hydro boost leaking

[HANK1948]

I noticed my hydro boost is leaking from were the master cylinder bolts up the hydro boost still works fine. does these usually go bad? the dealer says a new one is $800!!! but they also have a acumulator rebuild kit is this what i need plese advise. this problem from my 96 crew cab dually

[rjschoolcraft]

The hydroboost units do occasionally go bad. Mine did a while back. I replaced the whole thing with a rebuilt unit from Carquest... much cheaper than the dealer price. I considered the rebuild myself, but decided the truck would be down for less time if I just swapped for a rebuilt unit. There was an article on the DP a while back. It may be in the reprint volumes by now.

[cruzer]

Are you sure it's power steering fluid and not brake fluid?

[wilpulu]

FYI...I accidentaly filled my power steering reservoir too full,in doing so acquired the leak under the master cylinder. Took it to the shop and like you mentioned, $800 is what they wanted. I figured I'll just add power-steering fluid and save the money. Well once the PS level got back to where it should be I'm thinking the pressure came down and bingo, no more leak. Very glad I didn't waste $800!!!! So if your PS reservoir is not at max capacity your leak is probably for real. Later

[JMY19]

I had the same issue. I was going through a full tank of power steering fluid every couple of days. I filled it up with Lucas Oil stop leak from Advanced Auto and I havent had to touch it again since. Brakes work fine too.

[ucdavis]

I used Lucas Oil Stop on mine too & it seems to be holding. It might become my favorite additive, cuz replacing the pump in my rig is too terrible to contemplate.

[ssybert]

Maybe you guys can offer a suggestion to my situation....


I've got a problem where I continue to fill my BRAKE resevour (sp?) and it ends up down in my Power Steering system, overflows the PS resevour and keeps leaking all over the ground.

Do I need to replace the booster? Sures sounds like it to me :-/

[CareyWeber]

Originally posted by ssybert:
Maybe you guys can offer a suggestion to my situation....


I've got a problem where I continue to fill my BRAKE resevour (sp?) and it ends up down in my Power Steering system, overflows the PS resevour and keeps leaking all over the ground.

Do I need to replace the booster? Sures sounds like it to me :-/ ssybert,

It sounds like you need to replace the master cylinder, and then a complete flush of your power steering system as it

[ssybert]

What is the difference between the master cylinder and hydro booster? I thought they were the same thing?

[cruzer]

The master cyl makes the brakes work. The hydro boost is a power brake booster. It makes the brake pedal easy to push down. In a car w/a gas engine with power brakes uses a power brake booster which works off of engine vacuum. It would be the big round thing behind the master cyl. A diesel engine has no vacuum so they use hydrolics. You will also find these units on 3/4 & 1 ton gas trucks too. The power steering pump supplies the hydro booster. The master cly & hydro booster are 2 separate systems.

Generally, a bad master cyl will leak fluid from the rear of the cyl, where it bolts to the booster or fire wall if it has manual brakes(no booster).

[ssybert]

The master cylinder is NOT leaking BRAKE fluid. The problem is the BRAKE fluid is somehow getting INTO the power steering fluid and overflowing the PS pump out of the cap onto the ground. I keep filling the BRAKE fluid and the PS fluid keeps OVERFLOWING. :-/

[cruzer]

I have never separated the 2 parts, so I don't know the internals of the booster. The brake fluid must be leaking into the low pressure side(return) of the booster, if thats possible. I would bet if you unbolted the master cyl you will find it is leaking into the booster. Brake systems are self contained. Brake fluid becomes low because the brake pads wear and the fluid takes the place of the worn pads/shoes or there's is a leak some where in the system(calipers, wheel cyldrs. proportioning valve,brake lines or MASTER CYLDR). It is not uncommon for a master cyldr to leak into a vacuum brake booster w/no fluid showing on the outside. I guess it would be possible for it to leak into the hydro booster too. Is there anybody out there who has had the hydro booster apart. Can brake fluid get into the PS fluid?

[NH2112]

$800? That's what you get for shopping at the stealership. I picked up a reman hydroboost at NAPA a few years back for $170 or so, I think the core was $70. We did a lot of business with them at work so he didn't even charge me the core charge, as long as I brought the core back the next day.

[tom.mcinerney]

The hydroboost assemblies have been around for 30 years or so. They tend to be reliable even after they start to leak PS fluid [good to maintain, though]. The remans are probably a good fix, good price.
I was shopping for brake components recently, and found a shop worth mentioning:
<http://www.hydroboost.com/> Email: info@hydroboost.com
Telephone (586)427-6970 Snail mail/Shipping Address
Hydratech Braking Systems 26642 Haverhill Warren, MI 48091
Hydratech provides updated [2004] OEM factory-new boosters for $350

[damork]

I had a 83 Jimmy with a 6.2 diesel and the hydroboost started leaking at about 185000. The GM dealer had a parts person who knew right away that I needed a kit so I bought it and installed it in a parking lot with a small tool kit.

The roughest part was getting the firewall bolts and linkage undone and the big nut holding the rear part of the unit together if I recall correctly. Once apart, the new seals were easy to install and it went together just fine. I ran it another 20k with no problems. I just don't remember the kit number, but was close to $100.

[tom.mcinerney]

TDP member Bill Efland recently rebuilt his hydraboost. He had difficulty obtaining the proper seal for the main pushrod shaft [i think]. In the open email forum a European member responded that he , too, was unable to get right seal . In my online search that yielded the reference in above post i was actively searching for a solution to this seal/kit deal.

My hazy recollection is that i received an email from a rebuilder stating that the newer hydraboost assemblies incorporate a pushrod shaft which is articulated about a sort of balljoint. The diameter of the flexjoint requires its disassembly for the successful seal installation. An expensive hydraulic tool is employed by rebuilders. {my recollection of story}

It seems to me that the joint only needs strength in compression, could probably be hacksawed/pried open, then closed with channellocks/visegrips/hammer following seal installation....

At that point I believe i was referred to:
Precision Rebuilders, Inc. 350 North Commercial St. Clair, MO 63077
Local: 636.629.1444 Toll free: 800.325.2690 Fax: 636.629.4382

That's where i left the trail cold. It would be nice to know if any kits have all the seals; and if there's a work-around the joint issue. Maybe the TDP article/reprint (mentioned by ronniejoe above, 12/'03 post) has all ready solved this mystery...

[CareyWeber]

Originally posted by ssybert:
The master cylinder is NOT leaking BRAKE fluid. The problem is the BRAKE fluid is somehow getting INTO the power steering fluid and overflowing the PS pump out of the cap onto the ground. I keep filling the BRAKE fluid and the PS fluid keeps OVERFLOWING. :-/ ssybert,

They are two completely seperate systems Master cylinder has brake fluid in it, the Hydro boost unit uses powersteering fluid.

If you are adding brake fluid and it causes your power steering to over flow then you have a leak at your master cylinder (where the master and the hydro boost mate is the only place the two fluids can mix).

Carey

[Brandon]

There is a drain hole between the hydraboost and the master cylinder. It is very unlikely that you should have a fluid exchange between the two. When the shade tree guy rebuilds a hydroboost he can only replace two of the seals and not all nine pieces in the kit. If it is leaking out the front then you need the seal kit GM# 456226. The two seals can be changed with the hydroboost is still on the truck since all you need to do is remove the six bolts in the hydroboost and remove the master cylinder. If the hydroboost is leaking at the firewall then you need to install a NEW one. Remember when you buy a reman you buy SOMEONE ELSES OLD PROBLEM. The dealer might be more but how many times do you want to change one.

[96turboSuburban]

Excellent advice given here!!! ;)
I too have a leaky hydroboost and plan to replace it with a new one since it is leaking at the firewall :eek: :eek: :(
Mileage:188K, surprisingly close to the mileae someone else here had when they had troubles too!!
96Turbo....

[eracers999]

Had the same situation, hydro boost leaking at the firewall, cost me 49 cents to fix. Took unit apart and installed a o ring in side the bigger seal. Cant remember exact seal but it is the one that was resposible for the leak. Still in service 4 years later.

Kent

[additive]

All,
Is there any easy way to get the clip off so I can slide the rod and brake light switch off? I seem to be bending it pretty good and I still can't get it off.

Additive

[ 06-25-2005, 11:46 AM: Message edited by: additive ]