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Brake pedal to the floor!

Dhalsim

Dhalsim

Legendary Member
Joined
27 October 2006
Messages
4,877
Location
Nor-Cal
The other day I was driving in stop and go traffic and I suddenly noticed my brakes felt a little squishy but since I wasn't havening to brake hard in traffic I wasnt sure so then I braked again but this time I figured I woudl just keep pushing on the pedal and see what happens.......well the pedal went all the way to the floor.

Now I was pretty worried but I kept driving cause it seemed if I just pumped the brakes a little the braking power would come back. Anyway I drove the rest of the way home liek this leaving a big gap between me and the driver in front of me.

I checkd under the hood and all the reservoirs are full and nothing is leaking.....

Could this be a bad master cylinder? Where and what else should I check?
 
Yes. I have replaced mine recently.

Dhalsim said:
The other day I was driving in stop and go traffic and I suddenly noticed my brakes felt a little squishy but since I wasn't havening to brake hard in traffic I wasnt sure so then I braked again but this time I figured I woudl just keep pushing on the pedal and see what happens.......well the pedal went all the way to the floor.

Now I was pretty worried but I kept driving cause it seemed if I just pumped the brakes a little the braking power would come back. Anyway I drove the rest of the way home liek this leaving a big gap between me and the driver in front of me.

I checkd under the hood and all the reservoirs are full and nothing is leaking.....

Could this be a bad master cylinder? Where and what else should I check?
Click to expand...
 
Possibly the brake master cylinder is going on you. Also there could be a little bit of air in one of your lines that is compressing hence letting the brake pedal go to the floor. Depending on the age and usage of your car the brake lines to the calipers could be worn out as well. The rubber then expands as you push harder and this causes your brake pedal to feel squishy but you lose no braking performance at all. Stainless steel lines are a fix for the OEM brake lines, bleeding the system again (regardless of how much fluid is the reservoir) is a fix for the air and you're sol for the booster if it's that.
 
OK.....so I should bleed the lines and check again? Is there a way to test if the MC is bad?
 
Most likely master.

As I'm one of the promotors of replacing a car's coolant hoses after 10+ years what about changing the even more important brake lines after 15 years? They're cheap and that's nothing in comparison to...

I don't know about the master cylinder replacement actually. It doesn't cost a fortune either. Mine is on order. :wink:
 
OK....a little follow up............

Went out to the car this morning and proceeded to do the checks as per the service manual. Strangely when I pushed on the pedal with the engine off it didnt go to the floor like it did last night. Anyway I went through all the checks and everything passed as if nothing was wrong. So I went and got some Super Blue and bled the brakes. The fluid looked pretty old and God knows when the PO had it changed previously..........but anyway after bleeding the brakes I took it for a test spin and tried the brakes repeatedly at different speeds and everything is good.

I guess problem resolved for now. :biggrin:
 
I would like to revive this thread because im having a similar issue after having most of my brake parts replaced. Heres the story;
My brakes were working fine but my rotors were rusty looking and the pads were getting low in front. I decided to go ahead and redo then since my car was down for paint. I bought new cross drilled zinc coated rotors, ss brake lines from SOS and had SOS also rebuild and powder coat my calipers, i had the shop install all of this as well as new oem pads and motul rbf600 brake fluid.

When i got the car back the front passenger brake line was leaking and the pedal was sinking to the floor upon steady pressure. I took it to a different shop and they tightened up the leaky brake line and bled the system. On the ride home the pedal went to the floor again.

I then took the car back to the original shop and they said that the metal washers on the ss lines had a notch on them and the calipers were flat and that was causing the brake lines to leak. They replaced the notched or bend washer with flat ones and said the problem should be fixed. I pick up my car late yesturday (at closing time) and drive it home and the first light i come to the brake pedal sinks to the floor again.

If i leave the pedal on the floor with pressure it seems like the car is still slightly rolling and not stopped when on a hill. If i take my foot off the pedal the pressure lifts it back all the way up again but the weight of my foot sinks it back to the floor again. Also on long stops i have to pump the brakes to keep them from sinking to the floor.

What do you guys think? Are the brakes still probably leaking some how (even though ive seen no evidence of this yet) or is there a bunch of air in the lines? Or did something the shop did cause my master cylinder to suddenly go bad on me? I'd really appreciate you guys help here as i have not been able to find a shop i can trust around me yet.
 
Hard to tell over the internet. Please get your car to a mechanic who is capable to work on the brakes.

Hint: If your pedal goes to the floor several times and you don't see the slighest leak: master cylinder. A good mechanic should check for ANY leaks first.

good luck!
 
goldNSX said:
Hard to tell over the internet. Please get your car to a mechanic who is capable to work on the brakes.

Hint: If your pedal goes to the floor several times and you don't see the slighest leak: master cylinder. A good mechanic should check for ANY leaks first.

good luck!
Click to expand...

Thanks, I just put a post in the South Central section looking for a mechanic who has NSX knowledge in my area. I thought at first that it must have been air in the lines or a leak and that any decent mechanic should be able to fix this but after trying two different ones and still having this problem i am ready to take it anywhere that i know will get it fixed right this time. Now i just need to find out where that might be?
 
As previously mention the symptoms sound like a bad master cylinder and sometimes you don't see a leak. Sometimes the brake fluild passes around the piston because the seal is no longer good. The MC is inexpensive and it's an easy DIY. Save yourself the aggrevation of going to another mechanic.
 
GreyHoundSteve said:
Now i just need to find out where that might be?
Click to expand...

Any good mechanic should be able to work on a brake system of the NSX as it's not different from other system except for the ALB. The shop you've been is doubtful because they gave you the car without post-inspection of the work on the brakes which is a MUST. A good mechanic would test the brakes and find the leaking hose/line in under 5 minutes.

If you don't know how to work on the brakes please get your car to a good mechanic. Don't drive it, there's something seriously wrong with your brakes.

Hint 2: If you're loosing fluid this may can be seen in the reservoir. Air makes your brake pedal may feel mushy but not sinking over let's say 20 seconds. You have leak somewhere, master cylinder or any other joint.
 
goldNSX said:
Any good mechanic should be able to work on a brake system of the NSX as it's not different from other system except for the ALB. The shop you've been is doubtful because they gave you the car without post-inspection of the work on the brakes which is a MUST. A good mechanic would test the brakes and find the leaking hose/line in under 5 minutes.

If you don't know how to work on the brakes please get your car to a good mechanic. Don't drive it, there's something seriously wrong with your brakes.

Hint 2: If you're loosing fluid this may can be seen in the reservoir. Air makes your brake pedal may feel mushy but not sinking over let's say 20 seconds. You have leak somewhere, master cylinder or any other joint.
Click to expand...

Don't worry, it will stay parked until i locate a good NSX mechanic. I am sure it is a leak somewhere since all of this started immediately after i had brake work done and i have spotted at least one of the leaks on my own.

I guess the thing that upsets me is that Mechanic #1 left the brakes leaking badly (puddle in my garage), mechanic #2 supposedly fixed the leak yet i didnt make it home before the brakes got mushy again. So i go back to mechanic #1 again because i spent allot of money there the first time and he said he would fix it right this time for me and i leave with the same problem i brought it in with.

This time Mechanic #1 swore to me that they found the problem (which they said was a strangely shaped crush washer on the ss lines they installed) they supposedly replaced all the washers with correct fitting ones yet the problem still persists.

When i did a search most people find that the master cylinder is the problem but i just find that hard to believe when 2 mechanics have both struggled to bleed the brakes and tighten the lines properly.

I guess i'll let mechanic #3 start from scratch and hopefully figure out and fix the problem. I am having other mechanic problems too so i just need to find someone who knows the NSX real well to go through the car this time.
 
Sorry to hear your nightmare with the mechanics. Some time ago I've decided to DIY because of similar nightmares. But I personally don't recommend to work on the brakes of any car if I don't know the facilities and skills of someone.

I hope for you and your car that you find a good mechanic. :)

In general: If your pedal goes to the floor it's either a leak or the master. A defective master doesn't have to leak. You can a DIY test with the car standing but the engine running and step 10 times on the pedal until it goes to the floor, then watch out for puddles on the floor and somewhere else (rims). As you've gone to the synthetic motul rbf600 brake fluid your old master may didn't like it. :wink:

Good luck!
 
Last edited:
In my case the brakes pedal started going to the floor again so I replaced the brake master cylinder and everything is good again. Its a very easy DIY and should only take you 30 minutes to switch out and then maybe another 30 to bleed the brakes.
 

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