Can someone tell me if compressing the front brake Pistons could have anything to do with a leaking Hydroboost? I completed a changing ball joints and putting new brake pads on yesterday and when I got back from test driving it. Red fluid was spraying out of the top of the unit when the steering wheel was turned. At that point, I turned it off and put my tools up for the day because I was too tired to mess with it. I just thought it was a little too coincidental to do a little brake work and then have that leak happen. I read somewhere the Hydroboost is somehow used with the brakes and steering but I couldn't find a good explanation of it that made sense to a simpleton like myself. Any help would really be appreciated!

 

The hydrobooster diverts power steering fluid when the brake pedal is depressed to hydraulically assist in pushing on the master cylinder. With the brake pedal is in its fully returned position the is a slight gap between the hydroboost pushrod and the master cylinder piston.

Did you have the brake pedal partially applied when doing the work? That is the way we always did brake caliper replacements so brake fluid would not drain out, but in 30 years we never had the problem you describe.

 

Thanks for that explanation Jack! I didn't have the pedal partially pressed. My plan was to do a flush and fill of PS fluid and brake fluid after getting thrall joints in.
Once I removed the caliper and caliper braket, I hung it off the frame with a heavy duty zip tie to keep pressure of the brake line. Once I got the BJs replaced, I just pressed the Pistons in with a clamp and put the pads on.
Do you think what I did caused it to leak out of the hydo boost? I'm about to get out and see exactly where it's coming from, so maybe that info will be more helpful. Thanks for your help.

 

Compressing the calipers, should only push back brake fluid into the reservoir. It shouldn't affect the hyrpdroboost. Is your power steering fluid over flowing at the power steering reservoir, or is it coming out between the master cyclinepder and the booster? You may just wish to flush brake fluid completely and bleed all brake cylinders first, and then see. The power steering fluid level where you left it before you started, if it's low, perhaps there is a leak between master and booster as above. It's also possible a leak elsewhere, so you will have to check thoroughly where the ps fluid is coming from.

 

As Mike just posted, with the m/c at rest any pushed back fluid would go into the reservoir.

 

None came out of the reservoir. It's either coming out of the fitting where thee hose goes into the Hydroboost or the pulley. I took everything out so I could see from above and everything is dry down to the pulley. I did find that the nut on that high pressure hose was a little loose and I tightened it with crows foot but when I started and turned the steering, it squirted out again. Is it common for fluid to come out where the pulley goes in to the Hydroboost?

 

The brake fluid reference was only to say there would be no pressure on the hydroboost from pushing in the caliper piston. I don't think Mike or I was trying to say your fluid is brake fluid.

Now your going to have to explain or show a picture of what you're identifying as a pulley on the hydrobooster.

 

Please pardon my ignorance. I don't know much about it. Is the power steering pump on the front of the engine and the hydro boost mounted up against the fire wall? I think I refered to the power steering pump as the HB. The leak is from either the behind the pulley on the left front lower of the engine or the line that goes in just under that pulley. Sorry for the confusion.

 

That is the power steering pump and compressing the calipers should have no effect on it what so ever. Sounds like Murphy hit you on this one.

 

PS pump X2.

 

he sure did! On top of that, the rubber boot on the front right caliper gave out and I had to replace the caliper. I was hoping it was just the hose going from the Hydroboost to the ps pump but no such luck there. I replaced it and it's still pouring out. Looks like it's behind the pulley on there pump. That Murphy is a real sob! Can I get a pulley puller on it without messing with the fan or radiator?

 

I can say yes ....... but I don't have the shroud. And it still a PITA.

 

I wouldn't expect anything less. Just changing that line was a PITA even with a crows foot. If things don't quit breaking, this truck is gonna prove my wife right. She can't stand it. I'll have to admit, it's getting old laying under it or sitting in the engine bay.
Thanks for your help!

 

I asked my question wrong. I meant t ask if the pump will come out without messing with the fan or radiator?

 

Oh, it's still yes. And it's still yes that I don't have the shroud. What I was trying to say is if you have the shroud on my info might not give you the right answer. If the shroud is in the way and you have to pull it, then the fan needs to come out with it.

Soooo, if you have a shroud grab a bowl of popcorn and we'll both wait for a shroud equipped truck person who changed the pump to give his answer.

Plus the three or four bolt question will probably come up too.