M1031 Steering noise

[dkdiesel]

From what I can figure the truck was repowered with a 6.2 out of an HMMWV at some point because it has a serpentine belt setup, HMMWV power steering pump with remote reservoir, CC rotation water pump, and HMMWV generator. The fan appeared to be an HMMWV unit with a billet aluminum adapter to eliminate the hydraulic unit that came on the HMMWV. I took that off and machined a new aluminum adapter and switched over to a viscous fan from a 6.5 TD and a fan from a Duramax. No more Fan screaming at all times. The only issue I am now having is the power steering pump is loud as hell in the cab while your driving. They had the HMWWV reservoir mounted on the driver's inner fender which I relocated to directly above the pump as I thought the pump was cavitating due to the long 3/4" hose from the reservoir to the pump. Now It's a straight shot into the top of the pump. I replaced all the power steering lines/hoses and resealed the entire steering gear. You cant hear the whine outside the truck but inside it's really obnoxious. Has anyone driven an HMWWV with the remote reservoir style pump and noticed a pump whine inside the cab? I attached a pic of the pump showing what it looks like. I have bled and bled and bled the system, pulled a vacuum on the system multiple times, etc... The fluid isn't getting aerated even after a long drive at high rpm. The steering and the power brakes work flawlessly it's just loud in the cab. I'm pulling my hair out on this and I'm about ready to pull this motor and swap a 12v cummins into it with a 4 speed trans!

 

[Skinny]

What's in it for PS fluid?

 

[dkdiesel]

ATF

 

[NDT]

Is the pump shot? Cummins swap won't fix that.

 

[dkdiesel]

I installed a flow/pressure meter on it and it made 1300 psi and was between 3.5-4 gpm. That doesn’t mean it won’t make noise but usually steering pump noise = aerated oil which it doesn’t have. One finger steering lock to lock at an idle on concrete. Only issue is noise in cab. If it is the pump yes a Cummins swap will eliminate it cause I would run the dodge steering pump that’s currently on the Cummins

hesitant to buy a new pump and have it make the same noise hence why I was asking if anyone was familiar with the hmmwv’s that use that pump.

 

[NDT]

Hmm my HMMWV has that pump and it makes no noise. Lots of times these HMMWV engines were pulled from trucks in a very careless manner. Pump may have ingested big dirt.

 

[dkdiesel]

That’s exactly what I wanted to hear! Thanks for the info. I’ll order a pump and maybe the 6.2 can stay a little longer.

 

[WWRD99]

From what I can figure the truck was repowered with a 6.2 out of an HMMWV at some point because it has a serpentine belt setup, HMMWV power steering pump with remote reservoir, CC rotation water pump, and HMMWV generator. The fan appeared to be an HMMWV unit with a billet aluminum adapter to eliminate the hydraulic unit that came on the HMMWV. I took that off and machined a new aluminum adapter and switched over to a viscous fan from a 6.5 TD and a fan from a Duramax. No more Fan screaming at all times. The only issue I am now having is the power steering pump is loud as hell in the cab while your driving. They had the HMWWV reservoir mounted on the driver's inner fender which I relocated to directly above the pump as I thought the pump was cavitating due to the long 3/4" hose from the reservoir to the pump. Now It's a straight shot into the top of the pump. I replaced all the power steering lines/hoses and resealed the entire steering gear. You cant hear the whine outside the truck but inside it's really obnoxious. Has anyone driven an HMWWV with the remote reservoir style pump and noticed a pump whine inside the cab? I attached a pic of the pump showing what it looks like. I have bled and bled and bled the system, pulled a vacuum on the system multiple times, etc... The fluid isn't getting aerated even after a long drive at high rpm. The steering and the power brakes work flawlessly it's just loud in the cab. I'm pulling my hair out on this and I'm about ready to pull this motor and swap a 12v cummins into it with a 4 speed trans!

That's a nice setup!! I wanted to ask if you have done the 3 foot screwdriver to the ear sound check on the 5 idle pulleys on this engine...that ac clutch one is magnificent...great way to keep the stock belt routing...just throwing that out there just to make sure it's not one of them vs the pump...I've missed one of those airplane whiners from the inside that was a bearing but sounded like a pump...went up and down with rpm.

 

[dkdiesel]

Yep have put a stethoscope on everything. It’s 100% the pump causing the noise. Odd thing is you cannot hear it without the scope outside the cab. The hydraboost is transferring the noise into the cab sheet metal. I could bypass the hydraboost and I’m sure the noise in the cab would be gone but that’s not a permanent fix. A new pump is anywhere from $275-$600+ But I guess I’ll have to toss one on it and see.

 

[nyoffroad]

Yep have put a stethoscope on everything. It’s 100% the pump causing the noise. Odd thing is you cannot hear it without the scope outside the cab. The hydraboost is transferring the noise into the cab sheet metal. I could bypass the hydraboost and I’m sure the noise in the cab would be gone but that’s not a permanent fix. A new pump is anywhere from $275-$600+ But I guess I’ll have to toss one on it and see.

Totally unfamiliar with your set up so just tossing this out there, is the pump/reservoir mounted with rubber mounts? Ifso are any worn or bent? I know it's a long shot but $600 a pretty big chunk. Good luck.

 

[WWRD99]

Yep have put a stethoscope on everything. It’s 100% the pump causing the noise. Odd thing is you cannot hear it without the scope outside the cab. The hydraboost is transferring the noise into the cab sheet metal. I could bypass the hydraboost and I’m sure the noise in the cab would be gone but that’s not a permanent fix. A new pump is anywhere from $275-$600+ But I guess I’ll have to toss one on it and see.

That does make sense...just hoping it could be something cheaper!! It would take some brake lines to put the 2 lines going to the hydro boost to bypass it to see if the noise goes away...I'd be curious if a valve in the boost is vibrating or pressure relief spring is weak or broken in it...the power steering pump has that spring and pressure relief valve...wonder if it is just the spring or valve going crazy in there fluctuating pressure...if you can't hear it outside and only inside I'd bet it's not a vane since those are loud as heck...the gauge reading of 1300 psi should show some type of movement though if it was a valve or spring...tough one...any chance it has a vacuum tip on top of the reservoir to stick a vacuum pump on to suck out the air bubbles? Like the old whiney Fords/chrysler? Can you make a cap to try the vacuum on the fluid? IDK I feel like I'd try the kitchen sink next!
So I thought a little more and remembered my Honda days in the early 90s that had issues with the PS reservoir having a screen in it that would get clogged up and slightly starve the pump of fresh fluid...the fancy flush machine and fluids did nothing so replacing it was all we could do at the time...I can't tell if you have the stock plastic black PS res the HMMV has but I know they have a screen style filter in them that can get clogged up some...wonder if that's where the problem is.

 

[dkdiesel]

That does make sense...just hoping it could be something cheaper!! It would take some brake lines to put the 2 lines going to the hydro boost to bypass it to see if the noise goes away...I'd be curious if a valve in the boost is vibrating or pressure relief spring is weak or broken in it...the power steering pump has that spring and pressure relief valve...wonder if it is just the spring or valve going crazy in there fluctuating pressure...if you can't hear it outside and only inside I'd bet it's not a vane since those are loud as heck...the gauge reading of 1300 psi should show some type of movement though if it was a valve or spring...tough one...any chance it has a vacuum tip on top of the reservoir to stick a vacuum pump on to suck out the air bubbles? Like the old whiney Fords/chrysler? Can you make a cap to try the vacuum on the fluid? IDK I feel like I'd try the kitchen sink next!
So I thought a little more and remembered my Honda days in the early 90s that had issues with the PS reservoir having a screen in it that would get clogged up and slightly starve the pump of fresh fluid...the fancy flush machine and fluids did nothing so replacing it was all we could do at the time...I can't tell if you have the stock plastic black PS res the HMMV has but I know they have a screen style filter in them that can get clogged up some...wonder if that's where the problem is.

The reservoir is circled in red in this pic. I have pulled a vacuum on the reservoir with the engine running and engine off multiple times no change. The pic shows the old location of the reservoir. The large rubber line that I drew the red line on was the pump feed line when I got the truck. I relocated the reservoir to where the blue circle in the pic is. I have it bolted to a bracket and its a short straight shot directly into the pump. I have tried isolating the reservoir so it wasn't touching anything and just floating there, no change. I have also isolated all of the steering lines to make sure they weren't transfering noise into the body. The reservoir has a replaceable filter inside of it, I installed a new one. The odd thing is there is no air in the system. I have put 250 miles on it since relocating the reservoir, replacing all of the lines etc... the level has never changed since I got it bled out. I can drive it on the freeway screaming for 30 min, pull over and pop the top off the reservoir and the fluid is nice a clear.

I have found that even with the 35's at 60 mph I am getting about 12 mpg hand calculated... I'm thinking I'm gonna let the pump scream while I get a 12v cummins put together and a 4 speed 47rh built and get rid of the 6.2/th400. It's sad because the motor has less than 11k on it and it runs like a top. But I know I can pull 17-18 mpg out of a 12v and easily have 400 hp at the tires. Engine and transmission my be up for sale in classifieds soon.

 

[WWRD99]

The reservoir is circled in red in this pic. I have pulled a vacuum on the reservoir with the engine running and engine off multiple times no change. The pic shows the old location of the reservoir. The large rubber line that I drew the red line on was the pump feed line when I got the truck. I relocated the reservoir to where the blue circle in the pic is. I have it bolted to a bracket and its a short straight shot directly into the pump. I have tried isolating the reservoir so it wasn't touching anything and just floating there, no change. I have also isolated all of the steering lines to make sure they weren't transfering noise into the body. The reservoir has a replaceable filter inside of it, I installed a new one. The odd thing is there is no air in the system. I have put 250 miles on it since relocating the reservoir, replacing all of the lines etc... the level has never changed since I got it bled out. I can drive it on the freeway screaming for 30 min, pull over and pop the top off the reservoir and the fluid is nice a clear.

I have found that even with the 35's at 60 mph I am getting about 12 mpg hand calculated... I'm thinking I'm gonna let the pump scream while I get a 12v cummins put together and a 4 speed 47rh built and get rid of the 6.2/th400. It's sad because the motor has less than 11k on it and it runs like a top. But I know I can pull 17-18 mpg out of a 12v and easily have 400 hp at the tires. Engine and transmission my be up for sale in classifieds soon.

Well, I think I've exhausted what I'd look for before I'd replace a part...be nice to at least see some change in it when you try something just to give some verification...well...wish you weren't on the other side of the country...I'd buy that setup all day!

 

[Keith_J]

Have you tried removing the drive belt and rotating the pump by hand? Could be a stuck vane or worn bearing.

12 MPG at a mile a minute is about right for 35" tires. I doubt a 6BT would do better than 15 without axle swap even with a .75 overdrive.

 

[dkdiesel]

Have you tried removing the drive belt and rotating the pump by hand? Could be a stuck vane or worn bearing.

12 MPG at a mile a minute is about right for 35" tires. I doubt a 6BT would do better than 15 without axle swap even with a .75 overdrive.

Yes I have run the pump on the bench with a drill motor returning back to the reservoir just to verify it wasn’t aerating the fluid. After I verified it wasn’t aerating on the bench I ran the pump with a drill on the truck as well. Drill didn’t have enough power to spin it fast enough to make the whine. The pump is smooth.

even if a Cummins only gets 15 mpg I will get everywhere much quicker! And be able to actually tow something at speed.