Picked up an 09 M1123 and the power steering is wonky

[sp00n]

Curious does the steering act the same in both directions? how about the brakes.
There is a special tool kit for the HMMWV that does not cost TOO much it has a test gauge setup to test the PS pump flow and pressure among many other handy tools to have.

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It is interesting that so many have so much trouble with the steering pump/gear on the HMMWV, it is the same setup used for decades on civilian cars and light trucks and I have seen very few of those issues in all the years I have twisted wrenches.

When I put the GEP in the Detroit it whined for a little while like all PS units do when air is introduced but after a while it stopped like they usually do.
I just wonder what makes a HMMWV think it is so different...

In fact the systems are so similar that I used the PS test gauge on my 2008 Dmax one ton, after 300,000 as I suspected the pump is rather week, this accounts for the sluggish steering and the additional pressure required on the brake pedal.

Brakes are very firm and extremely sensitive just like all the HMMWVs I've ever driven on post. Steering has a pronounced pulse of easy/moderate force required to turn the steering wheel in both directions both stopped and at speed. I may just replace the pump for insurance since it's integral to the brakes as well, it's unusual that it isn't whining but definitely feels like it's failing. The steering itself doesn't have any dead zones or mechanical slop so I don't believe the steering gearbox is the culprit here..

 

[TNDRIVER]

Brakes are very firm and extremely sensitive just like all the HMMWVs I've ever driven on post. Steering has a pronounced pulse of easy/moderate force required to turn the steering wheel in both directions both stopped and at speed. I may just replace the pump for insurance since it's integral to the brakes as well, it's unusual that it isn't whining but definitely feels like it's failing. The steering itself doesn't have any dead zones or mechanical slop so I don't believe the steering gearbox is the culprit here..

On the first stop the accumulator on the brakes may be hiding a bad PS pump........Just my 2 cents

 

[Mogman]

On the first stop the accumulator on the brakes may be hiding a bad PS pump........Just my 2 cents

I am just curious how the "bad pump" charges the accumulator to begin with? pumps generally make pressure/flow or they don't. also how does the pump know when he gets to the same point in the steering every time so it knows to quit?

 

[TNDRIVER]

I am just curious how the "bad pump" charges the accumulator to begin with? pumps generally make pressure/flow or they don't. also how does the pump know when he gets to the same point in the steering every time so it knows to quit?

Bad, broken vane in the pump "might" cause the pump to "pulse" or a bad worm gear or ball in the steering box. The pump is obviously making some pressure to operate the brakes . Multiple , quick applications of the brakes to exhaust the accumulator "might" reveal a bad pump if one know what to look for. If the steering is "only" acting up 1/4 turn off center with no other issues, bad steering box. Air in the system is across the entire sweep of the steering. Also the belt could be slipping without any noise to clue one to this problem but would probably manifest itself at other places in the steering not just 1/4 turn. Sick HMMWV= can of worms. These things are not for the "not mechanically inclined types" Just my 2 cents

 

[badger_610889]

Curious does the steering act the same in both directions? how about the brakes.
There is a special tool kit for the HMMWV that does not cost TOO much it has a test gauge setup to test the PS pump flow and pressure among many other handy tools to have.

NEW IN BOX Kippertool 57K0267 Vehicular Tool Kit - HMMWV HUMVEE 5180-01-387-5455 | eBay

Find many great new & used options and get the best deals for NEW IN BOX Kippertool 57K0267 Vehicular Tool Kit - HMMWV HUMVEE 5180-01-387-5455 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

It is interesting that so many have so much trouble with the steering pump/gear on the HMMWV, it is the same setup used for decades on civilian cars and light trucks and I have seen very few of those issues in all the years I have twisted wrenches.

When I put the GEP in the Detroit it whined for a little while like all PS units do when air is introduced but after a while it stopped like they usually do.
I just wonder what makes a HMMWV think it is so different...

In fact the systems are so similar that I used the PS test gauge on my 2008 Dmax one ton, after 300,000 as I suspected the pump is rather week, this accounts for the sluggish steering and the additional pressure required on the brake pedal.

My guess (I could be wrong) is that hmmwv's have a very neutral front setup therefore a lot of efforts go on the steering mechanism to get the wheels back straight compared to civilian cars and trucks where wheels come back more naturally, especially in North America where cars and light trucks are setup to understeer.

Some other performance vehicles (Ferrari is an example) have steering failures mostly the assistance loss but sometimes even broken steering rods, the front end takes a lot of stress.
Keep opening the front train and stress goes up with the front that wants to dive left and right and the steering takes a lot of high variations that will stress the steering assistance.

One guy I worked with recently was telling that during his time at Porsche they have been retaining the McPherson system on the 911 (while it's a bitch to setup for track) for multiple reasons including that it distributes stress very nicely compared to the double A arm setup. I heard they have now A arms for a race version only of the 911.

I had similar experience with the equivalent of Baja racing in Europe to a point that we compromised camber and castor angles to stop braking steering rods and we changed pumps and racks annually otherwise they would fail randomly.

This may not be actually related but I see some correlation there... my two cents

 

[juanprado]

Since you have a thermal fan, someone has tinkered with it using civy parts. The Integral reservoir pump is a standard GM Saginaw design but the hmmwv uses a specific to it only higher pressure pump due to the hydraulic fan clutch not used on Gm, Hummer, or civy models and some trucks can be equipped with hydraulic mile marker front or rear winches. The cores for these higher pressure pumps are in demand and not readily available. I suspect you have a civy regular pressure hydroboost pump that can be causing issues or as noted by others, oe pump is on the way to retirement....

YMMV

 

[mgFray]

Since you have a thermal fan, someone has tinkered with it using civy parts. The Integral reservoir pump is a standard GM Saginaw design but the hmmwv uses a specific to it only higher pressure pump due to the hydraulic fan clutch not used on Gm, Hummer, or civy models and some trucks can be equipped with hydraulic mile marker front or rear winches. The cores for these higher pressure pumps are in demand and not readily available. I suspect you have a civy regular pressure hydroboost pump that can be causing issues or as noted by others, oe pump is on the way to retirement....

Any idea if the core is _really_ different then the CIV pump? Or is it just a higher tension bi-pass spring to keep the pressure up. (I'm assuming it would be different if it's higher pressure AND higher flow then a standard one.)

 

[Mogman]

Since you have a thermal fan, someone has tinkered with it using civy parts. The Integral reservoir pump is a standard GM Saginaw design but the hmmwv uses a specific to it only higher pressure pump due to the hydraulic fan clutch not used on Gm, Hummer, or civy models and some trucks can be equipped with hydraulic mile marker front or rear winches. The cores for these higher pressure pumps are in demand and not readily available. I suspect you have a civy regular pressure hydroboost pump that can be causing issues or as noted by others, oe pump is on the way to retirement....

YMMV

The "civy" pump (metric Saginaw P series) is the same the only difference is the pressure relief valve, I used a rebuilt (Cardone) one for 3 years on the Detroit before going to the remote type when re-powered with the GEP turbo.
The only thing I did was use the pressure/flow tune up kit available, OR just use the output fitting from your original pump, I also have a 12K hydraulic winch and it worked perfectly, in fact the remote pump on the GEP is the higher pressure type and I honestly cannot tell any difference, the pump only makes max pressure when the steering is at lock or against a rock.
If it were me I would drive it a little and see what happens as your problem does not sound like a pump issue if it turns OK to the same point every time, that sounds like a steering gear/valve issue. OR borrow a test gauge and actually test your pump before starting to "parts swap"
I did test the "civy" pump and it made specs.

 

[Mainsail]

Some years back I had a mid 80s Ford Courier truck as my daily driver. I bought it from my neighbor. The steering had a peculiarity in that after the turn the steering system didn't center itself, so if you let go of the steering wheel the truck would keep turning. I couldn't figure out what the problem was, but it irritated me.

One day, and I wasn't having a very good day, I was trying to get turned around in the flying squadron parking lot. The steering requiring effort in both directions for a 5-point K-turn amped up my rage level, and I jerked the steering wheel hard over. Then I heard a magical POP and the steering was suddenly very easy, but didn't feel right....

My forensics investigation revealed I had broken the idler arm at the pivot. Being broken open I could see the sealed unit had no grease whatsoever, and was pretty rusty inside. I'm guessing Ford forgot the grease in this one.

So all to say, if it's not the power steering it might be one of the pivot points in the steering assembly has a problem - like a rough spot or nick - that's catching as you turn.

I take it you've jacked it up and turned the steering full lock to full lock using one of the wheels? If not, try that and feel if there's any roughness at any point in the travel.

Of course, I may be way off if I'm not understanding what the problem is.

EDIT to add: How much have you driven it? I ask because my Yermo 1165 did that at first too, then as I drove it a few more times it seems to have gone away.

 

[REF]

If it goes 1/4 turn and get tight then back to normal ? have you checked the u joints in the steering shaft ? May have a dry u-joint binding.

 

[juanprado]

Any idea if the core is _really_ different then the CIV pump? Or is it just a higher tension bi-pass spring to keep the pressure up. (I'm assuming it would be different if it's higher pressure AND higher flow then a standard one.)

The physical case of the pump housing and reservoir is the same. The internals are different. One of the items different is the piston as they can be different pressure. Not sure on the valve. I know there is aftermarket valves to lower pressure for the hot rodders out there using rack and pinions instead of saginaw gear boxes. Using a pressure tester is a good idea. Old school power steering rebuilders could check/test but like radiator shops is a dying breed. They will not typically have the higher pressure rebuild kits but just basic reseal parts.

Another thought would be to drain and change the fluid. Is bright red for Derxron ATF or is it yellow like power steering fluid?

 

[Mogman]

The entire tool kit I listed above is only $300 with shipping and there are a ton of handy tools besides the pump test kit from changing ball joints/tie rods to replacing seals and bearings and much more, comes with a rivet/rivnut tool, it even has a run flat remover,,, well worth every penny for anyone with a HMMWV IMHO.

ONE thing though if you use the test kit for the steering pump it says IIRC to press the brake pedal as hard as you can, just press it hard enough to make specs, I ended up having to replace the piston seal in the Hydro-Boost, but it was 30 years old so it could have been on the way out anyway.

The needle will not be real steady as you will be bumping the relief valve but it will give a pretty clear indication of the pump condition.

I tend to agree with Mainsail use it for a while and see if it starts to work correctly, most HMMWVs coming out now do not have enough miles on them to have a worn out pump but the valves in the steering gear and other steering components can be gummed up.

The Saginaw P series is a vane pump it does not have a piston, the one for the HMMWV would be the metric/w 3/4" press on pulley, I just bought the pump and re-used the reservoir and pulley

 

[TNDRIVER]

2009 M1123 6.5 NA 4L80E in very good running condition. No leaks, none. Zero

The only problem I'm having with it is the power steering feels very much like it has air in the system/low on fluid- however the black lunar lander fluid reservoir typically near the fuel filter on the top of the engine is..just not there. There are no plugged lines, no leaks, and the lines to the steering box are hooked up. Truck definitely has *some* power steering as you can turn the wheel with one finger, but it makes about a quarter turn and then increases resistance then goes back to easy, in a pulsing pattern while you turn the wheel. Exactly like it's got air in it. The pump seems to be present under the 200a alternator, following the hoses did not reveal any reservoir to add/check fluid. Perhaps they updated the system and it's buried somewhere less than obvious? All the 2016+ trucks I have access to at work have the black reservoir right on top.

Like I said, absolutely no leaks or plugged dangling lines. Please advise

Before worrying about the pump or steering box get an aerosol can of belt dressing, soak a small rag with the stuff and "rub" it on the exposed area of the belt. I'M GOING TO ADD HERE "DO IT WITH THE ENGINE OFF" . Wipe what you can from the top then crawl under the truck and wipe the exposed portion of the belts on the bottom, keep the rag soaked give everything you can reach(not hid on the pulley) a good wipe. Now test again. If its still acting up you have eliminated the easiest repair first. And my guess the problem. Just my 2 cents.

 

[Mogman]

He has a serpentine belt, I have never heard one of those slipping but I guess anything is possible after cooking in the California desert for decades!!

 

[Mullaney]

He has a serpentine belt, I have never heard one of those slipping but I guess anything is possible after cooking in the California desert for decades!!

.
One of the guys here has a Suzuki that we looked at today in the parking lot. It isn's a HMMWV by any stretch of the imagination, but it has a gosh awful belt squeal. Went out with a can of belt dressing. Opened the hood expecting to see a series of V-Belts. Nope, serpentine and so it got squirted... Squeal is gone until the next rain or when "the goody" wears off.

My guess is the cooked in the desert is about right for this vehicle too. Not really in the desert, more like drive it until the wheels fall of it in this guys case.


.

 

[juanprado]

rubber detoriates and they get slick on the flat side of the smooth idler and tension pulleys.

 

[TNDRIVER]

He has a serpentine belt, I have never heard one of those slipping but I guess anything is possible after cooking in the California desert for decades!!

I didn't want to try "splain'n" the tensioner yet.

 

[Mainsail]

Before worrying about the pump or steering box get an aerosol can of belt dressing, soak a small rag with the stuff and "rub" it on the exposed area of the belt. I'M GOING TO ADD HERE "DO IT WITH THE ENGINE OFF" .

Well there's no sport in that.

 

[juanprado]

Well there's no sport in that.

In the good ole days. You used a bar of soap and let the belt scrape on it while running and avoiding spinning objects..... soap actually would work for a while or until you went fording......

 

[Milcommoguy]

In the good ole days. You used a bar of soap and let the belt scrape on it while running and avoiding spinning objects..... soap actually would work for a while or until you went fording......

That a slick idea, CAMO