intermittant powersteering issue

[Stlheadake]

I have a friend who just bought his 06 LBZ K3500. He has been complaining to the dealer about an intermittent power steering problem he is having. After the truck has sat for a period, start it up and turn the wheels and the power steering 'fades' and it becomes difficult to turn for a very short period. This goes away nearly immediately. Dealer can't seem to notice the issue.

Now mine is doing the exact same thing. The only difference is that mine doesn't have to sit for any real time at all. I can be sitting at a stop light and then take off, and the power steering will fade away, then come right back.

I have checked PS fluid levels in both vehicles, and both are right where they ought to be. This isn't a dangerous thing (YET), but it really is annoying!

Anyone else been here?

[madmatt]

On earlier years, there was an updated P/S pressure valve that would fix a "similar" issue.

OR,,,,,,does this sound like your problem,,,,,

"Some customers may comment on a lack of steering assist when stopped or during parking lot type maneuvers. A lack of steering assist could occur if the brakes are applied and turning the steering wheel with the vehicle stopped or during parking lot type maneuvers. This condition will go away or greatly improve once vehicle begins to move or is above parking lot speeds. This concern can be aggravated by worn tires, low tire air pressure, low power steering pump pressures, and tires larger than stock size."

[Stlheadake]

On earlier years, there was an updated P/S pressure valve that would fix a "similar" issue.

OR,,,,,,does this sound like your problem,,,,,

"Some customers may comment on a lack of steering assist when stopped or during parking lot type maneuvers. A lack of steering assist could occur if the brakes are applied and turning the steering wheel with the vehicle stopped or during parking lot type maneuvers. This condition will go away or greatly improve once vehicle begins to move or is above parking lot speeds. This concern can be aggravated by worn tires, low tire air pressure, low power steering pump pressures, and tires larger than stock size."

kinda but not really. Now that I think about it I have noticed this while my foot was on the brake, but it is definitely only noticeable while say pulling in, or backing out of a parking space.

Tires are worn, however definitely properly inflated. I am running stock tires, so they aren't oversized.

Now I will focus on attempting to make this happen WITHOUT my foot on the brake. Even if I am pushing on the brake, I should think that this SHOULDN'T happen though...?

Thanks for your information!

[madmatt]

normally you would notice only slightly harder steering effort while braking but shouldn't be considered "difficult" ever.

[Stlheadake]

This is really just enough to be a nuisance. I just wish I could either replicate it at will, or just make it go away.

[dually2002]

I don't think that the current grade of P/S fluid is adiquate for the application of our trucks. Changed fluid and added Lucas P/S additive about a year ago mainly to stop serious seepage from my hydra boost package which it did, also gave a more solid feeling when turning the wheel. Don't know what the change intervials are on the fluid but it takes a beating and there is no filter that I know off.

[Stlheadake]

That's interesting....I never really considered that. My truck only has 40K on the clock, but maybe a change is needed. I just know my friend and I have almost identical mileage, and nearly identical trucks with the same weird problem.

I wondered if anyone else is having this, but apparently they aren't. How did you go about flushing the old oil out of the system?

[DmaxMaverick]

That's interesting....I never really considered that. My truck only has 40K on the clock, but maybe a change is needed. I just know my friend and I have almost identical mileage, and nearly identical trucks with the same weird problem.

I wondered if anyone else is having this, but apparently they aren't. How did you go about flushing the old oil out of the system?

Changing/flushing the fluid is a recommended practice. It helps the situation, and is VERY easy to do. The choice of fluid is also key. You could use the "recommended" PS fluid, or like me, use synthetic ATF instead. I've found, over the years, it lasts longer and changes in performance varies less with temp swings. Over time, I have discovered longer periods before leaks and/or failures. Adding a cooler is also beneficial, but not a profound improvement. If you are operating at/near the extremes, fade is less with cooler fluid. During winter, the fluid can be too cool, making the system sluggish, so some consideration for this is necessary.

Unlike most folks here, I've been driving GM trucks with this system for about 25 years. Most people either didn't know they had it before, or are just now getting familiar with it. During this time, I've gotten used to its quirks, and find myself anticipating it. I do a LOT of steep, windy mountain road driving, empty and loaded to the gills, so braking/steering is not an incidental thing. This system, despite its quirks, is very reliable and effective. It has remained essentially unchanged for over 25 years.

Fluid change/flush:
Disconnect the low pressure hose at the hydroboost unit. Do not disconnect at the reservoir, or it will be very messy. It will be the one with the spring clamp (upper/outboard), not the threaded tube fittings. This is the return line. Install a hose onto the barb, long enough to reach over the fender and to a container or tub (secure the end by inserting it into a container a few inches, or to the edge of the tub--it may jump around with fluid flow). Idle engine and turn the steering wheel L/R (about 1/4 turn, just enough to create a demand) until the fluid pumps out, and the steering no longer responds. Turn off engine. Fill the reservoir and repeat, but also pump the brakes with steering input. Repeat this 3-4 times, or until all the old fluid is pumped out, and there's no indication of old fluid coming out of the return line (should be a significant color change). It will take 1 - 2 gallons of fluid for a complete flush/fill. Reconnect the return line and fill the reservoir to the "Full-Hot" mark. Idle the engine, pump the brakes to the floor a couple times, and turn the steering from lock to lock a few times. This will bleed most of the system. Fill the fluid level to the "Full-Hot" mark. The system is self-bleeding, and does not require any bleeding efforts. Check the level again after some driving. Done. The whole process should take less than 30 minutes, if you take your time.

[mattb5150]

Does anyone have the part number for PRV valve?

Matt

[DIESEL5]

I have the same problem with my 06' D Max and your right its just enough to annoy ya Mine is still under warranty though so i dont want to push my luck with changing to a differnt fluid! I do have 285's on mine so i am glad to know that its not just because of the tires

[03silverchevy]

164k on my duramax and I've experienced the loss of p/s when parking in a lot. I am also experiencing fluid loss at the hose and the hydroboost unit. When replaced will flush system and recheck. I'll repost after the change.

[mattb5150]

madmatt, looks as if you are quoting a TSB can you post the TSB number? The local dealer can't find anything about a PRV valve problem.

Thanks,
Matt

[madmatt]

Does anyone have the part number for PRV valve?

Matt

ask and ye shall recieve!!!!!!!
"#PIT3386D: Lack of Steering Assist or Shudder During Parking Lot Type Manuevers (Jul 31, 2006) "
and another excert from that bulletin,,,
"In some cases, where the power steering pump pressures are at the low end of the specification, replacing the power steering flow control valve with P/N 26095470 may improve the concern."