by Bitsamissing on Mon Oct 08, 2018 8:20 am
I am not a mechanic... so this is just a mental exercise on my part...
A firm pedal and difficult braking indicate a loss of power assistance. Power assistance comes from the reservoir of stored vacuum in your brake booster, and the vacuum is generated by the vacuum pump on the engine.
Vacuum is stored in the booster to ensure there is at least one good power-assisted stop available following an engine failure.
If say there was something affecting your vacuum pump or the hose to the booster during the long steep climb, you should still have had enough stored vacuum to provide assistance when you hit the brakes near the top. That makes me wonder if there was something allowing the stored vacuum (in the booster) to deplenish (an air leak) during the climb. I can't suggest what that may be though...
It may be an interesting exercise to pay attention to how long your stored vacuum lasts during ordinary usage. Normally if you leave your vehicle sitting for a couple of days, if you come back to it and put your foot on the brake before starting it, the pedal will be very firm because the stored vacuum has dissipated. Leave your foot on the brake when you start it and the pedal will drop down under your foot as the power assistance kicks in. If you leave the car sitting for only half an hour however, when you come back to it the brake pedal should feel like it normally does when driving. If it doesn't, that may indicate an air leak in the booster... an air leak that may get worse under certain conditions... like a steep climb up a sand dune...
Chris
MQ Club Cab Ute