Power steering circuit issue

[Will L.]

There is a gal whose Dad died and left her his hummer. She is trying hard to keep it, but fighting this issue a long time and running out of cash quick on it.

Any help on diagnostics, a shop in her area of Minnesota with a real expert, out of the box thinking, etc welcome.

The system operates just like gmt400 and iirc uses same pump and brake booster. Hummers rate fluid as atf dex3 factory with p/s fluid as backup.


For those of you who don't know, I inherited my truck from my dad, and he never let me drive it! lol So I am rather unfamiliar with "normal" for these vehicles. This one has 40" tires though, so when your power steering isn't right, that does tend to stick out....

We are having a power steering issue, where, when the truck heats up, you start to lose power steering and eventually it begins to howl.

July 2015, the steering gear was replaced with the same Saginaw version that is also used in Jeeps per instructions from Breggin. Power steering pump also replaced. Steering after that was tighter, but seemed normal, if a little underpowered. Standard GM pump. No issue with overheating.

November 2016, replaced a TON pf suspension parts: all shocks, all ball joints, idler arm, pitman arm, front tie rods....and replace all power steering hoses.

I get new tires in Feb 2017...steering a little harder.

Around May, I run over a 4x4 obstacle course, and end up jamming a 1000 lb log between the front and back axles (yes the undercarriage protection was on), and carrying it all the way out of the obstacle another 60 ft or so before it falls out. At this point, I discover I have no power steering. Super fun driving the hour home.

I order a PSC pump, which the shop installs. First pump comes missing some of the lines for the breather/overflow tube (there was no tube, or valve for that matter), so we don't even make it home before it is spraying power steering fluid all over the engine compartment and back to the shop it goes.

They "fix" the problem, and I take off again. This time I make it 45 mins up the freeway before discovering that the power steering is now groaning. I still have assist, but it is weak and making a ton of noise.

Back to the shop, and they put a different PSC pump in. They drive it until it warms up, and then discover it's doing the same thing. Pressure tests on the system revealed that the hydro boost has restricted output. Hydroboost sent off to Canada for a remanufacture since no one in the US has one. Hydroboost returns, is installed, and system is "better" but still not working properly.

Mechanic says truck turns freely to the left, but seems hard turning to the right. Still lose some level of assist when it gets warm.

We also swapped the steering gearbox with another one from a second H1....no joy, same problem remains.

Truck does have a Mile Marker Winch on it. No changes made to that which I am aware of.

No obvious fluid restriction around the power steering cooler, the pump, or the hydro boost.....fluid is clear, clean, and brand new. Steering acts up the worst when the truck is warm. Noise only happens when the truck is warm....like freeway speeds for at least 20 minutes in balmy weather warm.

Ideas?? What are the next things you'd check???

We're thinking of bypassing the winch, but without that thing operating, I don't know why it would even be an issue. I haven't messed with that at all yet.

Is there a way a damaged or bent steering component would cause this? Truck tracks relatively straight and no major shaking other than normal from 40" tires.

We're all scratching our heads.
_________________
2001 H1 SoftTop

 

[Will L.]

Chop copying from Wow’s Daughter posts:
Yes, it has a cooler, sorry forgot to mention it was both pressure tested and bypassed with no problems!

It's in Fargo, ND right now if anyone is nearby! (11/2/17)

Phazer asked:
With the mile marker on the truck, I would suggest to use a higher output pump than the stock pump. Another thing that would "help" with your hard steering issue is to add a rock ram.

I believe some of your problem is the steering gear that you installed and the other is likely the pump that you installed. With the stock gear, stock pump and no mile marker I know 40s shouldn't be overly difficult on the system, the addition of the milemarker puts strain on the pump. The stock output is around 1.5 gallons / min. AGR has a pump (which I believe can be sold separately) that is around 4.5 gallons / min.

If you choose to put a rock-ram on the truck, it will include a new gear, pump, lines (to the ram) and of course the ram. They will make steering your truck a dream. Its a fairly straightforward install, but the biggest pain is bleeding the air out of the system, that takes a while.

Me:
You need to have another hummer owner drive it to see what they feel. You need to meet up with someone to drive theirs to see how it should feel.

What fluid are you using? Was an inline filter installed to catch debris from first failure? If not reverse flush the system except pump. If so is the filter plugging?

Did they pressure and flow test out the new brake booster after fluid is heated up and problem starts?

Have they run temperature tests and and comparative test on another hummer as a base line? Same for volume testing?

Have you Replaced rubber hoses? There can be a hose coming apart on the inside- that happens worse when heated and a flap of rubber creates a restriction.

Diagnostics of a hydraulic system is labor intensive- which means $$$. Thats why most just replace the parts. They are cheaper and you can do it yourself.
Inline pressure, flow meters, temp sensors, and a recording monitor- then moving the sensor to different locations in the system takes a lot of time and components.

Sometimes a simple error gets repeated- verify by another Hummer that hoses/ lines are not reversed somewhere.

I would start by bypassing the winch.
If that doesn’t show difference, keep it out of the system and bypass the brake booster so only the steering box is in use.
Having a couple hoses made at a hydraulic shop would be required.

I believe what all that would point to is a problem with the pump or box. Hopefully you would find that removing a component fixes the issue and can then be replaced.

By the time you are done, you will be the Hummer steering system expert.

Sign up on the truckstop.us and thedieselpage.com.
Copy and paste your explination from here to there, but add that the booster, pump, box,etc all is the same system as the gmt400 (1990’s) diesel pickups.

If you want I will do it on thetruckstop for you.

 

[Will L.]

Her response:
There are no other Hummer owners within 300 miles of me as far as I know, other than the poor other guy who's '98 is in the shop right next to mine - not sure if his is drivable and the shop is 2 hrs from my house...one direction. NO ONE within an hour of here will even touch that truck.

Power steering fluid, brand new PSC pump with filter. System has been completely flushed at this point....several times

Yep, the hydro boost tests fine now

The only other H1 is the 98 that's also in the shop, power steering set up on that one is not comparable.

All the hoses coming to and from the pump are brand new. I will ask him to flow test the rest.

I wish....but again....no garage and winter rolling in. Not to mention no time. This was dad's truck....I probably can't keep this thing if it continues to be this labor intensive and expensive. I don't have 20-30 hours a week to devote to chasing down continuous problems, and I lack the cash to pay someone else to do it!

 

[Will L.]

Her last post:
This one isn't a stock pump....it's the PSC with the large reservoir, which was recommended by several people on the forum here. Since it's not stock, would you still consider this a likely problem?

 

[Will L.]

OK folks, thats where the fight is currently. Hopefully someone here can see where others missed.

 

[ak diesel driver]

The power steering pump howling indicates it not getting enough return flow. Gotta be a restriction or something bypassing.

 

[WarWagon]

First and foremost when you break something "F*&^ing STOP!!!" and FIX IT or flatbed it home! Driving an hour with an unknown failure gets expensive - I assume it lost PS oil and let the pump dust the system. Every time you turn the wheel without assist it would shoot oil from the steering box into the "dry" pump and whats left of the pump would do it's best to push it through the system till it ran out again carrying the lack of oil ground up bearings/pump elements with it. Nevermind the danger you post to others with reduced brakes and loss of PS. Fire is also a risk from things run without oil or oil spraying on hot manifolds. (I have been on the repair end of this after a PS box blew a seal and it took 5 pumps and replacing everything before it was fixed. Reman pumps SUCK!)

What's the fluid look like? If it was a snow globe from the multiple PS failures the entire system is dusted. Flush and replace as necessary. The expensive things like the hydroboost, steering box, can't be flushed. Not sure on the wench. Debris from a pump failure partially plugging something? What kind of PS filter and when cut open what's it look like as in what if anything is it catching?

Does this have the hyd fan setup? Maybe the fan kicking in/out is the final straw that fails the system.

Internal hydraulic "leaks" generate heat and lots of it. This would thin out the fluid. I would suggest there could be a restriction keeping the pressure needlessly high and generating heat.

It's no so much what hasn't been rebuilt in the hydraulic circuit. It is, but, if a component is skipped it will continue to contaminate the system and you get to start over. For example was the winch, that I know nothing about, rebuilt? I assume it's got a non-flushable motor on it.

And the last point and this be the most important: going hardcore off road is expensive. Especially with a Military bottomless taxpayer pocket designed Hummer. Endless ruined tires is just the start of expenses. Treat it as a toy/hobby and it's enjoyable. As a daily driver it gets to be "not fun" when you have to fix what broke before Monday AM work.

 

[THEFERMANATOR]

What is the actual flow numbers and pressure now? Iirc the full size truck box needs 2.2 gpm flow minumum to turn correctly. I fought an older dodge truck that had multiple junkyard boxes put on it, and numerous rebuilt pumps. Put a gauge on it and found it only had 1.8 gpm of flow. Truck turned fine cold, but I believe it only turned right when hot. Ended up putting a NEW pump on it, it flowed 2.3 gpm, and truck turned great both directions.

I'm also curious why a jeep box was used and not one from a full size dodge or something. I would think the 18:1 ratio and larger piston would help out with turning. And like said above, see how much stuff is plumbed into the power steering circuit, then check to see and make sure nothing is bypassing when it shouldn't, and that everything is free flowing when it should. It wouldn't take but a SMALL restriction to take the whole system down.

 

[Will L.]

Thanks for responding guys.
@ak diesel driver : I agree, she said they did multiple flushes, and of course the parts, but cant find it yet.

@WarWagon: Hummers dont have the hmmwv hydraulic fan clutch (oh how I wish they did). Same type of crappy fanclutch on our pickups, except for some reason (mfr. Paten maybe?) the fan bolt pattern differs so they can’t just bolt in a kennedy- complete fanclutch and fan combo swap is needed and doesn’t help as much as it does in a truck from stack angle.

@THEFERMANATOR : The jeep box recommended by “Breggin”: Dave Breggin is spot on with knowing the parts on these rigs, I wouldn’t think twice if he said it is the original part source. AM General did like AMC in the 70’s- using parts from various vehicles instead of building new 1 offs. Brakes from a Jeep, steering column from Ford ltd2/escort, etc. Several parts they chose were questionable at best when far stronger and more available parts could have been used. There is a better box available now, but requires major modification to fit. Many Hummers go long life with the stock box (hope I didn’t jinx myself-haha)

To WOW’s daughter another question:
Was the ‘Jeep’ steering box new, rebuilt, or used?

 

[Will L.]

Her responses:
Will L. 95 wrote:
2 more responses from the other forum i will copy/paste. First one from “WarWagon”:
First and foremost when you break something "F*&^ing STOP!!!" and FIX IT or flatbed it home! Driving an hour with an unknown failure gets expensive - I assume it lost PS oil and let the pump dust the system. Every time you turn the wheel without assist it would shoot oil from the steering box into the "dry" pump and whats left of the pump would do it's best to push it through the system till it ran out again carrying the lack of oil ground up bearings/pump elements with it. Nevermind the danger you post to others with reduced brakes and loss of PS. Fire is also a risk from things run without oil or oil spraying on hot manifolds. (I have been on the repair end of this after a PS box blew a seal and it took 5 pumps and replacing everything before it was fixed. Reman pumps SUCK!)


I still had partial steering - truck made it home fine, system still had fluid present (pump failure was internal), and the fluid was clear and not burnt. I flatbedded it to the dealer on my deckover trailer. ALL pumps have been NEW.

Will L. 95 wrote:
What's the fluid look like? If it was a snow globe from the multiple PS failures the entire system is dusted. Flush and replace as necessary. The expensive things like the hydroboost, steering box, can't be flushed. Not sure on the wench. Debris from a pump failure partially plugging something? What kind of PS filter and when cut open what's it look like as in what if anything is it catching?


Fluid is fine. All PS parts test with good flow....mechanic is communicating directly with Breggin regarding testing procedures.

Will L. 95 wrote:
Does this have the hyd fan setup? Maybe the fan kicking in/out is the final straw that fails the system.

Fan is original.....and the fan kicking in/out does not seem to affect the problem.

Will L. 95 wrote:
Internal hydraulic "leaks" generate heat and lots of it. This would thin out the fluid. I would suggest there could be a restriction keeping the pressure needlessly high and generating heat.


We all are thinking this - the problem is locating it. Is there a common location for restriction?

Will L. 95 wrote:
It's no so much what hasn't been rebuilt in the hydraulic circuit. It is, but, if a component is skipped it will continue to contaminate the system and you get to start over. For example was the winch, that I know nothing about, rebuilt? I assume it's got a non-flushable motor on it.


Winch is not rebuilt. Only rebuilt part in the system is the Hydroboost....all the others are NEW and purchased either from Breggin or with his recommendation.

Will L. 95 wrote:
And the last point and this be the most important: going hardcore off road is expensive. Especially with a Military bottomless taxpayer pocket designed Hummer. Endless ruined tires is just the start of expenses. Treat it as a toy/hobby and it's enjoyable. As a daily driver it gets to be "not fun" when you have to fix what broke before Monday AM work.


It's not my daily driver at all. I have a brand new 2017 Ram for that. Just been 3 months in the shop, and we're all getting frustrated at this point.

 

[Will L.]

A post from Dave Breggin:
Many years ago I had a problem where the truck steered in one direction better / easier than the other. It was a minor difference,
but easily noticed. I don't know how severe the difference is on your truck.

The root problem was that the steering column was not correctly installed / aligned. The dealer mechanic (warranty) failed to
properly re-install it. When I corrected it, the problem went away and has not been back. It was something to do with the mounting
bolts under the dash.

If your problem is more severe, it could be a binding U-joint or some type of alignment problem with the steering column.

With the engine off and the front tires off the ground, is there a noticeable difference in steering effort, right to left? If so,
you have now eliminated all of the assist / boost components. Disconnecting the pitman from the centerlink would indicate or
eliminate all of the steering linkages.

 

[Will L.]

Post from me:
The mechanic should be writing down pressures, flow rate, and temperature findings before and after each component if following proper procedures. Please get that info from him/her and post it.

What was the result from the single component testing —bypass winch and brake booster, only operating steering?

A few other questions asked still unanswered, please reread & follow up.

 

[THEFERMANATOR]

Have them call redhead or blue top steering. Either of them can tell you about the steering boxes, and what can be and can't be swapped inside the housings. And make sure the system is flow and pressure checked.