No Power Steering or Brakes?

[DMAX_Phil]

For the third time in six months, when I went out to start the truck I had no power brakes or steering. Last time this happened, I had it towed to the dealer but the problem disappeared and it worked fine for them. Today when it happened I tried restarting it several times and I finally just let it sit for a couple of hours. When I went back to start it up, everything was fine.

A while back I searched and found some posts with others that had experienced this problem and their fix. Now I can't find these posts. I think the problem was identified as a stuck check valve (power steering pump or hydroboost?). Anyone have this problem and know the fix?

Thanks for the help.

Phil

[mackin]

More then likely it's the Hydro boost.....My 98 would do the exact thing primarily on start up cold,had it replaced.....Have you seen any seepage or leaks in the vicinity of the brake reservoir,hydro booster???

MAC

[DMAX_Phil]

Thanks for the response Mac. I haven't noticed any seepage but I haven't looked for it either. I'll take a look.

There were some members here who experienced the same problem with their DMAXs. I just can't find the posts. Did the forum get rid of some/all of the archive messages prior to 1/1/02?

Phil

[chuntag95]

DMAX Phil,

My father-in-law just reported the exact same thing. :eek: Did you ever get it fixed? If so, what was the cause?

[DMAX_Phil]

The dealer called GM and they agreed to replace my "hydro boost" (as Mackin suggested). According to GM, this is the only item that could cause both brakes and powersteering to loose power. I haven't had it replaced yet but will shortly. The dealer is actually working with me on replacing something that they can't verify, a nice change from previous experiences.

When this problem occurs, if I wait long enough, the problem goes away. Problem is it has taken several hours to "cure" itself. Not sure if it is a stuck check valve, or what. I am not at all familiar with this trucks vacuum system.


Phil B.

[chuntag95]

Phil,
Thanks for the update. I told my father-in-law about Mac's suggestion as well. His truck is out of warranty, so it would be out of his pocket. He pulls heavy often and if it happened with him loaded, it could be really dangerous. He said if it happens again, he will replace the Hydro Boost. Any idea what those go for?

[Merconvert]

Hi Dmax_Phil

My brother,has a 01 2500. He had that problem,several times. His dealer,Sunrise in N M. Said it was a vac. Valve in the tranny. Replace it. No problems since. His truck was out of warranty also. $ 316.00 was his bill. My 01 3500 cc long bed 30,000 runs great Love my Truck.

Something to ask your Dealer?

[FirstDiesel]

Merconvert

I don't understand that one. How can a valve in the tranny coause no power steering and brakes?? Also since the dealers are really not do tranny repairs on the Allison I'm even more confused about that repair?? Any chance your friend misunderstood??

[truckin]

Same thing happened to me this morning. I had no brakes or power steering. I shut off the motor and opened the reservoir on the power steering pump. It was under a great deal of pressure and blew power steering fluid out when I opened it. The level was also high. I put the cap back on and proceeded to back down the driveway and at the same time worked the steering back and forth. The brakes and the steering suddenly started working and upon checking the fluid level I found it normal again. My dealer did not have a clue as to why it did this. Is the hydro booster replacement a sure fix? :confused:

[FirstDiesel]

truckin

Sure sounds like something like a check valve was hung. Built up pressure since the fluid was being pumped but had no place to go. Sounds like since there was pressure the problem would be in the booster and not the pump.

[Merconvert]

Firstdiesel

Sorry I goofed, the tranny valve was a different Problem!! Yes G M does let dealerships work on the trannys. My Brother said he had the lost of Brakes and steering after the tranny Prob.
The S M called G M tech,and they stated !! ( They should put a different weight of fluid in the P S!!. Don't think so, Mechcanic said to just let it warm up longer,sounds better,ha ha. Sorry to confuse the issuie, but I confuse easy!!
2001 3500 CC Long bed 30,000 going strong
1968 Merconvert
1929 Model A townsedan runs great,down Hill
1984 T Bird
1985 Cushman Hauler 18 Big Horses
Thanks for the Repley

Bob

[DMAX_Phil]

I also had p/s fluid overflow when this happened the first time. It seems more prone to happen when the truck is sitting for several days. I just got back from Europe and I my truck has been sitting for seven days. We'll see if it acts up.

Not positive but the problem does seem to be a stuck valve and I don't think the problem would occur while operating (under pressure), only on start-up.

[oneton]

Dmax-Phil, I had this problem last year. I went out to start the truck and when I started to pull out I lost all power to the steering and brakes. I crawled under the dash and found the booster was leaking on the inside. GM replaced it and have not had a problem sence. They also installed a shield on the inside as part of the repair so GM does know that there is a problem with the boosters but they are not issuing a recall but just fixing them as they fail.

[DMAX_Phil]

oneton: thanks for the info. Sounds like its got to be the booster. I better get to the dealer before the truck strands me again. I started it yesterday, after sitting for 7 days, and no problem. But of course, I didn't have to be anywhere by a certain time, the problem only occurs when I have to pick the kids up at school or otherwise have a critical appointment...


Phil B.

[oneton]

Dmax-Phil, I forgot to mention that while I was lining up the truck for the tow truck to hook up everything came back all of a suddden. They didn't have to replilcate the situation and didn't question my claim. Goodluck.

[GBurton]

Well it happened to me today. Drove home yesterday, parked the truck and this morning I started to go to town. When I started to back out of the driveway I couldn

[Phil B.]

I jinxed myself by replying to this problem over in the "drivetrain" forum the other day.... Its happened again. Here was my original post and nothing was replaced. After the dealer agreed to replace my hydroboost, I waited to see if it would happen again - well it happened today.

After comparing this thread to the one over in the "drivetrain" forum, I'm not certain if I need to push for a hydrobooster replacement or not. What is the conventional wisdom today?

I hesitate to have it towed back to the dealer, only to have the problem mysteriously fix itself for another two years...


Phil B.

[dieselfish]

I had the same exact problem on my 2005 duramax. The only time mine acted up is when the temp was below freezing. Same blow out when removing the lid and all that you described. Dealer replaced the fluid with a cold temp fluid. I have not had the problem re-occur but also have not had the truck in below freezing temps since the fluid change(freezing temps not to common in Phoenix) . Good luck!

[Xax_XAdo]

okay,

i have read some of the threads here on this problem. i have no power steering or brakes. i have started it a few times - no luck. i just finished the nightmare of replacing the power steering pump and it didn't help either.

so, it is likely the "hydro boost" from what i am reading... i have read where the dealers have fixed this problem. Does it have to be under warranty? Or is it a TSB where they will fix it as it happens? i have 120K on my truck, so it is well out of warranty.

How hard of a job is it to do myself?

[DmaxMaverick]

okay,

i have read some of the threads here on this problem. i have no power steering or brakes. i have started it a few times - no luck. i just finished the nightmare of replacing the power steering pump and it didn't help either.

so, it is likely the "hydro boost" from what i am reading... i have read where the dealers have fixed this problem. Does it have to be under warranty? Or is it a TSB where they will fix it as it happens? i have 120K on my truck, so it is well out of warranty.

How hard of a job is it to do myself?

Welcome to the Forums!

Yep. Hydroboost.

It's not likely you'll get help from the dealer with a warranty replacement. The system has been used reliably since ~1980, essentially unchanged. No TSB's or recalls.

Replacement isn't difficult. Just time (and knuckle) consuming. It bolts through the firewall, and the location inside is anything but convenient. Stay away from the "off brand" remans, as replacement is chore enough to do it more than necessary (off brand remans are about 50/50 reliable). The system is self bleeding, so no "after work" to do. You do not need to disconnect the brake lines from the MC, so no brake bleeding, either. Just unbolt the MC and move it out of the way enough to get the hydroboost unit out/in, much like a vacuum booster replacement.

[Xax_XAdo]

this may be an odd question, but the hydroboost is the thing with the brake resevoir on it right?

i ask because i am used to seeing the big vacuum ball attached to it on cars. is this the same thing?

Also, where is the best place to get one? i looked on Rock something, but wasn't sure what i was looking at.

thanks!

[DmaxMaverick]

The hydroboost unit is the thing behind the brake master cylinder, with all the large lines running in/out of it. In the same place a vacuum booster would be on a gasser. www.rockauto.com has them, as well as other sources. Try www.gmpartsdirect.com, too. You are looking for a brake booster.

[Dura-Ration]

The hydroboost unit is the thing behind the brake master cylinder, with all the large lines running in/out of it. In the same place a vacuum booster would be on a gasser. www.rockauto.com (http://www.rockauto.com) has them, as well as other sources. Try www.gmpartsdirect.com (http://www.gmpartsdirect.com), too. You are looking for a brake booster.

DmaxMaverick,
Since this is so hard to to reach and work on, do you have a recommendation as to which brand that you would buy?

[DmaxMaverick]

DmaxMaverick,
Since this is so hard to to reach and work on, do you have a recommendation as to which brand that you would buy?

GM new is best, but they are proud of them ($200+). You'll get the best price for them at www.gmpartsdirect.com. They don't list it in their online catalog (that I could find), call or email them and have your VIN handy (they are good about making sure you get the right part). Next would be a GM reman. I don't know which is available.

www.rockauto.com only lists a Cardone reman, Part # 527359, for $106 (+$50 core). I don't know about the quality of this part, but Rockauto does stand behind their products.

These units rarely fail internally. The most common failure is the accumulator, which leaks down (loss of reserve braking), or leaks PS fluid externally (seepage around the base of the accumulator). Many times, they are misdiagnosed because of a hose leak (or loose), which is common. Many owners have a failed accumulator for many miles/time and never know it. You can test it by counting full brake applications you have after engine shutdown, at different wait periods. First right after shutdown, then at intervals of a few minutes to hours. You should have at least 3 full brake applications after about 2 hours from shutdown. These units can function normally (otherwise) for many miles/years with this failure.

[Dura-Ration]

Dmax, I appreciate the reply. :)

[bones417]

I had this samething happen on my 2007 Classic 3500. The first thing the dealer did was replace the power steering pump. I haven't had the problem since however, since then it is real hard to turn the steering wheel when not moving or moving very slow. So it has gone back to the dealer twice for this first time they replaced the hydro-boost next they replaced the steering box. Still hard to turn, now they are telling me that this is a normal characteristic of this truck. I don't buy that it didn't do this before they started fixing it. I bought the truck to pull trailers and this makes it real diffacult to backup the trailer and since it's a crew cab getting into and out of parking spaces is a chalange when you have to be moving to turn the wheels. Is this normal? I have driven eveything from mini-trucks to 18 wheelers and the only time I've had this happen is on old worn out equipment. I love the truck but it's becoming hard to live with.

[DmaxMaverick]

Welcome aboard, Bones!

Your dealer stopped short of a thorough diagnosis. Unfortunately, that seems to be the norm, these days.

Your problem may require some "out of the box" thinking. If the pump, steering box and hydroboost unit has been replaced, that leaves one component. The lines. they need to be check for restriction. If one were to collapse internally (between the layers), it would not be the first time. Very rare, but it has happened. Other possibilities exist, but if all else has been replaced with the same results, what remains must be the problem. Sherlock Holmes had something to say about the preponderance of evidence, and he was correct.

[DmaxMaverick]

There is one other possibility. The late trucks have adaptive steering effort, which is logic controlled by the BCM. Be sure your dealer checks the sensor values, and steering input effort. There may also be a calibration update available to address the issue.

[Hook_'em_Horns!]

Don't a lot of these problems stem from not servicing the fluid regularly?

[DmaxMaverick]

Don't a lot of these problems stem from not servicing the fluid regularly?

Could be. But, most folks rarely check the fluid level, let alone include it in a "service" interval. I've had better success with synthetic ATF in the system than the PS fluid. I think synthetic ATF is less sensitive to heat and has better lubrication properties. The fluid level fluctuates less, and the pump is more quiet. I have a replacement pump for my 85 I picked up for cheap (new), and have not needed to replace it. The HB unit has been replaced once, at about 200K.

[Hook_'em_Horns!]

Could be. But, most folks rarely check the fluid level, let alone include it in a "service" interval. I've had better success with synthetic ATF in the system than the PS fluid. I think synthetic ATF is less sensitive to heat and has better lubrication properties. The fluid level fluctuates less, and the pump is more quiet. I have a replacement pump for my 85 I picked up for cheap (new), and have not needed to replace it. The HB unit has been replaced once, at about 200K.

Recommended intervals are about the same as the Allison under heavy use. Very easy to do, it takes about a gallon (cheap) and the black stuff that comes out the bottom side is a shocker. After, the PS is smooth and quiet with no binding while braking and backing.

Under heavy repeated braking, heat is definitely an issue and it torches the fluid. I flush mine every 15k or so. I have never seen a PS pump fail when the fluid in the system was maintained.
As you said, most people never check the fluid level in over 100k miles much less change it.

I seem to remember somewhere in the manual was mentioned to Not use ATF. Is the difference synthetic?

[bones417]

Some problems like mine do come from neglected service, however not the case here. I've had the truck one year now and I'm the first owner only 16,000 miles now. When all of this started it was before the 10,000 mile service in fact they changed the power steering pump when it was in for the 10,000 mile service. I have had it back to the dealer one more time, after replacing the steering box there was too much play in the steering wheel. So this time they rebuilt the steering gear, replaces the pitman arm, drag link and steering linkage idler. Still when stoped or moving slow hard to turn sometimes I can't turn it with both arms, this isn't as good as the good armstrong power steering I grew up with, still the dealer say's this is normal. I called Chevrolet so far not a lot of help they just got the story from the dealer and repeated. However I told them if this is normal then I should be able to get in anyone of the dealers many new trucks and it will act the same, they agreed and if it doesn't then they will do what ever they need to to fix. I'm going back to the dealer yet again on Monday to meet with the service manager so he can drive mine and I will drive one of their's so we'll see. I told them if this is normal it's getting traded for a Dodge:confused: my daughter likes the Mega cab anyway she can tilt her seat. I'll let you know.

[Ponderosa JT]

Getting back to the Check Valve. Is this located in the power steering pump or the hydro boost? My 2002 is having the same symptoms of no ps and no pb at start-up. I rev'd it up in neutral and pop! the steering and brakes came back. Service manager at 2 dealers said they have seen this and have replaced the power steering pump because the check valve is in the pump. BTW, no leaks, fluid OK, a little pressure at the pump when I took the cap off.

Jeff

[dually2002]

Lost PS/Brakes after changing fluid. Siphoned fluid out of pump then ran engine breifly to purge lines and system, Lost pressure on re-start. Alldata bleeding procedure has you start engine and pump brakes about 15 times to set accumalator then jack front wheels of ground (If you got big enough jack) start engine and turn steering wheel lock to lock 20 times. Had to bleed air from pump by releasing ps cap very slowly. Resivoir was pressurized. After pressure was released ps/brakes worked normally.