Hydro boost leak at Master Cylinder

159 Views 6 Replies 4 Participants Last post by Ericglo, 10 d ago

DENIS S

Discussion Starter · 11 d ago

Tracing down PS Fluid leak on my brother's 98 Astro LS RWD. Everything wet under there, dried everything off and started tracing back the leak. Traced it back to where the Hydro boost pump attaches to the Master Cylinder. The three hoses at the top of the Hydro boost (2 hydraulic hoses, and one return to the PS reservoir) are dry and not leaking. I can feel under the area where the Hydro boost connects to the Master Cylinder, and this is where the leak is coming from. There are no other hoses in the area that are wet.
1) Does this mean the Hydro boost is leaking internally?
2) Do I need to replace the Hydro boost?
3) Is it a difficult job?

Thanks
Currently in Port Angeles, WA
Working on brothers 98 Astro LS RWD. 205k miles

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Mmusicman

· #2 · 11 d ago

It's a common leak... I've had several go bad.
It's actually just a no-pressure drip.. past a bad o-ring seal.
But it makes a mess and requires constant refilling.

They make o-ring seal kits for the hydroboost unit really cheap.
I bought the repair kit years ago but never installed it.

I've replaced the Hydroboost unit (with used one) only to have it start leaking a year later.

Recently I used the Blue Devil Power Steering Stop Leak.. and it fixed my leak.
Sometimes I just prefer to try the lazy solutions... which I've had good luck with.

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DENIS S

Discussion Starter · #3 · 11 d ago

Thanks Musicman. Will try the stop leak.

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ehbrown1

· #4 · 11 d ago

It means that the seal on the output piston of the hydroboost is leaking.
It's not difficult to replace.
But an entire unit rebuilt is $150
Replacing the entire unit is easier then replacing that seal.
Have never used a power steering stop leak, but know of some who have. Usually works.

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Ericglo

· #5 · 10 d ago

Taking the Hydroboost apart isn't that hard. The rebuild kit at Pirate Jack is around $35.

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Mmusicman

· #6 · 10 d ago

The issue is merely one leaking o-ring seal.
(it does not require a complete rebuild)
I think I paid about $20 or so for my kit (that I never used yet.. lol)

If you try the Blue Devil PS Leak Sealer.. be sure to follow directions and not use too much.
There is a chance for damages if overdone.

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Ericglo

· #7 · 10 d ago

Mmusicman said:
The issue is merely one leaking o-ring seal.
(it does not require a complete rebuild)
I think I paid about $20 or so for my kit (that I never used yet.. lol)

If you try the Blue Devil PS Leak Sealer.. be sure to follow directions and not use too much.
There is a chance for damages if overdone.

And to get to that seal one has to take it apart. While it is apart, one might as well replace the other parts. Once I knew what I was doing, it is probably a couple of hours of work.

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