She’s almost at 500K miles and has generally been excellent transportation… but there are a few issues I have yet to resolve.

Now when i replace a part, I generally replace all the associated parts. Replaced HYDROBOOST (which was the problem) but also replaced Master cylinder, power steering pump, fluid reservoir and went to all steel braided lines. New rotors and pads in the rear, up front I got new slotted and grooved rotors, ceramic pads with new calipers. Completely flushed the brake fluid and went to Dot 4 Flushed and replenished the power steering fluid with the same synthetic transmission fluid I use in the transmission (As suggested by a Chevy mechanic).

HYDROBOOST: 2nd one now in less than a year. The first one admittedly was not the Best Quality retailing at $130. The 2nd one however was from Napa Auto parts at $240, not by choice but necessity. The were the only parts store with one in stock and I was supposed to be rolling out in hours.

SO… I transport people all over the US. And after this last Hydroboost replacement I found that if I sat in the van with the AC going some 35-40 minutes or more, when I applied the brake, the peddle would go all the way to the floor!!! The braking was still there with a great amount of effort, but it wasn’t safe need I have to stop immediately.

Upon closer inspection I discovered that the brake fluid reservoir was overflowing due to the expansion of the fluid at near boiling temperatures. The power steering fluid appeared to be boiling itself. After the second occurrence I pulled into a car wash and soaked the Hydroboost down as to cool it off. And the brake pedal resumed normal operation.

I’ve installed an auxiliary fluid cooler for the power steering fluid but still have the brake pedal issue after idling with the AC on for 30-40 minutes or more. Any suggestions???

 

Yes
The power steering takes power steering fluid, not transmission fluid. It says so in the owner's manual.