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Discussion Starter #1
I left the car outside last night in the cold weather and this morning when I first started it up the steering was noticeably different … i.e., much easier to turn the steering wheel. It was so different I got out and checked under the car to make sure a tie rod or something hadn't come loose. Checked tire pressure manually even though there was no dash indication anything was amiss. The tire pressure was a little lower (32psi) than usual as expected due to the cold weather. As I continued to drive, the steering started to become, for lack of a better word, "stiffer" again. Short of putting a trigger pull gauge on a spoke of the steering wheel, the best way I can quantify this is, that normally, I can't easily make turns using the heel of palm of my hand like I do on my other cars. I'd guesstimate it was almost half the effort to steer during normal warmer Florida weather.. Any ideas on what's going on and suggestions on how to make it easy to steer all the time?
 

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That's an expected behavior.

The pressure in the power steering system is regulated by a bypass-style relief valve in the pump. When the oil is cold and thick, it has a harder time passing through the relief valve, so pressure may be higher. It usually takes no more than a few minutes of engine running for the oil to start warming up and flowing through that valve.

We often find that you can "tune" the assist slightly by using a different viscosity oil in the system. Major changes require a spring change, either in the relief valve or at the "spool valve" where the steering wheel inputs to the pinion gear in the rack-and-pinion assembly. The relief valve change puts higher pressure on hoses and seals so is the less desirable option. Changing the little torsion spring in the spool valve takes a little more care. The rack and pinion come out, the pinion and valve get carefully removed. The little spring is in the middle of the spool valve, comes out and is carefully "relieved" into a slight dogbone shape so it twists more easily. Then the pinion and valve get new seals, and is re-indexed to the rack inside, reinstalled in the car and alignment (toe) is verified.

You may have luck finding a similar model that has more assist, and swapping the pinion and spool valve from that into your existing steering gear. You might look at the Odyssey or MDX as a candidate.

For most drivers, the effort to modify is greater that the difference in effort to steer.

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I use ATF in my power steering and find the effort is consistent with the Honda-recommended power steering fluid. That system gets flushed every couple years when braked fluid gets changed, FWIW. There are heavier hydraulic oils packaged as power steering fluid for some Mopar models that might offer a slight reduction in steering effort. Fluid manufacturers/suppliers are required to supply a MSDS (material safety data sheet) and that often includes viscosity and pour-point numbers that might help you decide on what to try. The results of changing the fluid viscosity aren't nearly as consistent as a spool valve change or modification, though.
 

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Discussion Starter #3
That's an expected behavior.
For most drivers, the effort to modify is greater that the difference in effort to steer.
Thanks, dr bob … glad to know I'm not imagining this. I appreciate all the alternatives you provided to ease the steering effort but I guess I fall into the group of "most drivers" who find the effort greater than the benefit. Although, when it's time to change the PS fluid I may give a more viscous ATF a try. Ever try Valvoline MaxLife ATF in your PS?
 

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MaxLife has the same viscosity as "normal" Dexron/Mercon, so nothing special about it for power steering use. I've been using MaxLIfe in the auto gearbox for a few years now. I'd have to look to see if the Pilot PS gets that or Mobil-1, the stuff the German toys seem to like a lot. It's generally determined by what's out for other services. Sorry, not very scientific. I'll try to remember to note it in the logbook next change.
 

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Discussion Starter #5
MaxLife has the same viscosity as "normal" Dexron/Mercon, so nothing special about it for power steering use.
OK thanks … I thought MaxLife might have a higher viscosity based on claims it cures TC shudder/vib problems since my low speed shudder/vib issue disappears when the weather gets cold (assuming the stock Honda ATF has a higher viscosity at lower temps).

Is there such a thing as multi viscosity PS fluid or ATF similar to 0w-20 motor oil? I could be wrong but I'm thinking a thicker PS fluid might put too much pressure on the system when it is cold. If not, I'm starting to think I might not tempt fate since while I like the easier steering on cold mornings, the steering normally is ok enough to leave alone.
 

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Sorry, no such thing yet as long-chain molecules in hydraulic oil. The use nature of the pumps ("high shear gear pumps") in typical hydraulic service make that impossible. Plus no need -- we add power steering coolers to our cars to keep temps stable. So long as PS oil temps stay below 225ºF or so, we generally don't care about cold pour point or viscosity. Remember that the multi-grade motor oils don't get thinner when colder, as you might believe looking at the grades. The numbers refer to equivalent film strength at freezing (32ºF) and boiling (212ºF) temps. Still thicker when cold, but those long-chain molecules maintain adequate film strength even as the base thins out as it gets hotter. Hydraulic service relies on the viscosity to determine flow capability at a specific pressure drop through a specific orifice size. In this case the orifice is the available opening in the bypass passage in the pump.

Another thing to consider in your cold-morning experience is the tires. Colder rubber slides more easily on cold pavement. In Florida you likely have summer or maybe two-season tires similar to what shipped from the factory on your car. Those wear OK but the payback is that they grip way less in the cold. The ultra-performance summer tires on my summer driver are like driving on greased bricks when cold on cold (<40ºF) pavement. Below freezing temps they are unsafe at speed, that's how much they fall off with cold. The toys hibernate from about Thanksgiving to Easter here, and the Pilot gets moved to full-time DD duty. We live at altitude near a ski area, rather than the warm humid soggy miserable (my description from experience...) climate that plagues Florida most of the year. I used the original tires to about half worn then gave up and put 4-season tires on. Tremendous difference. Not worth the change for a few days of cooler temps that you see each year where you live though.
 

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Yes, until the PS fluid warms up the Pilot has notably more assist. Tire pressure makes a significant difference. Isn't 35 PSI on the door placard?

I have known people who've added an ounce (or so) of "motor honey" to a PS reservoir (on a Ford). They did it to reduce leaking from a bad pump seal, but also got an uptick in steering assist.
 

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Discussion Starter #8
Sorry, no such thing yet as long-chain molecules in hydraulic oil. Hydraulic service relies on the viscosity to determine flow capability at a specific pressure drop through a specific orifice size. In this case the orifice is the available opening in the bypass passage in the pump.

Another thing to consider in your cold-morning experience is the tires. I used the original tires to about half worn then gave up and put 4-season tires on. Tremendous difference. Not worth the change for a few days of cooler temps that you see each year where you live though.
OK got it on the difference between motor oils and hydraulic oil. Any suggestions for a PS fluid with higher viscosity? Lucas? Amsoil?
I thought about the tires being a variable due to temp. I guess jacking up the front end and putting a pull gauge on a steering spoke at different outside temps would be more "scientific" but for that much bother I don't think it would tell me anything new that I don't already know. But you bring up a good point I hadn't considered. The tires currently on the vehicle are the Michelins recommended by Honda.
 

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Discussion Starter #9
Yes, until the PS fluid warms up the Pilot has notably more assist. Tire pressure makes a significant difference. Isn't 35 PSI on the door placard?

I have known people who've added an ounce (or so) of "motor honey" to a PS reservoir (on a Ford). They did it to reduce leaking from a bad pump seal, but also got an uptick in steering assist.
I considered that tire pressure might be a factor and actually measured it when I first noticed the easier steering that first cold morning the car was left outside. I normally keep it at spec, 35psi, on that cold morning it was 32psi. I would think, if anything, being "flatter" that would make it harder to steer unless the rubber got so hard it wasn't grippng the ground as well.

"motor honey" ….? What is that? STP?
 

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OK got it on the difference between motor oils and hydraulic oil. Any suggestions for a PS fluid with higher viscosity? Lucas? Amsoil?
...
I'm not a fan of using oils that are a lot different from mfrs' recommendations, so no specific guidance from me on this.

Take a look at the MSDS (material safety data sheet) info on your candidate oils and see what might work. The one you select will be tailored towards a car brand and the power steering systems they use, not a particular fluid manufacturer. ie: look for a fluid for a Chrysler, Ford, GM, whatever, rather than a brand like Amsoil or Valvoline. Once you decide on what you want, you'll purge the old stuff to make room for new, then burp any air out to eliminate the groaning from the pump and relief valve -- air makes squeals and groans in the pump bypass, and the air mixes right back into the oil in the reservoir to do it again.
 

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Discussion Starter #11
I made a viscosity meter of sorts and took some PS fluid out of the reservoir and ran it through a 0.187" orifice at 80*F which took 5 seconds for 1 oz. Then I cooled it down to 40*F and ran the same test which took 15 seconds. Quite an increase in viscosity over that temp range. I wonder if a large cooler in front of the radiator for the PS using the regular Honda PS fluid would help maintain a higher viscosity and yield easier steering?
 

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I'm not a fan of using oils that are a lot different from mfrs' recommendations, so no specific guidance from me on this.

Take a look at the MSDS (material safety data sheet) info on your candidate oils and see what might work.
From what I'm reading here and elsewhere about Honda PS seals deteriorating from off spec PSFs, I don't blame you!
Many of the alternatives that do list viscosity numbers at various temps are lower in the 6.x-7.x range than Honda's at 11.x at 100*C. Soooo … based on various horror stories from people who have had to rebuild/replace leaking racks and/or pumps, I think I'll stick with the Honda PSF and at $17 for a 3-pak off Amazon free next day delivery (Prime), I can't see searching any further. The fluid in there now is about the color of tea and I can't find any record of it ever being changed so maybe new fluid with fresh additives will result in the desired easier steering.

Just curious … do 2nd gen Pilots characteristically have stiffer steering than other cars either due to their weight or some other reason? I'm hoping the answer is "no" which gives hope to an improvement with new fluid.
 

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I made a viscosity meter of sorts and took some PS fluid out of the reservoir and ran it through a 0.187" orifice at 80*F which took 5 seconds for 1 oz. Then I cooled it down to 40*F and ran the same test which took 15 seconds. Quite an increase in viscosity over that temp range. I wonder if a large cooler in front of the radiator for the PS using the regular Honda PS fluid would help maintain a higher viscosity and yield easier steering?
It might, but the fluid heats in the pump casing, right where you might want it to be a little thicker so flow is slowed through the internal pressure regulator. Cooling the fluid to 80ºF on most days will be close to impossible. ASSuming that the cooler would get the oil temp all the way down to ambient temp, the pump still heats it back up some.

The 2WD cars come with a simple two-pass tube and fin heat exchanger. Goal is to keep the fluid below about 225ºF typically. 4WD and a factory retrofit cooler at least doubles the cooler area, but in fact towing doesn't really change the amount of heat added to the fluid by the pump except when you do a lot of backing an turning and have low airflow. Know that the fluid cooler lives in the return line to the reservoir, so you can use any automatic transmission cooler to shed more heat. A large cooler would be ideal for the power steering , but interrupts more airflow otherwise needed for actual transmission fluid and engine cooling. Move the aftermarket PS cooler below and to the side, add fans or buy a package with fans... Typically more work than a casual DIY might want to take on.

Maybe spend more time doing curls with the dumbbells to reduce the steering effort percentage. ;)
 

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Discussion Starter #14
It might, but the fluid heats in the pump casing, right where you might want it to be a little thicker so flow is slowed through the internal pressure regulator. Cooling the fluid to 80ºF on most days will be close to impossible. ASSuming that the cooler would get the oil temp all the way down to ambient temp, the pump still heats it back up some.

The 2WD cars come with a simple two-pass tube and fin heat exchanger. Goal is to keep the fluid below about 225ºF typically. 4WD and a factory retrofit cooler at least doubles the cooler area, but in fact towing doesn't really change the amount of heat added to the fluid by the pump except when you do a lot of backing an turning and have low airflow. Know that the fluid cooler lives in the return line to the reservoir, so you can use any automatic transmission cooler to shed more heat. A large cooler would be ideal for the power steering , but interrupts more airflow otherwise needed for actual transmission fluid and engine cooling. Move the aftermarket PS cooler below and to the side, add fans or buy a package with fans... Typically more work than a casual DIY might want to take on.

Maybe spend more time doing curls with the dumbbells to reduce the steering effort percentage. ;)
Well there's that solution of couse, don't exercise enough as it is. I'm just wondering if there's something wrong with my PS or if I'm just a weakling.

When the car is first started up and the ambient temp is 50*F or below, as I back out of the garage and turn into the turnaround, I can swing the steering wheel literally with one finger in a spoke. By the time the ECT starts to register above bottom on the gauge, the steering becomes stiff enough that I cannot easily make turns with one finger. A good thing from a safety perspective since I normally drive with both hands on the wheel and steer hand over hand, but it's my best description at quantifying the effort needed to steer my Pilot cold vs warmed up

Since it is a 4WD shouldn't there be some kind of cooling radiator let alone a four pass one. There is a small radiator on the driver's side but the lines to and from I don't appear to be part of the PS. In a parts blow up, the PS return pipe along the bottom front of the radiator shows having fins but mine is just a straight pipe. But as you say, even if it did have fins, it wouldn't get the fluid down to ambient let alone below 50*F except in very cold weather. I may look into why it not only doesn't have a four pass cooler let alone a finned return pipe given it's a 4WD. Steering effort aside, I'm wondering if the uncooled PS fluid temp is shortening pump and or seal life.

This is what I believe is the PS return line that is supposed to have cooling fins. It's just a straight pipe the width of the radiator.
134276


Could this be the PS cooler?
134277

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Discussion Starter #15
Update ... the weather is finally warming up here in Florida, which brought back the stiffer steering in my Pilot. Steers easy in cold weather, not so much when warm/hot. A PS fluid viscosity/pressure relief valve thing I'm told.

By chance I had to drive my MiL's Mercedes the other day and noticed it's about the same effort to turn as the Pilot. On the other hand, our other vehicles, a Rogue and a Quest, are much easier to steer in any weather. But I now notice they also feel like they "over steer" at high speed highway driving, i.e. rapid lane changes, etc. The Pilot and Mercedes feel more controlled at high speed. I guess if it's a trade off I'll take the better safer handling at high speed. So, since I can't "adjust" the Pilot steering to be easier at low speed parking manuevers, I've adjusted my attitude about it being a problem, so problem solved! :cool:
 

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Regular comments on my German cars' steerings are that they are heavy and ponderous at low speed. By 40 they are great, and are still three-finger drives at 150+. After driving those as not-winter drivers, the Pilot seems like it has pretty easy steering.

One of the now-gone British toys is a very early S1 Lotus Europa. A little over 1000 lbs, mid-engined and no power steering. On street tires you can stick a finger in a steering wheel spoke (10" wheel with metal spokes....) and spin it the whole 3/4-turn between lock limits. Pretty darn effortless. Dangerous if you don't expect it. Rockin' fun if you do. The Pilot, not so much.
 

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Discussion Starter #17
Regular comments on my German cars' steerings are that they are heavy and ponderous at low speed. By 40 they are great, and are still three-finger drives at 150+. After driving those as not-winter drivers, the Pilot seems like it has pretty easy steering.

One of the now-gone British toys is a very early S1 Lotus Europa. A little over 1000 lbs, mid-engined and no power steering. On street tires you can stick a finger in a steering wheel spoke (10" wheel with metal spokes....) and spin it the whole 3/4-turn between lock limits. Pretty darn effortless. Dangerous if you don't expect it. Rockin' fun if you do. The Pilot, not so much.
What gets me is the Pilot steers so nice and easy when cold. But within a few minutes when the PS fluid warms up and thins out, it sneaks though that relief valve and much of that helpful assist pressure is lost. I don't know how it would handle at high speed, but the PS fluid is already warmed up and thinned out by the time I get to a road with multiple lanes and a >50mph speed limit.
 

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I find our Pilot always has very light steering. After driving the Traverse with the heavy steering I feel like I'm losing traction, especially in bad weather. I personally like the heft of the Traverse better, it feels more connected and I feel like I know when the front wheels are losing traction in bad weather better.

If you want heavy steering come drive my Impala. It weights somewhere around 3500 lbs and has an iron block V8 sitting over the front wheels. At a stop I can barely move the wheels even with the gigantic steering wheel. Get moving 2 or 3 mph and it lightens up nicely and is no problem to drive. I've learned the key to that vehicle is make most steering movements while in motion.
 

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Discussion Starter #19
I find our Pilot always has very light steering. After driving the Traverse with the heavy steering I feel like I'm losing traction, especially in bad weather. I personally like the heft of the Traverse better, it feels more connected and I feel like I know when the front wheels are losing traction in bad weather better.

If you want heavy steering come drive my Impala. It weights somewhere around 3500 lbs and has an iron block V8 sitting over the front wheels. At a stop I can barely move the wheels even with the gigantic steering wheel. Get moving 2 or 3 mph and it lightens up nicely and is no problem to drive. I've learned the key to that vehicle is make most steering movements while in motion.
Yep, its's all relative. When I drive my wife's Rogue the steering feels too sensitive at highway speeds, although it's nice and "one finger" easy to steer into tight parallel parking spots. On the other hand, our Quest van steers nice and easy at low speed but is not overly sensitive on the interstate.
 
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