Spongy Brake Pedal or Just Vacuum Assist?

[Brad Steinagel]

Hello forum members,
I have a 2018 Honda CR-V that was due for a brake fluid flush which I performed last weekend. After the flush the brake pedal feels a tad soft. It will go down to the floor if I push reasonably hard on it. However, the brakes work fine. The feels safe to drive and the ABS activates when needed. It’s just that the pedal doesn’t quite feel as hard as it did before the flush, at least from what I can recall. It just feels “airy”. The brakes are responsive to pedal input though. No lag, no fade or anything like that. I came up with a way to test this but I’m not sure if my logic is sound:

The pedal is rock hard without any boost so I’m wondering if what I’m feeling is just the brake booster assist? If I remove the brake booster from the equation by disconnecting it and the pedal firms up that means there’s no air in the system. If after disconnecting the brake booster the pedal still feels spongy this means there’s air in the system and it needs to be removed. Is my logic correct? Is it normal for slight variations in pedal feel to exist after a brake flush?

I should add that I’ve put two quarts of brake fluid through the system so far. All four brake lines were bled using the classic two-person method of pushing the pedal down while cracking the bleeders. The reservoir was topped off after every fourth or fifth pedal push.

Thanks
Brad

• This topic was modified 3 years, 10 months ago by Brad Steinagel. Reason: Added additional info

Topic

[Richard Kirshy]

https://www.youtube.com/results?search_query=test+for+soft+brake+pedal

[Brad Steinagel]

Thank you, Richard, for the YouTube links. I had done a YouTube search prior to posting my question but I still wasn’t coming away with any answers. I did flush some more fluid out of the brake lines yesterday. I had someone else assisting me last time so I didn’t get an opportunity to feel how the pedal was operating. After pumping the pedal myself I’m realizing that what I was feeling was a product of the electric brake booster. Seems some boosters can create a “divorced” feeling from the hydraulics of the system. The vehicle stops fine and is otherwise acting normal. I’m gonna call this problem solved.

[Author]

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