Brake pedal stiff before starting engine

[Yeobh]

The cause of stiff brake pedal is due to NO negative pressure (no vacuum) on the other side of the booster diaphragm when the engine is not running.

The brake pedal is connected to a diaphragm inside the brake booster which helps to reduce brake pedal force only when there is vacuum acting on one side of the diaphragm. This will happen only when the engine is running resulting in a vacuum being created.

[Zack2222]

So what is likely to be faulty to cause loss of vacuum?

Edited September 26, 2024 by Zack2222

[Zack2222]

On 9/25/2024 at 5:06 PM, Jamesc said:

Time to change car.

On 9/26/2024 at 12:55 PM, Zack2222 said:

@Jamesc I am thinking to renew 5 year COE

 

[Stratovarius]

On 9/25/2024 at 4:42 PM, Zack2222 said:

Hi, my brake pedal feel stiff before starting engine so when i press the start button, the car does not sense the pedal is depressed. If i step harder, the car can start. Anyone encounter this problem before. My car is a BMW X1 F48 2017.

Brake booster issue. Bring back pml or workshop to check. 

[ER-3682]

On 9/26/2024 at 12:58 PM, Zack2222 said:

 

BMW X1,"Endless Money $$$ Pit",not i say one..

[Yeobh]

When engine if off, the vacuum assist booster may not have the max vacuum of 27” of Mercury. When the engine is running the vacuum should ideally be at its max.

When the engine is running and if the pedal is stiff, chances there is a leak in the vacuum hose from engine to booster or the engine condition is far from good. That means the engine condition needs further compression or leak down tester to determine the source of fault.

To check the integrity of the vacuum system, the mechanic needs to use a vacuum hand operated pump to stimulate the negative pressure (vacuum). If the vacuum reading drop and does not hold, chances there is a leak in the connections, or the hose condition is questionable. Worst case, the booster needs further inspection.

[Spidey10]

Mine happen for a day or two, took it back and they couldn't replicate the issue and asked me to monitor....press press, can hear the "hush" "hush" but the brakes were still working normally....kept there overnight, they tested the next morning, seems to be ok, so asked me to monitor.....till now after 8 yrs and 8 mths....working fine(touch wood)....

This BM brake pump not cheap...Original will cost an arm and a leg...

[Spidey10]

On 9/26/2024 at 4:15 PM, ER-3682 said:

BMW X1,"Endless Money $$$ Pit",not i say one..

Not so bad lah....the 1st 5 yrs all covered.....after that, need to do periodic maintenance lah....ownself know what need to change and not wait until the parts really breakdown....

dun tell me u dun see leaking coolant after 200k km also dun change meh....i would change already...

[Jamesc]

On 9/26/2024 at 12:58 PM, Zack2222 said:

@Jamesc I am thinking to renew 5 year COE

Got people in MCF renew 5 years and then regret because they cannot renew again.

Come here and complain and appeal to LTA and maybe write to transport minister and still no use.

Consider carefully because renew 5 years can never renew again.

[Spidey10]

On 9/26/2024 at 8:45 PM, Jamesc said:

Got people in MCF renew 5 years and then regret because they cannot renew again.

Come here and complain and appeal to LTA and maybe write to transport minister and still no use.

Consider carefully because renew 5 years can never renew again.

best go for 10 right....got 1 yr and 3 mths to think...

[Achtung]

On 9/26/2024 at 9:41 AM, Jamesc said:

It's just ageing.

What can you do?

Every morning I wake up

I also feel stiff all over.

As long as morning hard, u are A-OK