Do hydroboost units go bad? (chevy truck) - Chevelle Tech
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post #1 of 7 (permalink) Old Sep 15th, 09, 9:12 PM Thread Starter
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Do hydroboost units go bad? (chevy truck)

The brakes on my tow vehicle seem weak for what I would expect, 1995 chevy K3500 1 ton pickup with single rear wheels. Hydroboost brakes, and you have to really push hard on the pedal to stop the truck. It is my only hydroboost vehicle I have owned, so I dont know how they should feel, but it doesnt seem right. Do the units go bad? PS seems to be working fine.

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post #2 of 7 (permalink) Old Sep 15th, 09, 10:25 PM
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Re: Do hydroboost units go bad? (chevy truck)

i have owned a few 60's Rivieras and they seemed to eat Hydrovacs.

The symptom of the booster going bad will be a dead brake pedal, like 50times worse than manual brakes. You will still have brakes, just that the pedal will be stiff as hell and almost impossible to get pressed down (both feet for all your worth)
When you pull the line that generates the vacum from the booster it will seem like it has a lot of pressure in it but the booster is no longer working.
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post #3 of 7 (permalink) Old Sep 15th, 09, 11:35 PM Thread Starter
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Re: Do hydroboost units go bad? (chevy truck)

no vacuum, this is hydroboost.

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post #4 of 7 (permalink) Old Sep 16th, 09, 1:38 AM
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Re: Do hydroboost units go bad? (chevy truck)

I had to replace the one on my 99, it was leaking like a sieve... 1/2 gallon pf PS fluid in 440 miles...
But the unit performed ok, check your PS fluid pressure if you can. You can probably do a google search and find out quite a bit more.

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post #5 of 7 (permalink) Old Sep 16th, 09, 2:00 PM
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Re: Do hydroboost units go bad? (chevy truck)

I had to have the hydroboost replaced on my '99 K2500 crewcab several years ago. It was like trying to stop a tank by using "Flintstone" brakes. Luckily it was still under warranty at the time.
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post #6 of 7 (permalink) Old Sep 16th, 09, 2:01 PM
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Re: Do hydroboost units go bad? (chevy truck)

To diagnose; start by pumping the brake pedal a few times with the motor off. While holding the brake pedal down and holding slight pressure on the steering wheel, start the motor. If the brake pedal drops and the steering wheel kicks, you have some power steering pump pressure. Checking the actual amount with a gauge is a good idea to see if the pump is weak.

If that all checks out, a common problem with these units is a blockage of flow somewhere in the lines and hoses. It may take removal of all the lines and hoses to check for proper flow to find the cause. I have also seen o-rings break down and clog the system.

So, it boils down to: Is the pump putting out enough pressure? Is the fluid flowing properly (both on the pressure side and the return side)? If so, then start thinking about replacing the hydro boost unit itself.

There's more that has to do with the interaction between the hydro boost and the power steering gear, but this should point you in the right direction.

I hope this helps.
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post #7 of 7 (permalink) Old Sep 17th, 09, 6:26 PM Thread Starter
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Re: Do hydroboost units go bad? (chevy truck)

Thanks, I will flush some ATF through the system and see if I can clean it out. I may put a vacuum booster on it at this point, price for parts is pretty high compared to vacuum power brakes.

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