2018 Roadster Rear brake issues

[Robert]

I have a Roadster with low mileage, I just went on a trip and I went to hit the rear brake and the pedal went to the floor. A few pumps and it works great for awhile and it happens again. A few pumps and it’s fine for awhile. Any thoughts?

 

[CrzystghndKC]

I have a Roadster with low mileage, I just went on a trip and I went to hit the rear brake and the pedal went to the floor. A few pumps and it works great for awhile and it happens again. A few pumps and it’s fine for awhile. Any thoughts?

What's the brake fluid level indicator say? Plenty of fluid go to step 2.

 

[Sparky59]

You brake fluid is FULL of water...if the fluid was never changed that is a common trouble....

 

[Robert]

You brake fluid is FULL of water...if the fluid was never changed that is a common trouble....

It’s my second Roadster and I just bought it from a guy that never used it. It had 1400 miles on it. I keep thinking I should change the fluid but didn’t. I’ll get it changed. Thanks

 

[atomsplitter]

While you're at it, check the brake line hose. If it feels soft replaced with braided stainless hose. Old hose will expand reducing hydraulic force on the pistons.

 

[Journeyman]

If the brake fluid doesn't do it with a good bleed, your master cylinder might need a rebuild. Just to include the third variable- fluid, hose, MC

 

[Robert]

If the brake fluid doesn't do it with a good bleed, your master cylinder might need a rebuild. Just to include the third variable- fluid, hose, MC

Yes, I agree.