So I need some help with what I think is a hydroboost problem. Let’s call it the tale of the hydroboost.

1. The first new hydroboost was installed a year ago due to the seal on the master cylinder side leaking. This was an Oreilly “reman”
2. 6 months ago, the interior seal was leaking fluid into my truck so it was warrantied out with another oreilly “reman”
3. 2 months ago the hydroboost began to act very odd, it had poor pedal feedback and would apply the brakes when turning at slow speed. Following the troubleshooting guidelines pointed to yet another bad hydroboost cue replacement #4 this time I tried a unit from autozone as oreillys didn’t have any available

The last unit was bled and the whole system was flushed to ensure that no contaminants remained. It worked perfectly for about three weeks. As of two days ago I have some of the same symptoms that the last one had.

Brake application is not smooth, as the truck gets slower I have to reduce pressure on the pedal or it will stop abruptly

The pedal acts like it has a catch when first applied.

At times it will get hard to apply the brakes for no apparent reason, the fluid level is good and there is no whining from the pump.

When braking and turning the brakes will be applied harder when the steering wheel is turned even though the pedal pressure is consistent.

Is this another bad hydroboost?

or am I missing something easy?

If it is bad who the heck would have a good one? It’s easy to change but I am sick and tired of changing it.

Thanks for the help!

 

I noticed something else tonight when I was sitting at a light. With my foot on the brake if I turn the wheel I get pressure pushing back through the brake pedal

 

Are you having any issue with the power steering?
What fluid are you using in the system?
Did you do a full system fluid exchange or just a bleed? A full system fluid exchange should take about 4 quarts of Mercon V.

Also it would be helpful if you were specific about the vehicle year, engine, and transmission setup when discussing issues. We can be more specific on thoughts for assistance. I would suggest a footer signature with the details so it is always there.

 

Thanks for the reply Jimmy, My apologies on forgetting to add the truck info.

2000 7.3 Excursion, 307k

No real power steering issues other than it being harder to turn when some of the braking issues are going on.

it was a full fluid exchange with mercon 5

Sometimes it almost seems like the hydroboost runs out of fluid, IE the pedal will get really hard with no assistance whatsoever.

 

no idea what the issue is but Van is my go to hydroboost guru. if he can resolve it you may as send your Rig to the junk yard.
Vanco Power Brake Supply

 

Thanks pirate4x4, I sent them an email.

 

If it is exasurated when turning I would look for belt slippage or maybe a pump issue if you are absolutely sure the system has no air in it.
Is there any foam present in the power steering reservoir after a drive (keep the engine running during the check). Is the power steering reservoir full?