tsb on hydroboost problem?

[typecast]

My truck was towed in this morning -- no power steering / brakes. Called a little while ago and svc manager said the tech was still trying to diagnose the problem.

Wondering if I can help him out with a tsb or something from GM. Any techs out there know of more info?

Thanks,

Galen

[MaxRock]

typecast,

I am not aware of a tsb on the hydroboost, but all I know is my master cylinder is leaking in the cab. The dealer has a new hydroboost on order and will replace mine on Tuesday.

MaxRock

[ 11-10-2003, 07:16 AM: Message edited by: MaxRock ]

[xwing]

Maybe your hydraulic pump snapped its shaft deep inside the pump, like mine and some others' have. You can tell by trying to pry the pump pulle forward with a screwdriver or something; if it shifts forward a half+ inch you snapped the shaft. It still runs fine, doesn't fall out, but the shaft can snap deep inside because it has a defective design that necks down alot from the shaft diameter you SEE on the outside. I did it just by laying on the brakes for all I was worth. There SHOULD be a TSB on this, and IMO a recall for a better pump design.
The freaking STEERING and BRAKES on these heavy towing trucks is a MAJOR safety item and these pumps should NEVER snap a shaft!!
I have heard some others have had a valve get stuck and lose power awhile.

[typecast]

Well my truck has been in the shop since Friday, and they still have not diagnosed the problem of why I have no power steering or power brakes.

I know this can't be all that complicated, but these dudes act like they are in over their heads. The service guy has told me several times that they have "calls into Tech Assist". What the heck is that?

The service department doesn't seem interested in getting any input from me, but surely there is enough experience here to point these guys in the right direction...?

Thanks,

- Galen

[DmaxMaverick]

typecast

Essentially, the current brake/steering system in service has been used on all GM (and most Ford) Diesel equipped vehicles since 1982 (among other HD vehicles). Very few changes have been made to the system since then. The system is generally very reliable. There are a few known issues that effect a very small percentage.

Regarding your problem with the service dept, there are very few components to the system, and none of them are serviceable by the dealer. They are only replaced. The dealer does not repair any of the components.

The test to determine which component needs replacement only takes about an hour, and replacement of any part takes less than 2 hours. Considering your truck was taken in on Friday, it's not likely that they did anything that day. Most service dept's don't work on Sat. or Sun. and today being a holiday, only Monday would have been possible for repair operations. They may not have even raised the hood yet.

Don't get me wrong here, I am not defending the dealer. They have had plenty of time to fix your truck. If they are really stumped, as they indicate to you, I suggest you make arrangements with another dealer to take over. There is no excuse for them not having the truck repaired, unless there is a parts availability issue. At least they could duplicate your complaint, which is 90% of the repair process. You did get a rental, didn't you?

[typecast]

Thanks for the reply. I kind of bought this thing as a second chance for a US built vehicle. I had been driving imports for 10 years because of really bad luck I had with another truck back in 1992. This experience is causing me flash backs.

I think you are right in that these guys have not spent much time looking at my truck. They are pretty laid back. When I talk to them, they make it sound like a bigger deal than it should be -- talking about trying to figure out why I have air in the lines (?) and calls to "Tech Assist".

They did give me a rental to drive.

- Galen

[LB_7]

My truck has been at the dealer's since last Tuesday with the exact same issue. It's an '03 Silverado 2500 HD, D/M with 13,000 miles. I experienced the temporary problem. Steering/brakes went out after sitting for a few days. After removing the PS resovoir cap and playing around for 45 minutes, or so, they came back.

Xwing - I'm curious - did you have the problem on a temporary basis before your shaft snapped? I assume once it's snapped, you got nothing until the part is replaced. Right? Just wondered if that's what's next after a temporary problem.

On another thread I was reading, one guy reported having so much pressure in the system that when he pulled his PS cover, fluid shot around the engine compartment! In my case, the fluid level was elevated, but returned to normal when the systems started working again. Obviously, suggests some sort of stuck valve somewhere. Any chance the extra pressure from a stuck valve causes the shaft to snap (ie it's more of a symthom than the real problem)? Could also explain why the Hydro Boost and master cylinder develop leaks. Threr seems to be concensus on the other threads I've read, though, that the hydro boost is the culprit -- but GM technical Support there's so valves in the Hydro boost, so it couldn't be that. Could be a CYA position, though. Any ideas?

I just got rejected for warranty coverage by 3 levels up the GM service organization because the dealer can't replicate the problem. I've told the dealer to replace the hydroboost at my expense. I can't afford to lose my brakes - and then not be able to steer!! My son drives it, too. I also tow a 10K trailer with it!!

I can't believe the total disregard for customer as well as public safety!! Somebody loses their brakes and steering when they're parked on a hill with a load on, people could die!!

Anybody have any other thoughts on what parts I should replace, if any, besides the hydro boost?

Thanks.

Andy

[LB_7]

DmaxMaverick

You seem very knowledgeable. What specific components should be tested by the dealer? I'm working with a very small dealership and they only sell a handful of diesels every year and apparently haven't seen this before. The regional gm service rep is stonewalling any repairs until it can be replicated at the dealership.

What's the most likely culprit - the hydro boost or the pump?

Also, will the one hour of testing be of any value if the system seems to be working again? Can the test(s) detect a small change from a prior failure that would lead to finding the problem part?

I'm really frustrated. Haven't had my truck in over a week and nothing is apparently going to be done about this problem unless I can help lead them in the right direction!

Thanks.

Andy

[Phil B.]

Andy,

I received your emial via TDP. Although my dealer agreed to replace the hydroboost on good faith, I have not yet had the unit replaced. I've been waiting for the next time for the steering and brakes to go out before taking it back in for the replacement. So far, it hasn't occurred again...

Mine has always failed when first turned on, never when the engine has been running.


Phil B.

[xwing]

I am a big GM supporter but if GM by now DOESN'T have their engineers AND lawyers on the Hydroboost Failure Situation, they aren't as smart or legally competent as I suspect they are...failure of BRAKES AND STEERING ASSIST in 3 ton+ trucks, towing 10,000lbs or more sometimes, is very dangerous...whether intermittent, or permanent (as in my case where the pumpshaft snapped at the faulty-design pumpshaft where it narrows down so much it snapped when the brakes were applied for all I was worth once).

One wonders how hard it would be to find out about the "double-secret-probation" problem list they must keep on such safety issues...
I just want them to redesign the pump (and then give ME one) so it has a proper shaft thickness, so it can't break EVER AGAIN, as it NEVER EVER SHOULD in the first place. This should be way OVERdesigned--not so close to the edge at max duty that it can fail in some percentage of cases.

This is NOT a little airconditioning or paint issue. Thank goodness it only has happened to a few of us so far. Number dead due to Hydroboost brake/steering failure SO FAR: 0.
:(

[LB_7]

Zero as far as we know. Who really knows. I'm told this system has been around for over 20 years!!

I found out this same system has been used on passenger vehicles, too. Astro minivans were mentioned. How about if someone's family gets killed or mamed over this mentality??!!

[typecast]

I got my truck back last Thursday. They did end up replacing the hydroboost. They did say there was a flow valve stuck (open or closed, not sure) preventing fluid flow.

My hydroboost failed one time after sitting for 2 days, but started working again after a few minutes. The second time it failed hard, and remained that way for good.

I agree, it is a safety issue. If this happened to me with my 5th wheel in tow, I would be in very bad shape.

- Galen