Alex E

Was driving home in the pouring rain today. I parked the car for 15 minutes, the drive there was fine, but after getting back on the road, at first the brakes felt normal, as in the pedal felt firm, but after I completely stopped, the pedal started to sink to the floor and you could feel the brakes weren't going to hold very well. I'd have to get off the brakes and apply them again, pressure came back but just ended up going back to the floor again. To clarify:

1) Coming to a stop: brakes felt fine, normal pedal feel
2) Car comes to complete stop: brake pedal gets soft and goes to the floor
3) Let off brake, gets firm for a second, goes back down

My ABS light was definitely on when this happened (it goes on and off), never had any problems like this before. Anyway, the car did this mushy pedal crap for 3-5 minutes, then it went back to normal.

Should I be worried?

SiR_BW

YES, you should be worried... hell, don't you need to stop?

seriously though, sounds like you have air in the lines, didyou just have your brakes done by chance? could be possible, whoever did them didn't bleed them properly.

Alex E

No, the brakes haven't been touched recently. I've driven the car for about 1,000 miles since early last month and haven't had a problem except the oil light coming on.

SpokaneSpeed

Lol well the oil light is a pretty big issue as well... might wanna look into that - immediately lol.

Definitely should be worried about the brake issue. If you haven't had any brake work done lately, you either have a cracked/damaged line, leaking master cylinder, or leaking wheel cylinder/caliper/valve/etc. Either way, its definitely not driveable until its resolved.



Functional Test

1. With the engine off, press the brake pedal several times to deplete the vacuum reservoir, then firmly press-and-hold the brake pedal for 15 seconds. If the brake pedal sinks, either the MC is internally bypassing, or there is a leak in the brake system. (mc, lines, prop valve, calipers, wheel cylinders, etc)

2. With the brake pedal pressed, start the engine. If the pedal sinks slightly, the vacuum booster is okay. However, if the brake pedal height does not vary, the check valve or booster is faulty.

3. With the engine running, lightly press the brake pedal. If the pedal sinks more than 3/8" (10mm) in three minutes, the master cylinder is faulty. (If the A/C is on, a slight change in the height of the brake pedal is normal.)





Leak Test

1. With the engine running, press-and-hold the brake pedal, then turn the engine off. If the pedal height does not vary while pressed for 30 seconds, the vacuum booster is okay. If the brake pedal rises, the booster is bad.

2. Turn the engine off and wait for about 30 seconds. Press the brake pedal several times using normal pressure. When the brake pedal is first pressed, it should be low, then gradually rise with each consecutive compression. If the position of the pedal does not vary, inspect the booster check valve.

3. Disconnect the vacuum hose (check valve built-in) at the brake booster.

4. Start the engine and let it idle. There should be vacuum available. If there is no vacuum, the check valve is not functioning properly. Replace the vacuum hose, and retest.

5. With the engine running, pinch the vacuum hose between the check valve and the booster.

6. Turn the engine off and wait for about 30 seconds. Press the brake pedal several times using normal pressure. Again, the brake pedal should be low when it's first pressed, gradually rising with

Alex E

Oil light came on, literally headed straight to the nearest dealership for an oil change but they were booked. On the way home from the dealership the light never came on again, but I got the oil changed after that anyway, and it hasn't come on since, don't worry.

Will definitely do the test. I'm thinking the ABS was just messing up really badly. I could stop perfectly fine, but once stopped, the pedal went to the floor. Either that or there's air in the system. If it was leaking I don't think I'd have perfectly functioning brakes one minute, then have that issue, then have perfectly functioning brakes again.

djkurious

I had the same exact issue you are experiencing. Master cylinder was the culprit.

tim73

Oil light has nothign to do with changing oil. It has to do with low oil pressure. 9 times out of 10 it is a faulty sensor, but that 10th time you chance it...

Alex E

I was 150 miles from home with no cell service, there wasn't much I could do except drive it like a baby and pray. Like I said, the light hasn't come on since. Maybe it was just a cheap filter, has a genuine Honda filter now.

I googled my problem and it came up on the NSX forum, most answers pointing toward the master cylinder. Hope it's not too expensive, guess I won't be driving my car until it's fixed.

NerfGunner420

well first of all what are we doing diagnosing other parts. people we had an abs light meaning there is a stored code in the ecu.etc you need to pull that code

Alex E

I know I should get the code. You can stick a paperclip in the connector to get the code, correct?

Another problem could be that the brake fluid is too old (at least 3 years old) and there's air in the system. Regardless, I won't be driving it until it's fixed.

holmesnmanny

air doesnt just appear in the system unless the system is opened ... you either have a leak or a bad master cylinder ... likely a bad master cylinder

76 camaro car

Master cylinders only around $40.

Alex E

Going to have it checked out Wednesday morning at a Japanese/Euro repair shop. He said $50 to inspect it and will call with repairs after. I did do a search and found that a new master cylinder would be very cheap. I'm not sure about bleeding them though, I don't have a lot of experience, nor the space or tools to do it really.

Assuming it does need a new master cylinder along with a flush, do any of you have a recommendation as to the limit of what a shop should charge for that? I didn't even call the Honda dealership, I know they'll charge 2-3x what a good independent shop will charge. The guy on the phone said the MC's rarely fail on these cars but I already had my bet on the MC based on what I've read.

If it's not a hard job to do it all by myself, if it is, it'll head to the shop on Wednesday.

djkurious

Not sure what they charge in your area, but go to repairpal.com and check on labor prices. If anything, I would take the part to the shop with you.

holmesnmanny

$200 - $250 or so including a brake fluid bleed ... should be someone that can do it for $200 .. just use yelp to find good review places and then phone shop it

Alex E

Took the car to the first shop and they charged $50 to look at it. Got a call saying the master cylinder is leaking. To replace that and a brake fluid flush he wants $487 including tax. I called a different shop that's farther away, but he has absolutely glowing reviews and will do it for $412 including tax. More than quoted here but it's the cheapest I've found and the best rated shop pretty much in the state for Japanese brands. Going to pick up the car from the first place and take into the 2nd shop in the morning, although he won't be able to work on it until Friday.

giovannie23

You should first check if you have brake fluid that would make sense

SpokaneSpeed

Ouch!

holmesnmanny

i suppose if you live in an area that doesnt have a lot of mechanics you might have to spend $300 but $400 is really too high imho

its possible to diy you just need a set of flare wrenches .. it should be a 12mm head to disconnect the lines ... then u can get some plastic hose from home depot to use to bleed the lines after

Alex E

Ended up costing $380 with tax, less than he said over the phone. New master cylinder and brake fluid. Now the pedal feels like it did before, a bit soft (to me), good bit of travel pedal, but the brakes work well. Is that just how it's supposed to feel on this car? I'm always surprised how firm the brake pedal is on an Acura MDX that I occasionally drive.

mx80boy

I seem to have a problem of the same account but my left rear caliper will stick and unstick and stick again. I just did the funtional test and 1 and 3 happened. The pedal go to the floor when car is off not fast but it does fall and then when depressed and i start the car the pedal drops way down.