Power steering issue / question

[mstepchinski]

Hello,
I have a M929A2, and the power steering while stationary has failed. I have noticed that assist does work turning to the left while stationary, but to the right it does not. Any ideas on this one? It also seems that the assist to the left only works when wheel is already turned slightly to the left and not from center. Assist does seem to work when vehicle is moving.

I had quite a scary drive Sunday while turning out of an intersection onto a major highway.

Thanks in advance.

 

[dmetalmiki]

You need to strip the box down and check the sensing valves.
"Difficult steering in one direction could point to a faulty valve in the steering gear mechanism. A malfunctioning valve will cause the steering gear fluid pressure to drop below manufacturer’s specifications. Poor fluid pressure may also be the result of a bad pump or a leaky hose, which affects fluid delivery. Poor fluid delivery will also cause the power steering to behave erratically. Other causes of hard steering in one direction is the vehicle’s front end binding due to faulty kingpins or steering linkages, air trapped in the hoses or fluid contamination."

 

[mstepchinski]

You need to strip the box down and check the sensing valves.
"Difficult steering in one direction could point to a faulty valve in the steering gear mechanism. A malfunctioning valve will cause the steering gear fluid pressure to drop below manufacturer’s specifications. Poor fluid pressure may also be the result of a bad pump or a leaky hose, which affects fluid delivery. Poor fluid delivery will also cause the power steering to behave erratically. Other causes of hard steering in one direction is the vehicle’s front end binding due to faulty kingpins or steering linkages, air trapped in the hoses or fluid contamination."

So I have a few things to check. I would like to start with bleeding the system, so I will look into the TM's I have to get a good procedure. Instead of 10w oil, do you recommend ATF / PS fluid?

 

[Scrounger]

First a couple of questions. Is the truck new to you? How many miles have you driven it without trouble? Have you worked on the power steering system lately? Does if have any power steering fluid leaks?

The best way to bleed the power steering system is to lift the front axle up enough so the front tires are clear from the ground. Jack stands are your friend. Make sure the power steering reservoir is full, then start the engine. With the engine running turn the wheels full left, pause, then full right, pause. Repeat a couple of times. If the fluid was low or if there is air in the system you may have to add fluid, so check after a couple of lock to lock turns.

If it has 10w oil in it keep it that way.

 

[mstepchinski]

First a couple of questions. Is the truck new to you? How many miles have you driven it without trouble? Have you worked on the power steering system lately? Does if have any power steering fluid leaks?

The best way to bleed the power steering system is to lift the front axle up enough so the front tires are clear from the ground. Jack stands are your friend. Make sure the power steering reservoir is full, then start the engine. With the engine running turn the wheels full left, pause, then full right, pause. Repeat a couple of times. If the fluid was low or if there is air in the system you may have to add fluid, so check after a couple of lock to lock turns.

If it has 10w oil in it keep it that way.

Hello, this truck is new to me. I drove it about 15 - 20 miles without issue. Next time I went to drive it, I noticed it was difficult to move the steering wheel at idle and stopped. I added some Dexron fluid (suggested on this forum), and all seemed fine while stopped, etc. Drove it another 15 miles or so and all was good. Looked under the hood and saw a small crack in the top rubber line and saw some fluid on both hoses, so I cut the cracked portion of the hose off and reclamped. Refilled with Dexron and all seemed ok for another drive. Finally got in Sunday and no power steering assist at idle to the right, but assist worked turning to the left. Tried working wheel back and forth with elevated idle without success. Assist finally failed altogether.

It does feel as if assist is working under speed - easier to turn the wheel than I'd imagine without assist.

Hopefully this makes sense. I was thinking about trying to drain everything, refilling with Dexron (or 10W if I should go back to that), and trying to bleed the system. Or, should I try another method?

 

[Scrounger]

The symptom described is classic air in the system and will need to be purged. What happen is “bubbles” in fluid doesn’t provide enough pressure to operate the varies components. The truck should have had 10w oil in it when it left service, that’s what the book calls for. That doesn’t mean somebody didn’t do something different. 10w and Dexron don’t get along together, so a flush is probably in order. That will require removing the low-pressure line from the power steering pump, top off the reservoir, then with the engine running turn the wheel lock to lock and collecting the old oil. Stop every so often to refill the reservoir. Once the fluid coming out is clean reinstall the low-pressure line. Then bleed the system as above. If you don’t have soldier B to hold the low-pressure line when bleeding, jerry rigging a longer line to reach a bucket will cut down on the mess.

It should go without saying, however a good look at the power steering lines would probably be a good idea.

I have always gone by the saying if it isn’t broke don’t fix it. All my trucks that came with 10w in the systems still have it.

 

[mstepchinski]

Thank you for your helpful advice. This weekend will be spent following it. I would assume the high pressure line is the one that is reinforced going into the gearbox, correct?

 

[Scrounger]

There are two lines on the power steering pump, pressure and return. You are correct about the reinforced line being the pressure line. For bleeding the return line to the pump is low pressure and usually just uses a lite duty clamp.

 

[mstepchinski]

There are two lines on the power steering pump, pressure and return. You are correct about the reinforced line being the pressure line. For bleeding the return line to the pump is low pressure and usually just uses a lite duty clamp.

Makes sense, and that is the line that had the crack in it that I clipped off. I'm looking forward to getting this issue resolved to get back on the road with my new to me 5 ton. After this, I want to dig into a CTIS issue (likely has happened to all us 5 tonners).

Appreciate the step by step. I tried to find the section of the TM that deals with steering, but it was section WP 500 and manual only went up to WP 150 or so. I'm guessing there are different sections of the TM for this unit.

Thank you again.

 

[Scrounger]

The important thing about flushing and bleeding is to have the front tires able to move freely, hence having the front axle lifted. The bleeding of air occurs when the steering is at the stops. When there is air in the system one can hear it clearing, almost as a pulse, when purging. Just make sure the reservoir never goes dry, or you have to start over.

 

[mstepchinski]

The important thing about flushing and bleeding is to have the front tires able to move freely, hence having the front axle lifted. The bleeding of air occurs when the steering is at the stops. When there is air in the system one can hear it clearing, almost as a pulse, when purging. Just make sure the reservoir never goes dry, or you have to start over.

OK, I'm assuming bleeding is to be done while engine is running supplying pressure to the system. I guess I will let all the old mix of Dexron and 10W go into a waste bucket and keep filling the reservoir with 10W. I heard Tractor Supply is a good place to get 10W (hydraulic fluid?)

 

[Scrounger]

OK, I'm assuming bleeding is to be done while engine is running supplying pressure to the system. I guess I will let all the old mix of Dexron and 10W go into a waste bucket and keep filling the reservoir with 10W. I heard Tractor Supply is a good place to get 10W (hydraulic fluid?)

Yes, the engine must be running. Basically, disconnect the return line and run it to a catch container, five-gallon pail, gallon jug, you get the idea. Fill the reservoir turn the steering lock to lock, check the fluid level. Turn lock to lock, check fluid. Keep repeating till clean oil.
Around our area NAPA carries 10w oil. It is AW32 five-gallon pails part number NHF 85905.

 

[mstepchinski]

Yes, the engine must be running. Basically, disconnect the return line and run it to a catch container, five-gallon pail, gallon jug, you get the idea. Fill the reservoir turn the steering lock to lock, check the fluid level. Turn lock to lock, check fluid. Keep repeating till clean oil.
Around our area NAPA carries 10w oil. It is AW32 five-gallon pails part number NHF 85905.

Thanks. Will grab from NAPA tomorrow provided it's in stock. Appreciate your responsiveness towards my issue. Will let you know how it all goes.

 

[LCA078]

mstepchinski- i'm in oak hill (SW part of Austin) and recently picked up a M923. So if you need a Soldier B, let me know and I'll try to come out and wrench with ya.

Also, I'm jealous of the real dump- i'm thinking of adding a dump feature to my M923 just to haul stuff here/there.

 

[mstepchinski]

Hello, nice to know a fellow 5 tonner is close by! I will likely try to bleed the system out today as NAPA is delivering a 5 gal jug of 10W this morning. How long have you had your 5 ton?

 

[LCA078]

How long have you had your 5 ton?

Two weeks...and it's still in San Antonio!!!

I'm still learning about these trucks, but I know my way around a wrench and machine shop. Happy to help as possible. By the way, we have some land in northern hays county (off Hamilton Pool) which is why i bought my truck. The wife doesn't understand why I need a 6x6 truck to drive around a few acres and yank out the random cedar tree so happy to have another 5-tonner in the local area too.

 

[mstepchinski]

Two weeks...and it's still in San Antonio!!!

I'm still learning about these trucks, but I know my way around a wrench and machine shop. Happy to help as possible. By the way, we have some land in northern hays county (off Hamilton Pool) which is why i bought my truck. The wife doesn't understand why I need a 6x6 truck to drive around a few acres and yank out the random cedar tree so happy to have another 5-tonner in the local area too.

Are you waiting for the clearance to remove?

 

[LCA078]

It's just sitting at my dad's shop in SA, which is about 10 miles from where I bought it. I plan to do some work on it and it's much easier to do it at the shop where we a forklift, overhead crane, various lathes, mills, etc. My house in Oak Hill is a a regular residential house so working on a 5-ton in the driveway without heavy tools isn't really the optimal solution. I'll bring my M923 to Dripping Springs within a couple months...

 

[mstepchinski]

Oh, I see. The release wait took 2.5 months for me. I'd like to see your 5 ton when you get it out this way. I'm trying to work in a full fluid and filter change this weekend if weather cooperates.