So last fall the power steering pump on my '91 V3500 started whining every time I hit the brakes. Thinking the pump was on it's way out, I swapped it for a new one and bled the system as per the instructions from forum members here. Unfortunately, the problem still persists, so I'm thinking it's probably a hydroboost issue? I've never had to diagnose a hydroboost problem before, and would appreciate it if anyone could steer me in the right direction. According to the receipts from the previous owner, the hyroboost unit was replaced with a new/rebuilt one about two years ago.
CK5
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Hydroboost problem?
- Thread starter point-five-o
- Start date
Could be, but none of them are kinked. I guess I could try removing them and blowing compressed air through 'em to see if there's a problem I couldn't see.
wheel400
1/2 ton status
hows your braking... does it pull or anything like that?
I haven't noticed any pulling, but now that you mention it, one of the rear tires has been locking up under marginal brake pressure. Do you think it's related?
wheel400
1/2 ton status
yeah It could be.. were you able to get all the air out of the lines?
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Not sure . . . thought I did, but I was either unsuccessful in fully bleeding the system, or air is somehow getting into the system after the fact. That's the only thing I've been able to determine anyway.
MrSchaeferPants
1/2 ton status
Bleed again and check for air bubbles in the resiviour.
Not sure what your procedure was, I always jack the front up, make sure it's topped off, start the truck, slowly turn wheel from lock to lock a few times until it stops whining, add fluid as needed, wait for the bubbles to dissipate, this gets the majority out.
After the foam settles, top off, then press and hold the brake pedal, and turn the wheel lock to lock. If you have a lot of bubbles, stop and wait for the foam to settle down, make sure it's topped off, and do it again and again with the pedal down till there's no more foam. The thing is, if it's super frothy, stop and wait for it to settle down, otherwise you're sucking it back in. These systems are pretty much self bleeding, but starting from scratch you do need to bleed it before you drive just to help it a long.
Bleed it again, see if the problem goes away, then comes back after some use. If it does, somehow air is getting back in the system. Check your return line(s).
Troubleshooting a hydro boost. With the engine off, press the brake pedal a few times to discharge the accumilator. Now hold your foot down with decent pressure, not full force. Start the engine, the pedal should fall then immediately you should feel it trying to pump back up.
Not sure what your procedure was, I always jack the front up, make sure it's topped off, start the truck, slowly turn wheel from lock to lock a few times until it stops whining, add fluid as needed, wait for the bubbles to dissipate, this gets the majority out.
After the foam settles, top off, then press and hold the brake pedal, and turn the wheel lock to lock. If you have a lot of bubbles, stop and wait for the foam to settle down, make sure it's topped off, and do it again and again with the pedal down till there's no more foam. The thing is, if it's super frothy, stop and wait for it to settle down, otherwise you're sucking it back in. These systems are pretty much self bleeding, but starting from scratch you do need to bleed it before you drive just to help it a long.
Bleed it again, see if the problem goes away, then comes back after some use. If it does, somehow air is getting back in the system. Check your return line(s).
Troubleshooting a hydro boost. With the engine off, press the brake pedal a few times to discharge the accumilator. Now hold your foot down with decent pressure, not full force. Start the engine, the pedal should fall then immediately you should feel it trying to pump back up.
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I can't remember who, but somebody here told me that it works better to push the tires side to side instead of the steering wheel for bleeding. Any issues with the steering? If that's just fine, check the return line - maybe it is swelling or collapsing from age. Some guys swear that hydroboosters never fail, except when they leak. Any chance the belt is slipping a little?
wheel400
1/2 ton status
Hydroboost problem..
you move the steering wheel when your cycling the steering system, not bleeding the brakes..
you move the steering wheel when your cycling the steering system, not bleeding the brakes..
MrSchaeferPants
1/2 ton status
you move the steering wheel when your cycling the steering system, not bleeding the brakes..
Where did that come from
I think you've missed something important in this thread...you move the steering wheel when your cycling the steering system, not bleeding the brakes..
Thanks for all of the tips. I'll run through these and report back to see if I found/fixed anything. I was pretty thorough while bleeding the system the first time . . . lasted for about a day then the whining set in again. From what you and others have said, I guess I'd put my money on bad return lines.
Thanks for your help. I'll double check the belt adjustment, but they were new & properly adjusted last fall when this started happening. The steering whines quite when I'm turning fast/moving slow (like when backing my camper into place), but other than that, it's only when I hit the brakes. I'm gonna inspect all lines one morning this week before work.
