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  #16  
Old January 9th, 2021, 18:56
techno1154's Avatar
techno1154 techno1154 is offline
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Re: Power steering cooler and cavitation during winter

Is the top of the radiator/AW4 oil cooler higher than the steering reservoir oil level? Make sure it is.
The reservoir need to be vented and higher than every thing else in the steering system including the hoses. My XJ had the same problem with cavitation some time ago, that led me to pull the cap apart. Cavitation tell tail is the presence of air bubbles in the oil during and after the engine have been run in addition the noise the pump vanes make when they are starved for oil.
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1996 XJ; 4.0L; AW4; NP231; SYE; D30 and D44; ECTED; 4.10 gears; 30X9.5 -15 BFG/AT/KO; 3" lift; Rusty's LCA; JKS ADJ UCA; Kevins ADJ Track bar; Drawtite Front Receiver; Dual Electric Fans; Dual Battaries.
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  #17  
Old January 9th, 2021, 19:14
Black1990jeep Black1990jeep is offline
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Re: Power steering cooler and cavitation during winter

Quote:
Originally Posted by lordoeuf View Post
I have the Lee Power Steering pump, which includes an aluminum reservoir with a Lee cap. From what I can tell, there isn't any venting on the cap or the reservoir. When I open the cap, I can hear a sound like the release of pressure, sort of like when you open a soda pop bottle. So the air is definitely pressurised in there and not at ATM.

After driving the car with a stock pump/reservoir, do you not hear that "pop" when you remove the cap? On the Lee pump, if I turn the wheels lock to lock a few times then remove the cap, I hear a "pop".
Stock reservoir is vented, yours should more than likely also be vented even though it is non stock. The fluid expands when heated, it gets hot, it has to have a vent the air above the fluid as that air space gets smaller as the fluid expands into that space. Set your cap loose and try driving and see if problem noise goes away or not. Now maybe the lack of vent is not the cause of the problem, but even so it should be vented. So assure you have a vented cap I have a VW with power steering, and its cap IS vented too.

My vented cap never makes a pop noise on my XJ.

You may have air in system still, which oft makes the gurgling noise, so once you got the cap vented, perform the air purging procedure, turning lock to lock many times as reservoir is observed for bubbles. Once the bubbles stop forming, then it is purged of air. A leak in the hose, or reservoir or elsewhere can allow air to enter during use. make sure hose fittings are tight. air in the system is not only noisy, it can be destructive
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  #18  
Old January 9th, 2021, 19:23
lordoeuf lordoeuf is offline
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Re: Power steering cooler and cavitation during winter

Sorry, but I don't quite follow your question. The transmission oil cooler, which is being used as the power steering cooler, is mounted in the factory location. Whatever level that stock placement is, is where the radiator is. You are asking if the top of this stock trans. radiator is at a higher elevation than the power steering reservoir level. If not, make sure it is. But then your next line says to make sure the reservoir is higher than everything else in the system. This looks like a contradiction. Could you please clarify? The reservoir is the power steering component with the highest elevation.

I don't see any sign of a vent in the Lee Power Steering reservoir cap. This is what the Lee pump and reservoir look like: https://leepowersteering.com/collect...e-xj-1987-2001

In the description on the Lee website, it says the pump/reservoir "includes our Zero Cavitation reservoir with pressurized no leak cap that is perfect for aggressive wheeling." So it sounds to me like the reservoir is NOT supposed to be vented. Apparently the reservoir has some special flow design which is supposed to make it not cavitate. How well that works, I don't know.
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  #19  
Old January 10th, 2021, 02:25
lordoeuf lordoeuf is offline
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Re: Power steering cooler and cavitation during winter

With the engine off and front tyres off the ground, turning the wheel lock to lock, there are tiny air bubbles in the reservoir. They are impossible to see unless I shine a focused beam of light into the reservoir. Diameters arel less than 1 mm.

Over the course of the past few days, I've turned the wheel back and forth at least two hundred times, but no matter how many times I turn it, the tiny bubbles still show up. The harder and faster the wheel is turned, the more bubbles appear, that is, as opposed to turning the wheel the same number of revolutions, but slowly. This indicates to me that perhaps air is getting pulled in through some fitting or seal. As I don't see any leaks, finding this fitting won't be easy. I've already tightened up all the hose clamps.

Unfortunately, there are so many darn seals that lead to the outside on a power steering system.

Gear Box:
Steering wheel shaft seal
Pitman shaft seal
Pitman top cap seal
Adjuster screw seal (RTV in my case)
Bore cap seal
O-rings on line in/out

Connections:
hose clamp on radiator in
hose clamp on radiator out
hose clamp on reservoir
hose clamp on low pressure pipe
factory crimps on high pressure pipe to rubber hose
high pressure connection at pump

Without a drip forming at any of these, I'm at a loss. There is some very fine mist-like residue around the gear box-in/out fittings and on the forward side of the pitman cap. It does take several days of driving for this fine mist residue to show up, so I'm not entirely sure if it is moisture or power steering fluid.

However I had gear boxes dripping puddles without having this steering issue, so I cannot really understand the current problem. My guess is that as the vehicle cools, air gets into the system through one of the seals or fittings. As the car warms up, the pressure build-up prevents air from getting in through these fittings. It takes a few minutes of driving to purge these air bubbles, so it works fine after a few minutes. Why air gets in while turning the wheel with the car off and cold - pushing all that fluid through these long radiator hoses must be creating some brief negative pressure at a fitting, thus air is forced in.

Black1990Jeep: the only way I can drive the car with the "cap loose" for this particular design is to remove the rubber washer/seal from the cap. I'll give it a go like this and report back.
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  #20  
Old January 10th, 2021, 18:19
Agreen Agreen is offline
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Re: Power steering cooler and cavitation during winter

1) the trans cooler inside the radiator is a tube that's flat and can cause restriction so that could be an issue. Power steering pressure is higher than transmission line pressure.
2) if you have the cooler hooked up backwards it will definitely cause cavitation. If you have it plumbed to supply pressure to the top of the cooler and return from the bottom, you're creating a waterfall effect with the PS fluid. Make sure it goes bottom to top, THEN returns to the PS pump reservoir.
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  #21  
Old January 10th, 2021, 18:41
lordoeuf lordoeuf is offline
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Re: Power steering cooler and cavitation during winter

Agreen, thank you for your comment.

1a) I wasn't aware that there is some sort of restriction in the trans cooler. A "tube that's flat?" You mean the bends of the pipe going back and forth? So perhaps these "feet of head" is causing too much back pressure to operate properly? I got the idea to use the stock trans cooler as a PS cooler from some youtube videos. Perhaps this wasn't a great idea after all?

1b) Are you sure the transmission cooler's pressure is lower than the low-pressure side of the power steering system? Isn't the highest pressure of the power steering's low-pressure side no more than around 50-100 PSI? The transmission cooler hoses that are sold have a max of 400 PSI, while the low-pressure power steering hoses tend to be 200 PSI.

2) The plumbing of the power steering system is such that the:

PUMP (1050 PSI) ----> GEARBOX (high pressure side) --[internal]--> GEARBOX (low pressure side) ----> COOLER (bottom) --[internal]--> COOLER (top) ----> RESERVOIR ----> PUMP

Is this the correct routing?
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  #22  
Old January 10th, 2021, 19:06
Agreen Agreen is offline
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Re: Power steering cooler and cavitation during winter

Oh yeah if it's return pressure then it's hardly anything at all. And yeah, that's the correct routing.

Transmission line pressure is like 100 psi. It's not as much as you'd think.

The transmission cooler is literally a flattened tube that is spiraled inside the end tank of the radiator. I personally wouldn't have used the radiator cooler because I'd think it's probably adding more heat to your PS system than removing it. In all my years I've never touched a stock power steering "cooler" (which is a short loop of steel tubing) and gone "damn that's hot!!". But I have been burned by radiators though. Maybe there's some engineering aspect that I haven't considered, but I also know that every time a car came to our shop for a transmission rebuild, we would bypass the factory trans cooler and install a tube and fin cooler on it to keep the transmission temps down. Heat will kill a transmission quickly, and being down south where air temps get in the 100's routinely, I wasn't taking the chance. Call it luck, call it overkill, but we never had a customer return with a burned up transmission.

I still think I missed the point of why you didn't use the stock cooler (lower case p-shaped tube)? You said it's because you're using a lunchbox locker in the front, but I'm not seeing why that has anything to do with power steering coolers. Maybe if you were using hydraulic assist steering you might need more cooling, but having a lunchbox locker really doesn't have any bearing on that IMO.
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  #23  
Old January 10th, 2021, 19:22
Black1990jeep Black1990jeep is offline
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Re: Power steering cooler and cavitation during winter

Quote:
Originally Posted by Agreen View Post
1) the trans cooler inside the radiator is a tube that's flat and can cause restriction so that could be an issue. Power steering pressure is higher than transmission line pressure.
2) if you have the cooler hooked up backwards it will definitely cause cavitation. If you have it plumbed to supply pressure to the top of the cooler and return from the bottom, you're creating a waterfall effect with the PS fluid. Make sure it goes bottom to top, THEN returns to the PS pump reservoir.
1) I assume he is using the stock auxiliary tranny cooler for power steering rather than the radiator water cooled one. Jeeps sold with the tow package had a tube and fin two pass cooler for the transmission, maybe a bit more than a foot long, it was mounted horizontally down near bottom of radiator, in front of radiator, it is an air cooled cooler.

So which is it, water cooled cooler, or auxiliary towing air cooled cooler?

2) 100% correct, since air rises over the fluid, always have the supply line at low
point, and return at high point do not mount in such a way to cause an air trap i.e. an inverted U in the system. Thus the stock two pass tube cooler is mounted horizontally. The supply (inlet) to this cooler should be the lower fitting, the return (outlet) is the upper fitting
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  #24  
Old January 10th, 2021, 19:23
Black1990jeep Black1990jeep is offline
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Re: Power steering cooler and cavitation during winter

and yes, the low pressure side goes to the cooler, NOT the high pressure side!
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  #25  
Old January 10th, 2021, 20:33
lordoeuf lordoeuf is offline
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Re: Power steering cooler and cavitation during winter

The trans. cooler is air cooled. It sits in front of the two other radiators in the very front of the car. This is the one I have (Dorman): https://www.rockauto.com/en/moreinfo...431776&jsn=412

Perhaps I should have gone with the cheaper SKF unit as it seems like the flow path may be less restrictive. https://www.rockauto.com/en/moreinfo...431776&jsn=411
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  #26  
Old January 10th, 2021, 21:34
lordoeuf lordoeuf is offline
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Re: Power steering cooler and cavitation during winter

Agreen, the Powertrax no-slip front locker puts noticable stress on the power steering pump when the locker is engaged. You can witness this when you try to make a turn, there is considerable resistance as the wheels want to return to centre, otherwise there must be slip between the tyre and ground on a turn. While in 2WD, there isn't any added stress on the power steering system, but when engaged, it is considerable from what I've witnessed.

After installing the locker, I took my Jeep wheeling and after a few hours, my original 2006 era high-flow AGR pump started leaking. I never had an issue with that pump for over a decade until I put the locker in. This is why I decided to add some sort of cooler to the power steering system once I replaced the AGR pump with the Lee pump.
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  #27  
Old January 11th, 2021, 10:37
Black1990jeep Black1990jeep is offline
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Re: Power steering cooler and cavitation during winter

Oh, AGR! Run away. A long time ago they had a decent reputation. Now days it is a new owner,
away from them Aholes. They tried to rip me off, sent me a junk gearbox, wrong size, then over billed me higher than the invoice. Then wanted me to pay to send it back. I stopped the credit card payment on them jerks. Rip off, run away! crooked thieving liars. AGR, = junk.
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  #28  
Old January 11th, 2021, 11:02
lordoeuf lordoeuf is offline
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Re: Power steering cooler and cavitation during winter

If I recall right, AGR still had a decent product in 2005-2006, which is why I mentioned the date.
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  #29  
Old January 11th, 2021, 19:50
Ed A. Stevens's Avatar
Ed A. Stevens Ed A. Stevens is offline
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Re: Power steering cooler and cavitation during winter

Quote:
Originally Posted by lordoeuf View Post
Sorry, but I don't quite follow your question. The transmission oil cooler, which is being used as the power steering cooler, is mounted in the factory location. Whatever level that stock placement is, is where the radiator is. You are asking if the top of this stock trans. radiator is at a higher elevation than the power steering reservoir level. If not, make sure it is. But then your next line says to make sure the reservoir is higher than everything else in the system. This looks like a contradiction. Could you please clarify? The reservoir is the power steering component with the highest elevation.

I don't see any sign of a vent in the Lee Power Steering reservoir cap. This is what the Lee pump and reservoir look like: https://leepowersteering.com/collect...e-xj-1987-2001

In the description on the Lee website, it says the pump/reservoir "includes our Zero Cavitation reservoir with pressurized no leak cap that is perfect for aggressive wheeling." So it sounds to me like the reservoir is NOT supposed to be vented. Apparently the reservoir has some special flow design which is supposed to make it not cavitate. How well that works, I don't know.
You need a vented cap or other method to expel the bubbles in the reservoir (drill and tap a nipple for a vent hose).

The increased pressure in the system is expansion of the normal bubbles in the fluid as it heats up, causing the cavitation as the fluid drops pressure in the gear box, because the bubbles cannot escape in the tank as the pressure keeps the vapor mixed in the fluid (much like the CO2 in a beer bottle stays suspended in the beer under pressure... until vented).

Lee's hi pressure / low cavitation claims defy the physics of partial pressures at the pressure drop through the gear box.

BTW, my 88 has identical return line routing through the factory tube fin tow package cooler (the AW4 has a larger cooler). Stock style pump, gear box, and ZJ links, on 33x12.5's with no cavitation (for 20 years).
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  #30  
Old January 11th, 2021, 22:26
lordoeuf lordoeuf is offline
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Re: Power steering cooler and cavitation during winter

Ed A. Stevens: Thank you for your comments. I appreciate it.

My guess is that the Lee reservoir is not fully pressurised to pump pressure. 1K PSI would be way too high. The reservoir must be at some lower pressure, perhaps 30 PSI? Under the reservoir cap there is a flat washer-like spring, which provides back pressure to the user when they press the cap down onto the reservoir, and under the spring is a large rubber seal, which is just a wide flat rubber washer. Perhaps this combination cannot form a prefect seal - I mean, that spring would have to be fully flattened and even then, the metal-to-metal part of the sprint-to-cap won't completely seal. But as I hear a pop when removing the cap, we know that the reservoir is not at atmospheric pressure (ATM).

This begs the question, what minimum pressure in such a system is needed for air to come out of solution (ps fluid)? Perhaps whatever pressure remains in the reservoir is still low enough for air to come out of solution, that is, since the fluid in the gear box is pressurised, wouldn't you only need the reservoir pressure to be lower than the gear box pressure for air to escape [into the pressurised air of the reservoir]? Obviously, the greater the pressure delta, the faster the air escapes. Note that the top half of the reservoir is meant to be left as air.

I cannot imagine that with all the vehicles that Lee supplies that they have such a basic flaw in their design. Perhaps the wording on their website can be interpreted incorrectly.

There was no issue driving the Jeep today, which was surprising. However, I still intend to drive it with the rubber washer removed from the cap to see if it feels any different.
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