73 GMC 2500 Hydroboost/locked brakes after hose replacement - The 1947 - Present Chevrolet & GMC Truck Message Board Network

73FrankenTruck · 03-09-2015, 01:30 AM

So as I'm cracking into this new project, I've hit a stop that I cannot get around:

History: 73 GMC 2500, 454. Converted to 1-ton dually. truck arrived to me with zero coolant. Replaced heater core, thermostat, all coolant related hoses, flushed coolant system. Went for test drive. Filled up gas tank. Truck drove, turned, and stopped fine. As soon as I (parallel) parked it, saw smoke from under hood. Driver side inner fender had fresh fluid on it. Upon further inspection, the hose from hydroboost booster to the steering box had a pin hole leak.

What I did/what happened: replaced aformentioned hose. Topped off power steering fluid. Started truck, turned lock-to-lock about 40 times while repeatedly pushing brake pedal. Fluid level was same. Put in gear...brakes are locked up. I tried the lock-to-lock deal again, same result. I've researched threads on here, but what i've read always seems to involve replacing the booster. I just swapped a hose. Everything seemed to be working fine.

Any ideas? Am I not doing something correctly? Thank you for any insight.

-C

v30crewcab · 03-09-2015, 12:49 PM

did you have the wheels off the ground while turning them? and you need to do this with the engine off. don't need to push the brakes while turning. bleed all the air out of the power steering,and the hydro will bleed itself.

73FrankenTruck · 03-09-2015, 06:43 PM

Quote:

Originally Posted by v30crewcab

did you have the wheels off the ground while turning them? and you need to do this with the engine off. don't need to push the brakes while turning. bleed all the air out of the power steering,and the hydro will bleed itself.

No, I did not have the wheels off the ground while doing it. So put it on jack stands, and turn wheel lock-to-lock with engine off? Same deal, about 30-40 times lock-to-lock? What does lifting tires off ground do?

cerial · 03-10-2015, 04:52 AM

Bleed your breaks.

I am guessing you have a collapsed rubber line. It is a common thing on our hydro boost trucks. I have had 3 right front "soft" lines go bad on various trucks over the years which caused the break to lock up for around a hour or more until the line opened back up. It only happens when you use the breaks a lot or push them hard. I could see you driving it normal then pushing on the breaks many times parking.

v30crewcab · 03-10-2015, 06:27 PM

you have to do it with the wheels off the ground, and the engine not running, to get fluid with no air in it moving thru. if its running it gets all foamed up and pumps air everywhere, and doesn't bleed out correctly. with the wheels on the ground it can actually kill the ps pump. with it off the ps box pushes the fluid back and forth and works the air out.

73FrankenTruck · 03-30-2015, 11:19 AM

UPDATE:

So I finally got around to this. Put the truck up on jack stands, went through the bleeding process. Before I set it down, I noticed I could spin the passenger front tire, but not the driver side. I cracked the bleeder valves, and it seemed to help, but I think I was just delirious from frustration. The driver side caliper would not budge.

I'm wondering if I botched it up pumping the brakes repeatedly while thinking I was bleeding correctly. Regardless, I replaced the calipers and pads. I went to replace the rubber brake lines since that seemed to be a recurring piece of advice. Nothing from the parts store would match up (not my first headache in obtaining parts for this mismatched build). I ended up getting some made ($25 for both) to match the ones I took off.

Everything seemed to be great. Truck moved, ran, and stopped. I noticed the next morning that as soon as I started the truck, the pedal was HARD and I had no power steering for about 3 seconds...then everything was fine. As I drove, the pedal would have a ton of travel, really soft. If you pumped the brakes, it would be normal again. The only thing I could think was I had fried the power steering pump (again, while I thought I was bleeding correctly with truck on ground). I rolled the dice at the parts store without taking my old pump in. Of course it wouldnt be the right pump. Back to match it up. With minimal automotive knowledge, this is fast becoming the most frustrating part. Pump replaced, did both belts while I was at it. Rebled power steering again.

EVERYTHING WORKS.

I know these are simple tasks for most everyone here, but I cant even begin to explain the relief I feel now. Now onto fixing all the other BS that I have no idea where to begin with. Thanks for everyone's advice!

03-09-2015, 01:30 AM	#1
73FrankenTruck Registered User Join Date: Mar 2015 Location: Tacoma, WA Posts: 8	73 GMC 2500 Hydroboost/locked brakes after hose replacement So as I'm cracking into this new project, I've hit a stop that I cannot get around: History: 73 GMC 2500, 454. Converted to 1-ton dually. truck arrived to me with zero coolant. Replaced heater core, thermostat, all coolant related hoses, flushed coolant system. Went for test drive. Filled up gas tank. Truck drove, turned, and stopped fine. As soon as I (parallel) parked it, saw smoke from under hood. Driver side inner fender had fresh fluid on it. Upon further inspection, the hose from hydroboost booster to the steering box had a pin hole leak. What I did/what happened: replaced aformentioned hose. Topped off power steering fluid. Started truck, turned lock-to-lock about 40 times while repeatedly pushing brake pedal. Fluid level was same. Put in gear...brakes are locked up. I tried the lock-to-lock deal again, same result. I've researched threads on here, but what i've read always seems to involve replacing the booster. I just swapped a hose. Everything seemed to be working fine. Any ideas? Am I not doing something correctly? Thank you for any insight. -C

03-09-2015, 12:49 PM	#2
v30crewcab Registered User Join Date: Apr 2012 Location: Chatt Tn Posts: 982	Re: 73 GMC 2500 Hydroboost/locked brakes after hose replacement did you have the wheels off the ground while turning them? and you need to do this with the engine off. don't need to push the brakes while turning. bleed all the air out of the power steering,and the hydro will bleed itself. __________________ 88 military v30 crewcab shortbed 5.9 cummins, nv4500, 205 86 k30, 89 diesel burb, 76 gmc pathfinder 71 longbed 5.3 4l80 http://67-72chevytrucks.com/vboard/s...d.php?t=522535

03-10-2015, 04:52 AM	#4
cerial Registered User Join Date: Mar 2014 Location: Ionia, MI Posts: 199	Re: 73 GMC 2500 Hydroboost/locked brakes after hose replacement Bleed your breaks. I am guessing you have a collapsed rubber line. It is a common thing on our hydro boost trucks. I have had 3 right front "soft" lines go bad on various trucks over the years which caused the break to lock up for around a hour or more until the line opened back up. It only happens when you use the breaks a lot or push them hard. I could see you driving it normal then pushing on the breaks many times parking. __________________ 1991 Metro commuter 1991 s10 future project truck 1987 V10 backup daily/junk truck 1985 K20 Winter beater 1991 R30(squarebody) c/c flatbed towrig 1994 s10 80"wb custom build

03-10-2015, 06:27 PM	#5
v30crewcab Registered User Join Date: Apr 2012 Location: Chatt Tn Posts: 982	Re: 73 GMC 2500 Hydroboost/locked brakes after hose replacement you have to do it with the wheels off the ground, and the engine not running, to get fluid with no air in it moving thru. if its running it gets all foamed up and pumps air everywhere, and doesn't bleed out correctly. with the wheels on the ground it can actually kill the ps pump. with it off the ps box pushes the fluid back and forth and works the air out. __________________ 88 military v30 crewcab shortbed 5.9 cummins, nv4500, 205 86 k30, 89 diesel burb, 76 gmc pathfinder 71 longbed 5.3 4l80 http://67-72chevytrucks.com/vboard/s...d.php?t=522535

03-30-2015, 11:19 AM	#6
73FrankenTruck Registered User Join Date: Mar 2015 Location: Tacoma, WA Posts: 8	Re: 73 GMC 2500 Hydroboost/locked brakes after hose replacement UPDATE: So I finally got around to this. Put the truck up on jack stands, went through the bleeding process. Before I set it down, I noticed I could spin the passenger front tire, but not the driver side. I cracked the bleeder valves, and it seemed to help, but I think I was just delirious from frustration. The driver side caliper would not budge. I'm wondering if I botched it up pumping the brakes repeatedly while thinking I was bleeding correctly. Regardless, I replaced the calipers and pads. I went to replace the rubber brake lines since that seemed to be a recurring piece of advice. Nothing from the parts store would match up (not my first headache in obtaining parts for this mismatched build). I ended up getting some made ($25 for both) to match the ones I took off. Everything seemed to be great. Truck moved, ran, and stopped. I noticed the next morning that as soon as I started the truck, the pedal was HARD and I had no power steering for about 3 seconds...then everything was fine. As I drove, the pedal would have a ton of travel, really soft. If you pumped the brakes, it would be normal again. The only thing I could think was I had fried the power steering pump (again, while I thought I was bleeding correctly with truck on ground). I rolled the dice at the parts store without taking my old pump in. Of course it wouldnt be the right pump. Back to match it up. With minimal automotive knowledge, this is fast becoming the most frustrating part. Pump replaced, did both belts while I was at it. Rebled power steering again. EVERYTHING WORKS. I know these are simple tasks for most everyone here, but I cant even begin to explain the relief I feel now. Now onto fixing all the other BS that I have no idea where to begin with. Thanks for everyone's advice!



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