intermittent power steering & brake failure?

[Horse_gal_jen]

Well we have had the worst luck with our 2001 dmax. It's usually a problem a month and this month is no exception.

Recently we have been noticing that after about 45 mins of highway driving, the first time you hit traffic or a city and come on to the brakes to stop, we loose power steering and power brakes.

You can get stopped and steer through it and then all of a sudden it will let go and kick back in. it will do this a few times only when you come to a stop and then quit.

If you don't go on long drives at higher speeds it's fine.

this winter one of the idler pulleys came off while driving and we lost power brakes and steering. We muscled it home and replaced the part quite easily but my initial thought was something to do with this , maybe the belt not tight enough?

The other concern was that we just had two seperate mechanics tear things apart to replace the pipe leading into the water pump and then a second mechanic replaced the water pump after the first one misdiagnosed the problem. Is it possible they didn't tighten a line enough or something. it doesn't seem to be leaking that we can tell.

anyone encounter this situation?

[More Power]

Is the fluid level in the PS pump at the correct level? If air has gotten into the system (due to a low fluid level), you may need to bleed the system.

Jim

[Willy G]

I recently had a similiar problem with my 2007 2500hd (LBZ) Classic. I drove on an interstate for approx. 45 minutes, then I exited off and after coming to a stop at the first red light, my truck bumped/jumped forward, probaly about 2 feet. I actually thought I got rear ended! My foot was completely on the brake. It was extremly sudden and startled me.
Wow! after reading another issue like this it makes me wonder?:

[Mark Rinker]

Horse Gal I cringed when I saw your posting. You guys have had too many problems with that '01.

Time to put her down, and get into an '02-'04 LB7 with low miles and a fresh set of injectors.

Sorry to hear of your continued issues...hopefully you are getting some miles on as well...

[Hook_'em_Horns!]

I had a similar problem, pulled the return line from the hydroboost and flushed the system. Nasty black burnt PS fluid came out. It takes about 3/4 gallon to run clean. Worked fine from then on. I believe GM needs to look at a fluid cooler for the system for HD use.

[JohnC]

I believe GM needs to look at a fluid cooler for the system for HD use.

I'm pretty sure they have one. I know my '95 did and I think my '06 does, but there's too much junk under the hood to tell for sure.

[Hook_'em_Horns!]

I'm pretty sure they have one. I know my '95 did and I think my '06 does, but there's too much junk under the hood to tell for sure.

My ’02 LB7 and ’05 LLY doesn’t, may be in ’06. Easy enough to look through the grill and see only the oil cooler in front of the condenser on the ’05, with the addition of the trans cooler out front on the ’02 instead of under the cab.

Flushing is also a scheduled maintenance item, per my local Service Manager.

[DmaxMaverick]

My ’02 LB7 and ’05 LLY doesn’t, may be in ’06. Easy enough to look through the grill and see only the oil cooler in front of the condenser on the ’05, with the addition of the trans cooler out front on the ’02 instead of under the cab.

Flushing is also a scheduled maintenance item, per my local Service Manager.

The tranny cooler is up front. The cooler underneath is the fuel return cooler.

[DmaxMaverick]

I haven't seen an OEM power steering cooler on any of them. It's easy enough to follow the lines under the hood. Pump --> hydroboost --> return to pump (low pressure line); hydroboost --> steering gearbox --> return.

If you have an issue with both, PS and brakes, it has to be something common to both. That's everything but the PS gearbox. Fluid, lines, pump or hydroboost unit. Pick a starting point. Fluid flow to the gearbox is regulated by the hydroboost unit (not just a pass-through).

[jbplock]

I haven't seen an OEM power steering cooler on any of them..

My 98 K3500 LB/CC 6.5TD had an OE PS cooler. IIRC it was about 4'' wide and the height of the radiator - located on the drivers side near the radiator. I noticed it when I had the cowling off to clean bugs out of the radiator. Seems like I remember seeing a similar one on my 03 but I'm not sure .. have to check next time I have it apart ..

Also, in lieu of flushing the PS fluid (which is better) I pumped fluid out of the reservoir then replaced with new .. repeated this several times until the fluid looked clear and clean.

[DmaxMaverick]

I was referring to the 2001+ models. On many older models, a PS cooler may have been included OEM, or with the HD cooling option. There is no "Heavy Duty Cooling" option with the Duramax engine. It's listed as an option, but selection of the engine automatically includes it. It's the same process as the aux. battery option.

I just checked with alldata. The only power steering cooler listed is for 1/2 tons. It appears to be an option for conventional PS, and OEM on rack & pinion. It is kinda' vague, though.

[Hook_'em_Horns!]

The tranny cooler is up front. The cooler underneath is the fuel return cooler.

Good, that makes more sense…was the (fuel) cooler mounted up front on the LB7? There was an additional one up front on the LB7 that’s not on the LLY.

Not wanting to hijack but, what’s the best way to remove the plastic fasteners on the radiator support to clean bugs and debris from the Cooling Array up front?

[DmaxMaverick]

Good, that makes more sense…was the (fuel) cooler mounted up front on the LB7? There was an additional one up front on the LB7 that’s not on the LLY.

Not wanting to hijack but, what’s the best way to remove the plastic fasteners on the radiator support to clean bugs and debris from the Cooling Array up front?

I'm not sure where the cooler on your LLY went, but it should be there.

For the plastic fasteners, they are a 2 piece gadget. Once you pull out the center piece (the middle button), the main piece should wiggle free. I use a tool I got from my brother, designed for wedging door windows and pulling door panel fasteners on Cadillacs (he's a locksmith). Here's a really bad pic of it:


You can also use a screwdriver or other suitable device to pry up the middle piece, but the tool pulls them w/o damaging, even the most stubborn fasteners (not to mention quicker and a lot less frustrating). If you damage the fasteners, they are not expensive to replace, and you can get them from Napa, Autozone, etc. The tool can be had through a locksmith supplier for about $12. I can provide the brand name and stock # if needed.

In regards to hijacking the thread, if you need to discuss this off-topic further, start another thread and I'll move these posts into it.

[Hook_'em_Horns!]

In regards to hijacking the thread, if you need to discuss this off-topic further, start another thread and I'll move these posts into it.

No need, just some quick input…we drifted to coolers and it’s on my list to clean out the bugs up front. I had assumed the use of something similar to a door panel tool, only smaller was used, Thanks.