Jeep Power Steering Fluid

[greglarsen56]

My 2005 Jeep Grand Cherokee has a 7,500 mile change interval for the power steering fluid. This is because the power steering pump provides hydraulic pressure to run the engine cooling fan. Does this change interval make sense to you guys?

Thanks.

 

[unDummy]

What a hassle!!!!!

With the movement to maintenance-free vehicles, what the he1l is Jeep doing?

http://www.electricfanengineering.com/hydraulic.htm

http://www.hbus.haldex.com/products/fds.htm

http://www.cat.com/cda/files/297293/7/Hydraulic_Fan_Brochure_WEDE1241-2.pdf

http://hydraulics.eaton.com/products/pdfs/E-SYFD-MR001-E2.pdf

ftp://www.denisonhydraulics.com/Literature/HydraCOOL Fan Systems/SP0-AM334_FanDrive-Applications.pdf

Does Jeep make it easy to change the PSF every 7.5k miles? Does it have a sump or is it just sharing the PSF reservoir?

Inteval makes sense. Consult the factory service manual for specifics. If you're lazy, maybe an increase in fluid capacity, via external sump, will allow you to drive longer intervals.

Remind me not to buy a used Jeep without PSF change records.

 

[greglarsen56]

Thanks for the response unDummy. Your links gave me a better understanding of why Jeep chose this design.

 

[Hootbro]

quote:

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Originally posted by greglarsen56:
Does this change interval make sense to you guys?

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Just leave it in until the car explodes. Why second guess the engineers who designed it and spent millions in research and put that spec in the owners manual?

Power steering fluid driving the cooling fan is something new. I would follow the onwers manual untill design is more mature and see what kind if any failure feedback comes around on this.

Hootbro

 

[Gary Allan]

I don't understand why they did it. The thing is a gas hog ..what advantage can this feature offer over electric (I read most of the promotional stuff)?

It's along the lines of that DOD Hemi. Just don't buy the thing if you're looking for any hint of economy. It's not that economical to offset the total wasteful nature of the vehicle to begin with

 

[47HO]

BTW, it's not that new. My 2002 Jeep GC uses the same system. I can't find anywhere in my manual about a 7500 mile change interval.

Anyhow, at 45k miles I haven't changed it and still have no problems!

 

[VNT]

It is actually a good system. My 02 WJ uses the hydraulic fan and an electric fan.

PS reservoir uses ATF+4. just get a turkey baster and by some Amsoil ATF, Twice a year when you are changing oil, replace some PS Fluid. I do this and aslo freshen up the brake fluid at same time.

Oh friend just bought an 06 WK Hemi is geting about 22 MPG highway on trip to Carlisle PA, so I wouldnt call the hemi with MDS a gas hog. Very nice rig and hauls ***!

 

[Tremo]

Wow!! Using a hydraulic motor to run the radiator fan. How strange. But I've heard of other ideas like this. No doubt it is a variable speed drive so they can control the amount of cooling better. Another car manufacturer (forgot who) uses a variable speed electric fan on their engines.

What a crock, too complicated.

Back to the original question. It seems logical that the reason they are requiring such a frequent change interval is because the fluid is getting a hard workout running both the steering as well as the fan motor. It probably runs hot as ****.

It's best to observe the factory recommended change intervals if you want a trouble free car. However, if you insist, you could go with synthetic PS fluid, and put on a big fluid cooler. A larger capacity reservoir would also be a good idea. But all that is just more hassle. Follow the factory.

 

[XS650]

quote:

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Originally posted by Tremo:
Wow!! Using a hydraulic motor to run the radiator fan. How strange. But I've heard of other ideas like this. No doubt it is a variable speed drive so they can control the amount of cooling better. Another car manufacturer (forgot who) uses a variable speed electric fan on their engines.

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C6 Corvette has an electric variable speed fan.

 

[greglarsen56]

Thank you all for the insight.

Greg

 

[gtx510]

quote:

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Originally posted by VNT:
It is actually a good system. My 02 WJ uses the hydraulic fan and an electric fan.

PS reservoir uses ATF+4. just get a turkey baster and by some Amsoil ATF, Twice a year when you are changing oil, replace some PS Fluid. I do this and aslo freshen up the brake fluid at same time.

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Hydraulic fan? I thought it was a viscous-clutch fan? When the clutch heats up it locks and the fan spins. Otherwise the fan kinda freewheels to free up hp.

If you want to see interesting uses of Ps fluid look at the hydro brake booster on the 90's Lincoln MK's. Or the "hyrdracharger" turbo systems Garrett was developing before ball-bearing technology catch up.

And your WJ should use ATF+3 (now ATF+4) in the tranny. And the PSF needs to meet Daimler-Chrysler MS-5931 specs. Valvoline Synpower or Redline PSF would both work.

 

[VNT]

Me bad your correct on the PS Fluid, I have too many vehichles, I use the synpower in the WJ and ATF+4 in my PT.

per their reason from WJJeeps.com

Cooling fan, industry-first hydraulically driven engine cooling fan on 4.7-liter engine for increased fuel economy and efficiency. Attached to radiator assembly and powered by power steering system for more efficient and quieter operation

 

[gtx510]

Woah!! Really? I'm gonna have to take a peek when pops gets home.
I guess that would explain the special PSF, tiny PSF cooler, and why my dad's fluid smelt so burnt (people had been adding D/M).
Thanks for the info.

I too use Synpower for the WJ, and mumzies BMW gets Redline.

Have you found a ATF+4 other than Valvoline or Redline?

 

[VNT]

I use Amsoil universal ATF in all my +4 applications, great stuff. For the PS in my older cars I use the synpower.

I really dont think the PS in the jeeps are a problem. Mine has a cooler and the fluid always looks clean but I still change some via the turkey baster method. In all probabilty, most ownwers never change it.

quote:

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Originally posted by gtx510:
Woah!! Really? I'm gonna have to take a peek when pops gets home.
I guess that would explain the special PSF, tiny PSF cooler, and why my dad's fluid smelt so burnt (people had been adding D/M).
Thanks for the info.

I too use Synpower for the WJ, and mumzies BMW gets Redline.

Have you found a ATF+4 other than Valvoline or Redline?

---

 

[Tremo]

All hail the mighty turkey baster! I use it! A tool every home garage mechanic should have!

 

[gtx510]

I checked and it looks like the WJ has a regular viscous clutch fan. At least the '00 V8 model I looked at did.
It'd be good to replace it with an electric one controlled by a thermostat/switch.

I lost my turkey baster so I used a gatorade bottle, some fishtank airhose, and a vacuum pump (like a mityvac).
Reamed 2 holes in the cap with a screwdriver, put the hose thru (doesn't need to go in far, vacuum....), and sealed with RTV.

The PSF in pops' (80k mile) WJ looked like the oil change monkeys had been adding ATF.
Smelt a bit like burnt D/M3 and was dark red/brown. Holding it up to the light you couldn't see thru a small gatorade bottle full of it.

I've drained and refilled the reservoir twice now, the fluid still looks dark, and I'm using (clear) Synpower.
I'm thinking of getting a male-to-male hose fitting that fits the PS return line and flushing the entire system.

FWIW, the tranny will probably get Redline C+ ATF.
www.redlineoil.com/products_gearlubricants.asp?pvID=78&prodID=59&subcatID=19

 

[1040 WreckerMan]

Hydraulic fan drives are nothing new. They have been used on HD equipment, trucks and buses for many years. The advantage of an engine driven fan over an electric fan is airflow. No electric fan can move as much air as an engine driven fan of the same size within the size constraints of the engine compartment. Most electric fans are rated in "free air" with no restrictions. When the fan is installed in the vehicle the engine creates a restriction and lowers the actual CFM that the fan can deliver. In the case of some smaller gas engines this is acceptable. In the case of larger gas or diesel engines you will need more HP available than an electric 12V motor is capable of running (remember most charging systems don’t have more than 130 amps factory give or take some).

Hydraboost brake systems are still widely used in SUV’s and trucks. The Ford SuperDuty has used them for years, GM/Chevy HD’s/4500/5500/etc use them. They are far more consistent than vacuum boosters, and necessary on diesel vehicles that create no vacuum.

I change the contents of the PS pump reservoir every other engine oil change. I think 7500 is about right on a small reservoir sever duty schedule, otherwise at least double that would be fine. If you are worried about contaminants you can put a filter in the return line. If the fluid is getting too hot a smaller cooler for PS can be added. I also am a fan of using good hydraulic oil in the PS system since it has good adds for the pump/cyls/motor. The PS system generally doesn’t need any FM that comes with ATF. My .02 worth anyway.

 

[brianl703]

quote:

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Originally posted by Tremo:
Another car manufacturer (forgot who) uses a variable speed electric fan on their engines.

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Saab has this on the 9-3.

It's not infinitely variable, but it offers at least 4 speeds.

 

[VNT]

GTX510

The changed the set up in 2002 to the new system.

 

[gtx510]

Interesting, VTN. Thanks for letting me know. I still don't think it'll help me talk pops into a elec. fan swap.

2-speed elec. fans have been around for a while. Now a 4-speed one shows really nice. Any chance that there's super thin ones out there? OEM or aftermarket.