I had to pump the pedal a few times to stop.
In this case, it wasn't rapid pumping, it was semi-controlled. In saying that, it all happened in a matter of seconds.
I think I also down shifted, but can't remember. I just remember looking for a path out of traffic if needed. I managed to stop without colliding with vehicle in front. But was expecting I would crash into the car ahead of me.
Modern vehicles (since 60's or 70's) use a split circuit master cylinder and brake system meaning the master cylinder has two chambers, one feeding the front brakes, the other feeding the rear brakes.
The master cylinder piston acts on both circuits separately.
In my event, the rear brakes where compromised, but the front were still working.
The failure was immediately apparent at the moment the hose split. But I wasn't sure what had happened until after I got it off the road.
In think the additional pedal effort required to try to stop with only front brakes working pushed fluid past the seals in the master cylinder and the pedal sunk to the floor as a result.
I've also had vehicles stall out unexpectedly, and had to coast off the road. In that scenario, brakes work as normal until vacuum is depleted, then pedal effort required increases dramatically.
As @LandLocked93 suggested, effort required to pull the vehicle up is considerable.
This happened to me in my Isuzu trooper and it was the positive battery cable being a little loose on the starter. It would short under heavy throttle. Took me a while to find the intermittent problem.
@leonard_nemoy - When the engine is not running you have no vacuum assist. The brakes will still work but will take a massive amount of pressure from your foot. Doing this down a long hill could go badly in a hurry. Even with both feet on the brake pedal pushing as hard as you can there's a good chance it won't stop if you pick up enough speed.
@leonard_nemoy - When the engine is not running you have no vacuum assist. The brakes will still work but will take a massive amount of pressure from your foot. Doing this down a long hill could go badly in a hurry. Even with both feet on the brake pedal pushing as hard as you can there's a good chance it won't stop if you pick up enough speed.
^^^^^
Well....not the way you want anyway.
Same thing as my Daughter says (she is an RN that works, ER/Intensive Care and Rapid Response) "All bleeding stops eventually"
I just realized that I don't know how to drive an automatic. I'll never complain about having to get out and lock my hubs again. If the transfercase doesn't shift into low in a 60, you will know before you start as it's in neutral. If it stalls, it still sucks, but not that bad.
SmokingRocks
hopelessly addicted to Cruisers
My cruiser did the same thing on this obstacle, except instead of stalling mine slipped into neutral right at the crest. As soon as it did I stood on the brakes but it still went to the bottom of the obstacle and smacked my rear bumper pretty good. So now when I'm doing an obstacle like that I keep it locked in L. If it starts going backward it's not hard to slap shift into Neutral.
I hate to say it but the guy in the video caused his issue, looked to me like he didn't have a ton of experience on slick rock. He was way too heavy on the gas, bouncing the rig up the obstacle, then when it started bouncing offline he came off the gas hard. The engine went from making power to idle way too quickly and the weight of the vehicle and vector of gravity quickly stalled the engine. You want to avoid hopping your rig on slick rock, it breaks things and tosses you offline.
I hate to say it but the guy in the video caused his issue, looked to me like he didn't have a ton of experience on slick rock. He was way too heavy on the gas, bouncing the rig up the obstacle, then when it started bouncing offline he came off the gas hard. The engine went from making power to idle way too quickly and the weight of the vehicle and vector of gravity quickly stalled the engine. You want to avoid hopping your rig on slick rock, it breaks things and tosses you offline.
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Wow, even with power brakes?
"Pump brakes to see if brakes come back" would leave a driver with a stalled engine worse off than if they simply stayed on the brakes. As was said before, they are 2 completely different scenarios and should be approached differently. I understand what you're saying about not knowing the problem and to have a "go to" method, but A quick look at the tach will let you know weather or not you've stalled.
If you have no vacuum (engine stalled) you basically have 1-2 pumps of boost from what vacuum is on the other side of the booster check valve, with each sucessing pump becoming less and less effective. Much better in this case to slam the brakes once and hold it.
If, on the other hand, you have a brake failure (air in lines, broken line, pad becomes unglued (don't laugh, happened to me),etc), then each successive pump becomes more and more effective as your introducing more brake fluid from the reservoir into the lines.
Unfortunately, a single go-to procedure will do more harm than good depending on the scenario.
Great explanation
If the vacuum check valve is bad you won't have any brake boost with the engine off. If the booster has a leak you also won't have any boost. If the LSPV is out of adjustment or bad leaving the rear brakes with not enough pressure, then the fronts will be doing all the work which is bad when pointed up hill since front brakes don't do much in that scenario. LSPV should be replaced every so often.
SmokingRocks
hopelessly addicted to Cruisers
Yea and I was 2 foot driving/power braking. I was off the brake at the top, all tires were chirping then it popped into neutral (idk if my passenger or I inadvertently tapped the shifter or if it happened on its own), I couldn't have been on the brakes any faster (and I was on them with both feet) yet it still came back down. Luckily it stopped at the bottom of the incline and didn't keep going like it did in the video. But the rear bumper had about a fist-sized dent about 2 inches in it, and it's a 1/4" thick bumper.
It was a learning lesson, keep it locked in L. I've also had instances where I lifted the front tires off the ground on obstacles, that's when it's very important to quickly smack it into neutral.
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SmokingRocks
hopelessly addicted to Cruisers
Also I would advise everyone to just stand on your brakes if this ever happens to you. You most likely Aren’t dealing with brake failure but rather engine stall.
pumping will allow momentum to build which is bad.
pumping is only a good option in complete brake failure or panic stops on ice without abs. I’ll tell you from the experience, when your in a clinch moment like this you will instinctively just stand on the brake with both feet, and that’s exactly what you should do.
pumping will allow momentum to build which is bad.
pumping is only a good option in complete brake failure or panic stops on ice without abs. I’ll tell you from the experience, when your in a clinch moment like this you will instinctively just stand on the brake with both feet, and that’s exactly what you should do.
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Yup, that’s it. Priceless if you are stopped on a steep climb, just set a base amount of throttle and then unlock it once you are up the climb.
Mine isn’t staying locked consistently and I need to dig into that because I rely on it all the time.
