1986 GMC C6000 PS fluid running out from between the MC and Hydro booster

[Gate keeper]

At some point I bought a 1986 GMC C6000. It's a running rust bucket I'm working to restore. So far the rodents have got more use out of it than me. Problem is the Hydro booster. I'm here because I hope someone can help me. Haven't even drove it yet. I'd just start it and move it a little to keep it happy. One day the PS fluid began running out from between the MC and HB flashings. Figuring it was a seal, I replaced it with a remanufactured one, which also poured fluid. Since then, I've replaced it two more times, in a row. As soon as I fill it and start it, it pours out. I'm either doing something wrong or these remans aren't worth a damn. I don't know if there is limiter valve in the pump that has blown out or something else. Not sure what to think on this one, but I could use some old school advice.

 

[schiker]

This is the correct thread to reply to sorry about any confusion.

I don't know much. I replaced my hyro boost a few years ago.

When I installed mine iirc I put the return hose to a bucket and it would dump a return stroke of PS fluid when I let off the pedal. Again its been a while seems I turned wheel lock to lock and would press pedal slowly then when I let off it dumped the stroke in the bucket. I kept topping off PS fluid and continued until it was cleaner fluid coming out.

How is it you are purging fluid and air? Or are you just attaching all the lines and starting up and it starts pouring fluid out between MC/HB? Do you have the return unhooked does fluid come out return line immeditately when started?

 

[Gate keeper]

This is the correct thread to reply to sorry about any confusion.

I don't know much. I replaced my hyro boost a few years ago.

When I installed mine iirc I put the return hose to a bucket and it would dump a return stroke of PS fluid when I let off the pedal. Again its been a while seems I turned wheel lock to lock and would press pedal slowly then when I let off it dumped the stroke in the bucket. I kept topping off PS fluid and continued until it was cleaner fluid coming out.

How is it you are purging fluid and air? Or are you just attaching all the lines and starting up and it starts pouring fluid out between MC/HB? Do you have the return unhooked does fluid come out return line immeditately when started?

The fluid is actually clean. It's had around 2 gallons of fresh fluid applied during prior failed installation attempts. I was connecting all lines and starting it. But then I tried something similar to what you've asked. The return was directed back into the top of opened reservoir. The input barb was closed off. I know air can make it through the seals, but shouldn't they seal once the fluid fills the chamber?

 

[schiker]

How much leakage are we talking about? Now that you mention it mine wept some fluid out of a weep hole on the underside of the bore. I was worried about it first and think there is an old post on it here somewhere. I think its lube so the bore won't rust on the shelf.

It might have to stroke back and forth a few times to get all of this storage "anti-rust" out.

I sprayed some brake cleaner in the weep hole to encourage it to finish up weeping.

In addition to any anti-rust like you say air could be causing it too. It might be air bubbling past seals and allowing fluid to leak past. I think it has to purge all the air out of the pressurized side ie turning the wheel back and forth lock to lock and pressing the brake letting it dump out til everything seals up. Then "burbed" it probably has to connect the return line and circulate until all the air quits.

Feel for the weep hole or a notch on the flange where it bolts to the MC and see if that is where the leakage is coming from.

 

[schiker]

The PS pump is a vane pump I think it will sorta self-limit pressure. But with age, something might have stuck.

For reference, I think mine wept maybe a 1/4-1/2 cup or so of fluid??? Not constant but wet the frame under the HB. It did not pour out that I remember. Might have dribbled-dripped some over a few days.

 

[Gate keeper]

Thanks Schiker. It's not a drip or a dribble, it's a full blown facet flow. There is not weep hole. It just flows between through the surfaces as if there is no seal resisting any fluid. This is even without the return line connected to the pump intake barb, but rather directed into the uncapped reservoir port. I've almost got a mind to rip it apart just to see if the seals are even in there or if they're backwards. What kills me is every HB I've put in this truck does the same thing in the same way without fail. I can't believe this. Very puzzling and frustrating but I'm not giving up. I appreciate everyone taking their time to offer some pointers and suggestions.

 

[EWC]

This have the 2 master cylinder brake system ? One on the firewall and another under the truck mounted to the frame under the seat ? I would almost try taking off the master cylinder and starting the truck to see if the seals are blown . Are the pressure return lines on correctly ?

 

[red]

There is a relief valve in the pump, when the steering is cranked all the way to the stops and you keep pulling on the steering wheel you can hear it open up.

Bad rebuilds are a good possibility. Bored the cylinder out but still running the original sized seals that are now too small, wouldn't be the first time that's happened.

 

[Gate keeper]

This have the 2 master cylinder brake system ? One on the firewall and another under the truck mounted to the frame under the seat ? I would almost try taking off the master cylinder and starting the truck to see if the seals are blown . Are the pressure return lines on correctly ?

It has one MC. If I have time tomorrow, I will loosen up the MC and pull it back to see what's happening with the HB after starting the motor before I remove it to dissect. The pressure lines have fittings and angles that only allow one order of attachment. The lines are in the only configuration allowable. Thanks . I'll give your seal test suggestion a try. Dave

 

[Gate keeper]

There is a relief valve in the pump, when the steering is cranked all the way to the stops and you keep pulling on the steering wheel you can hear it open up.

Bad rebuilds are a good possibility. Bored the cylinder out but still running the original sized seals that are now too small, wouldn't be the first time that's happened.

That makes perfect sense. It's something I didn't consider. When I pull it apart, I'll make some notes of how firm the seals are, their condition and position. It wouldn't cure the problem, but it will let me know what it takes to solve it. It would at least be a step in the right direction. Good advice. Thanks. Dave

 

[Gate keeper]

There is a relief valve in the pump, when the steering is cranked all the way to the stops and you keep pulling on the steering wheel you can hear it open up.

Bad rebuilds are a good possibility. Bored the cylinder out but still running the original sized seals that are now too small, wouldn't be the first time that's happened.

Also, it pours out of the seals without any restraint through the return line. It flows through the return line which I had directed through the top port, and the HB/MC flanges, as if the seals aren't even there. So I believe it is not a pressure overload on the seals. Your suggestion about the over bore/loose seals sounds on the mark. I will let you know. Thanks.

 

[Gate keeper]

Update. After everyone left the house today, I dug into it. With it disassembled I studied the seals and surfaces. Everything appeared clean and tight, at first. While assembling it, I discovered something. An external plate, which holds everything in place, tapped in deeper than where it pulled out from. Its original position left the seal very close to the weep hole. Yes, there IS one afterall. After installing it, I wanted to top it off and see how it held up. No fluid. Nothing to be found. All the stores were closed for Christmas. Nothing at my shop 20 minutes away. The fence and gate business will have to wait until the result comes in. I have to get this truck going. To be continued.

 

[Gate keeper]

I forgot to include the images. I hope this was it.

 

[Gate keeper]

The problem is solved. The seal/spring retainer plate was not properly seated. Tapping it tight DID fix the problem. The fluid flowed through, back into the reservoir with no sign of leakage from the HB. So the last three returns to AdvanceAParts were probably good. I'm glad I found it, but what a huge waste of my time and money to get there. I was ready to buy another truck. Now I can keep this ole rust bucket, refurbish it and put it to work, almost.
My battery is not charging. Either the rats and squirrels ate some wires or the alternator or regulator took a dump. I know the rodents have been busy. Their little nuggets and stash are on the motor and in the cab. Smells like a nest in there I spent a few months about a year ago shaping, cutting and welding sheet metal to the floor. Still looks new, just smells and looks like the neighborhood critters found a new home. Ehh, here I am rambling again. Sorry bout that. So I need to find the regulator in this thing. It it's in the alternator then I guess that has to be replaced.

 

[red]

Glad the leak's fixed.

GM has used internal voltage regulators since at least the early 70's

 

[FellowTraveler]

Yep, hydro-boost can be a PITA but is hands down better than most other systems. I had years ago taken to rebuilding my units because I could not seem to get good rebuilt units sand was my big issue resulting in scratches on the main piston and bore.

As for your alternator there are some real good deals on newer hi-output ones on the web....good luck!

 

[MrMarty51]

Good to know You got the leak stopped up.
use a multi meter, on DC volts setting, alternator should be putting out about 13.5 to 14 volts. Also, try the VOM on AC setting, if it then reads voltage that means bad diodes.

 

[WarWagon]

I suggest you reconsider "this rust bucket" in context of: downtime cost, lack of your time to constantly F with it, the fact it's 30+ years old, with serious mice wireing damage.

What does it cost you or paid employee per hour to sit on the side of the road waiting for an EXPENSIVE tow?

What do you think your customers first impression is going to be when(if) your crew shows up in a POS looking rig? I assume it looks bad from the name.

Got no issue helping you get it going, but, considering you have to ask for help on the wireing I predict it's going to be expensive to pay a shop to fix it and fix it "NOW!" And said towing, lost revenue, paid wages broken down doing Nothing, will erase any savings on forcing this rust bucket to continue to "work".

And one last thing: "you want me to drive to the job in this POS!?" Yeah, see ya I be working elsewhere with better equipment tommorow. It's the driver's ticket if the damn lights don't work etc.

Some nice older rigs out there and I hope this is going to be one of them before you put it back to work.

 

[btfarm]

Moved thread from intros

 

[Gate keeper]

Yep, hydro-boost can be a PITA but is hands down better than most other systems. I had years ago taken to rebuilding my units because I could not seem to get good rebuilt units sand was my big issue resulting in scratches on the main piston and bore.

As for your alternator there are some real good deals on newer hi-output ones on the web....good luck!

Thanks FellowTraveler. A rebuild kit was my first choice, but I couldn't find one. Wasted money trying a generic kit. Anyway, I got it figured out. The final retaining plate was not fully seated. I tapped it in until it was tight and like magic, no more leak. I would bet the 2 before that, had the same problem.