Very stiff brake pedal

Dmflash

Original poster
Member
Dec 16, 2021
22
Canada
Yesterday leaving work pulling out of my parking spot my brake pedal was so stiff I couldn't press it down. I shut it off and restarted the engine and the brake worked again .I couldn't hear any hissing from the brake booster , any ideas what would've caused this?
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,045
Brighton, CO
The one way check valve at the brake booster may have gotten stuck. They are pretty easy to replace, and cheap.
 
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TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,045
Brighton, CO
No way really to tell that I know of.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Deplete the reserve vacuum in it by pushing the pedal several times without it running and see if it's the same stiff feeling. Start it and see if it recovers. Check the hose to be sure it's not leaking or split. Pull it off the booster and see if it gets good vacuum (engine might stall). I'd also pull it off the intake manifold and inspect it thoroughly. Put it all back together, check for leaks (use the carb cleaner method), keep driving it and monitor for a repeat. If it happens again, I'd replace the booster.

I'd replace the check valve before condemming the booster first. Cheap part and easy to replace prior to replacing the booster.
 

Dmflash

Original poster
Member
Dec 16, 2021
22
Canada
Deplete the reserve vacuum in it by pushing the pedal several times without it running and see if it's the same stiff feeling. Start it and see if it recovers. Check the hose to be sure it's not leaking or split. Pull it off the booster and see if it gets good vacuum (engine might stall). I'd also pull it off the intake manifold and inspect it thoroughly. Put it all back together, check for leaks (use the carb cleaner method), keep driving it and monitor for a repeat. If it happens again, I'd replace the booster.

I'd replace the check valve before condemming the booster first. Cheap part and easy to replace prior to replacing the booster.
I installed a new check valve this weekend, only $30 from Amazon so I figured why not. I also cleaned the throttle body and under the plastic cover was loaded with maple keys , I guess a mouse was making a nest in there. So far breaks are working as should . Hopefully a booster or master cylinder won't be needed . Not sure if relevant but the problem with the breaks only happened once and it was after using the AC for the first time this year, guessing just a coincidence.
 

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