Brakes dont work on highway

[yegor biryukov]

To preface this, I will say that I have watched most of eric the car guy’s videos, browsed through the forum a bit, and have also taken the car to the dealership for this issue, which remains unsolved.

2003 nissan maxima
~140000 miles

The problem that occurs is that when I’m on the highway, after a little while the brake pedal doesnt work. For example, after driving on the highway for at least 10 minutes, when I go to get off on an exit, I press the brake and it sinks all the way to the floor and doesnt stop the car. I then have to pump the brake up and down around 3-4 times for it to stop the car like it normally should. This problem only shows up when I drive on the highway, either because of highway speeds (65+), or because I havent used my brakes in a while (because im on the highway!). The brake works PERFECTLY fine if i am just driving around the neighborhood or even on fast roads (55mph) that do have traffic lights. But after about 5ish miles of highway driving, the problem shows up and persists until im done driving for that period of time.

I took the car to the dealership and they replaced the rotors and brake pads, and upon my insistence also changed the brake fluid, and the problem still happens. I took it back there to tell them that they didnt fix anything, and this time they said they were “90% sure” its the master cylinder, and they want another $300 from me for them to take a shot in the dark and fix that. The mechanic who worked on the car insisted that he checked for leaks, that he did change the fluids the first time, and that if it was a caliper issue he would notice a smell.

My thoughts are that either
1. it is the master cylinder, and for some reason they missed this problem the first time because they couldnt replicate my problem because they only took the car around local roads. (they didnt tell me theyd try to replicate the problem or else i would have INSISTED they take it on highway, even though the invoice i gave them says that i stated that the problem only shows up on the highway)
2. they didnt actually change the fluid the first time, and there is either a leak or some air trapped in the fluid.

Please let me know what you guys think. I dont want to give them another $300 of my money just so they can take another shot in the dark.

Topic

[Its me]

Have you had any exhaust work done on this car which coincided with the brake issue? The reason I ask, is that there are very rare occurrences of the exhaust piping when replaced coming too close to a brake line, which causes the fluid to heat up, thus losing its ability to provide proper pressure…. It manifests when heated up and will go away and it cools off.

Probably a long shot, but it has happened in rare circumstances.

-Karl

[yegor biryukov]

interesting that you mention an exhaust issue. The back end of my exhaust pipe is corroded into 3 pieces. The piece that connects to the engine, the piece with the muffler, and the piece that the exhaust gas exits through are all so rusted that they arent attached to each other any more.

do you think this could be my issue?

[Its me]

That is extremely suspect… Get that repaired and see what happens…and please keep us posted 🙂

-Karl

[yegor biryukov]

I was going to let that exhaust thing go because im lazy, but now this gives me extra incentive to get it repaired. I will definitely get it repaired (hopefully soon!), and I will keep you updated.

Thanks for the quick reply, and thank you for saying something that actually makes sense!!!

[Ben]

i had the same problem a few yrs ago, it was the seal in the master cylinder had worn and was allowing the fluid pass the plunger

[Author]

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