Loss of Brake pressure

STCIllini · May 31, 2021

I have a 2017 Chevy Silverado 1500 Crew. Last weekend while towing my boat, I experienced a loss of brake pressure while backing the boat down the ramp. I was on and off the brake pedal and when I tried to stop, the pedal went all the way to the floor and the brakes did not feel like they were going to hold. I had no issues while towing the boat to or from the ramp. I took the truck into a shop for a brake system inspection and they were unable to recreate the problem and did not locate any problems with my brake system.

Yesterday, I had a four hour drive towing my boat. When I got home, I backed the boat into the driveway and had no issues. While repositioning the boat, I pulled forward and back and was again on and off the brake pedal and again, the pedal went all the way to the floor and I lost brake pressure.

Everything I read suggests the problem is most likely air in the brake lines. I was curious if anyone has had a similar issue and if anyone has any suggestions about what to try to fix the issue.

mjm-1957 · May 31, 2021

We have had two other yukons doing the same thing and both turned out to be bad master cylinders. No external leaks just bypassing internally. I would replace it and go from there.

JimCost2014 · May 31, 2021

This would be my guess.

Listening for a loud ticking sound coming from the from the of the engine, drivers side.

Edited May 31, 2021 by JimCost2014

STCIllini · June 1, 2021

mjm-1957- I'm really hoping there is not a need to replace the master cylinder, but I have considered the possibility

JimCost2014- With more research, I have looked into the problems with the vacuum pump. It seems as likely an explanation as any. I also did some research on the NHTSA site regarding complaints about brakes on Chevy trucks. 2 complaints specifically mentioned backing a boat, either down a ramp or to park it in storage. One of those complaints said Chevy replaced the vacuum pump at Chevy's expense. Hopefully I will have the same luck.