02 Escalade 6.0 w/ hydro boost problem...

[Amroman]

Ok I'm new here, first post woohoo! I'm a GS tech at Firestone and I don't actually own a Caddy(anymore) but I was tasked with brake inspection and I'm not new to how brakes work.

So basically I got in the truck to pull it into the stall and instantly noticed the pedal went straight to the floor before I started it. To add to that, when it was started, the pedal would pulsate when pressed while parked. I drove it in with no problem braking.

After inspecting everything here is what I found. Pads were fairly new, fluid was crystal clear and rotors were not warped.

I'm a student at UTI also so I'm familiar with base brake theory and operation and in my opinion I'm pretty smart when it comes to common issues. This one has me and the C techs stumped. There were no A techs around to ask for help but in my opinion it sounds like air in the system or something hydroboost related. Since I was in a rush I basically covered my own ass on the ticket and wrote "pedal pulsation, recommend further diagnostics". The guy didn't even state a complaint about the brakes, just that he wanted an inspection before his road trip.

My random guess is that he or a friend did his brakes, saw he was low on fluid, topped it off with new fluid and didn't bleed the system. I'm stumped here and I'll probably never see it again but just wondering if this a common issue or some ideas.

 

[livingez_123]

When did they go to a Hydro boost? everyone I have seen come with a vacuum booster. a hydro boost is mainly used in diesel applications where there is no vacuum source. And if the pedal went to the floor there is a good chance that there is a bunch of air in the system or the master cylinder is bad.

 

[skbishop90]

Hydroboost wouldn't have anything to do with the pedal going to the floor. That would be a base brake system problem. I agree with livingez_123's post on a possible master cylinder problem. If he did his own brakes, they could have opened the bleeder screw to compress the caliper and possibly gotten air in the system. Although I don't know why they would need to open the system, that would allow air in the system for the same problem.

The pulsating pedal. Was this as low speeds? You said you pulled it in the shop and noticed it, correct? If so, it either has air in the power steering system that is messing with the hydroboost, or the hydroboost system has air in it or faulty. Possible ABS problem but Im sure you would have noticed the ABS light on the dash.

 

[Amroman]

No abs light that I can remember and the pulse was only while stopped. One thing I did notice was the power steering fluid's dark murky look. I'm assuming he has probably neglected it since he's owned the vehicle because most people don't ever bother with it until it's a problem.

I'm pretty sure it's hydroboost, the main giveaway was the line going from the power steering pump to the master.

Hopefully this guy comes back and has his stuff fixed because I would really hate my hands to be the last ones that touched his brakes before barrels through a red light with no brakes or somethin.

If the power steering fluid becomes contaminated, could that cause the pulse?

 

[skbishop90]

No abs light that I can remember and the pulse was only while stopped. One thing I did notice was the power steering fluid's dark murky look. I'm assuming he has probably neglected it since he's owned the vehicle because most people don't ever bother with it until it's a problem.

I'm pretty sure it's hydroboost, the main giveaway was the line going from the power steering pump to the master.

Hopefully this guy comes back and has his stuff fixed because I would really hate my hands to be the last ones that touched his brakes before barrels through a red light with no brakes or somethin.

If the power steering fluid becomes contaminated, could that cause the pulse?

That's what Im thinking. The power steering fluid may be dark but it shouldn't be murky. Originally the fluid is a red color. Over time itll get dark but shouldn't be murky. Either water or brake fluid may be leaking into the fluid.