Power Steering Fluid Drain & Flush
01-13-2013, 11:31 PM
#1
Rennlist Member
Thread Starter
Power Steering Fluid Drain & Flush
Having searched RL and Google, none was found other than the turkey baster method (aka dilution method) of changing the power steering fluid.
With my 993 at 18 years of age and not knowing if the power steering fluid had ever been changed, I decided upon a complete drain and flush. Yes, this is far more time consuming than the turkey baster method; the choice is yours.
Lets start by having 2 bottles of Pentosin CHF 202 Power Steering Fluid on hand, or whatever the flavor is the day you read this.
-------------------------------------------------------------------------------------------
Note: the photo follows the set of instructions.
Removal of the front underbelly cover is done by removing the upper five plastic flanged nuts (small flange), the two lower outer plastic flanged nuts (large flange) and two lower (center) stainless steel bolts with washers.
A 10 mm socket is required on an extension and ratchet.
Note: the stainless steel bolts thread into the aluminum frame member behind the underbelly cover. They might be seized. One of mine was seized and it took over an hour to remove using a penetrant and repeated fastening/unfastening of the stainless steel bolt. And because the fastener threads into a blind hole, the penetrant can only be applied between the cover and the aluminum frame member. After it was removed, a M6 bottoming tap was run into the threaded blind hole to clean the threads. White powder (aluminum oxide?) came out. Patience saved the day. The threads of the stainless steel bolts have since been coated with an anti-seize paste.
With the front underbelly cover removed, the steering rack is exposed.
The two power steering lines from the power steering pump that connect to the steering rack are connected with banjo bolts and sealing rings (yellow dots).
The metal line is the pressure line from the power steering pump and the rubber hose which then turns into a plastic line, is the return line (no pressure).
Originally, I intended to remove these to drain the power steering system. Poor accessibility and the fact that some power steering fluid will still remain in the steering rack changed that plan.
The two hydraulic lines (yellow dots) into the steering rack are held in place by threaded fittings.
A 12 mm flare nut wrench (preferably) or a 12 mm open end wrench is used to loosen the threaded fittings. The fittings were not tight.
With one of the power steering lines removed, the power steering fluid drained. It drains slowly, so you might want to take a break.
Note: these hydraulic fittings are not like those used in brake systems. There is an O-ring at the end of each power steering line that should be replaced. Unfortunately, the O-rings are not available from Porsche; at least they are not shown in the Porsche parts catalog. I reused the O-rings, but I was extra careful removing them to inspect them for damage. They were slightly stiff, but a very long way from being brittle.
The original O-rings measured (and I know they don't add up; O-rings are difficult to measure):
ID: 5.60 mm, 0.2205"
OD: 9.13 mm, 0.3595"
CS: 2.00 mm, 0.0790"
Tie the hydraulic lines to the black plastic return line using tye-wraps. This gets the lines slightly out of the way. The hydraulic lines are stiff due to their short length; no not bend them.
The ends of two vinyl hoses (ID: 5/16", OD: 7/16") long enough to insert into a container were inserted into the steering rack where the hydraulic lines were removed.
With the engine off, the steering was cycled through its range back and forth a few times to drain the steering rack.
Slip a snug fitting vinyl hose over the end of each hydraulic line (only one hose shown in this photo) and place the other ends in a container.
Remove the DME relay and using the ignition key, crank the engine over for a few seconds while rotating the steering wheel back and forth. Observe the previously clear vinyl hoses to verify if any additional old power steering fluid has drained.
Fill the power steering fluid reservoir with fresh power steering fluid (Pentosin CHF 202). Crank the engine over again for a few seconds while moving the steering wheel back and forth. Verify if fresh power steering fluid has been pumped through the drain lines (Pentosin CHF 202 should be green in color).
When the fresh power steering fluid has ceased to drain, remove the four vinyl hoses previously installed.
Carefully reinstall the O-rings on the hydraulic lines. Apply a thin smear of Dow Corning MolyKote 55 O-ring lubricant to the O-rings.
Carefully insert the hydraulic lines back into the steering rack keeping them square and thread the fittings back on. Do not over tighten the fittings; the O-rings create the seal.
Wipe the area around the fittings with a damp cloth soaked in alcohol. The area should appear dry so that you can check for leaks later.
Prior to adding any power steering fluid, the inside of the power steering fluid reservoir was cleaned. An insignificant amount of soot was found on the base plate.
Normally I would remove the power steering fluid reservoir for a thorough cleaning, but it could only be removed by cutting the Oetiker Stepless Ear Clamp on the return hose (not visible - behind the hose to the power steering pump). The hose to the power steering pump has a screw clamp as can be seen.
Fill the power steering fluid reservoir to within an inch of the top with Pentosin CHF 202.
Reinstall the DME relay and start the engine for 5 seconds while rotating the steering wheel back and forth. Check the hydraulic lines at the steering rack for leaks. If no leaks are noted, refill the power steering reservoir and repeat this step, this time letting the engine run while gently turning the steering wheel fully to each end a few times (do not slam the steering wheel to its stop).
Check the power steering fluid level in the reservoir and top up as necessary.
If at any time the power steering pump is sucking air, shut the engine off immediately and add power steering fluid.
Double check for leaks at the hydraulic lines at the steering rack.
Reinstall the underbelly cover and reconfirm the level of the power steering fluid.
Next year when I perform this task again, I will be installing a power steering fluid filter in the return line at the reservoir.
With my 993 at 18 years of age and not knowing if the power steering fluid had ever been changed, I decided upon a complete drain and flush. Yes, this is far more time consuming than the turkey baster method; the choice is yours.
Lets start by having 2 bottles of Pentosin CHF 202 Power Steering Fluid on hand, or whatever the flavor is the day you read this.
-------------------------------------------------------------------------------------------
Note: the photo follows the set of instructions.
Removal of the front underbelly cover is done by removing the upper five plastic flanged nuts (small flange), the two lower outer plastic flanged nuts (large flange) and two lower (center) stainless steel bolts with washers.
A 10 mm socket is required on an extension and ratchet.
Note: the stainless steel bolts thread into the aluminum frame member behind the underbelly cover. They might be seized. One of mine was seized and it took over an hour to remove using a penetrant and repeated fastening/unfastening of the stainless steel bolt. And because the fastener threads into a blind hole, the penetrant can only be applied between the cover and the aluminum frame member. After it was removed, a M6 bottoming tap was run into the threaded blind hole to clean the threads. White powder (aluminum oxide?) came out. Patience saved the day. The threads of the stainless steel bolts have since been coated with an anti-seize paste.
With the front underbelly cover removed, the steering rack is exposed.
The two power steering lines from the power steering pump that connect to the steering rack are connected with banjo bolts and sealing rings (yellow dots).
The metal line is the pressure line from the power steering pump and the rubber hose which then turns into a plastic line, is the return line (no pressure).
Originally, I intended to remove these to drain the power steering system. Poor accessibility and the fact that some power steering fluid will still remain in the steering rack changed that plan.
The two hydraulic lines (yellow dots) into the steering rack are held in place by threaded fittings.
A 12 mm flare nut wrench (preferably) or a 12 mm open end wrench is used to loosen the threaded fittings. The fittings were not tight.
With one of the power steering lines removed, the power steering fluid drained. It drains slowly, so you might want to take a break.
Note: these hydraulic fittings are not like those used in brake systems. There is an O-ring at the end of each power steering line that should be replaced. Unfortunately, the O-rings are not available from Porsche; at least they are not shown in the Porsche parts catalog. I reused the O-rings, but I was extra careful removing them to inspect them for damage. They were slightly stiff, but a very long way from being brittle.
The original O-rings measured (and I know they don't add up; O-rings are difficult to measure):
ID: 5.60 mm, 0.2205"
OD: 9.13 mm, 0.3595"
CS: 2.00 mm, 0.0790"
Tie the hydraulic lines to the black plastic return line using tye-wraps. This gets the lines slightly out of the way. The hydraulic lines are stiff due to their short length; no not bend them.
The ends of two vinyl hoses (ID: 5/16", OD: 7/16") long enough to insert into a container were inserted into the steering rack where the hydraulic lines were removed.
With the engine off, the steering was cycled through its range back and forth a few times to drain the steering rack.
Slip a snug fitting vinyl hose over the end of each hydraulic line (only one hose shown in this photo) and place the other ends in a container.
Remove the DME relay and using the ignition key, crank the engine over for a few seconds while rotating the steering wheel back and forth. Observe the previously clear vinyl hoses to verify if any additional old power steering fluid has drained.
Fill the power steering fluid reservoir with fresh power steering fluid (Pentosin CHF 202). Crank the engine over again for a few seconds while moving the steering wheel back and forth. Verify if fresh power steering fluid has been pumped through the drain lines (Pentosin CHF 202 should be green in color).
When the fresh power steering fluid has ceased to drain, remove the four vinyl hoses previously installed.
Carefully reinstall the O-rings on the hydraulic lines. Apply a thin smear of Dow Corning MolyKote 55 O-ring lubricant to the O-rings.
Carefully insert the hydraulic lines back into the steering rack keeping them square and thread the fittings back on. Do not over tighten the fittings; the O-rings create the seal.
Wipe the area around the fittings with a damp cloth soaked in alcohol. The area should appear dry so that you can check for leaks later.
Prior to adding any power steering fluid, the inside of the power steering fluid reservoir was cleaned. An insignificant amount of soot was found on the base plate.
Normally I would remove the power steering fluid reservoir for a thorough cleaning, but it could only be removed by cutting the Oetiker Stepless Ear Clamp on the return hose (not visible - behind the hose to the power steering pump). The hose to the power steering pump has a screw clamp as can be seen.
Fill the power steering fluid reservoir to within an inch of the top with Pentosin CHF 202.
Reinstall the DME relay and start the engine for 5 seconds while rotating the steering wheel back and forth. Check the hydraulic lines at the steering rack for leaks. If no leaks are noted, refill the power steering reservoir and repeat this step, this time letting the engine run while gently turning the steering wheel fully to each end a few times (do not slam the steering wheel to its stop).
Check the power steering fluid level in the reservoir and top up as necessary.
If at any time the power steering pump is sucking air, shut the engine off immediately and add power steering fluid.
Double check for leaks at the hydraulic lines at the steering rack.
Reinstall the underbelly cover and reconfirm the level of the power steering fluid.
Next year when I perform this task again, I will be installing a power steering fluid filter in the return line at the reservoir.
Last edited by IXLR8; 01-13-2013 at 11:51 PM.
01-14-2013, 09:38 AM
#4
Rennlist Member
Thread Starter
It already is, Dan. They all start on my photo hosting site.
Life would be easier if manufacturers would make PS fluid changes as easy as engine oil changes, not that PS fluid changes are needed all that often.
Life would be easier if manufacturers would make PS fluid changes as easy as engine oil changes, not that PS fluid changes are needed all that often.
01-14-2013, 09:55 AM
#6
Rennlist Member
Thread Starter
I'm blaming that influence on some really sick Rennlisters. Truth is, I hate working on dirty vehicles; my seriously rustproofed and filthy Honda CR-V for example. Motorcycles and aircraft are so much more fun to work on.
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01-14-2013, 02:54 PM
#8
Racer
Alex:
Wow!! Car is spotless. Looks brand new. Very impressive.
2 questions: what is the large black unit in front of your steering rack where my front diff would be (Lucas part # 993 355 025 10)?
Second: did you find anything useful to plug the Max Jax anchors on the garage floor while not in use to keep the inside clean?
--Brian
Wow!! Car is spotless. Looks brand new. Very impressive.
2 questions: what is the large black unit in front of your steering rack where my front diff would be (Lucas part # 993 355 025 10)?
Second: did you find anything useful to plug the Max Jax anchors on the garage floor while not in use to keep the inside clean?
--Brian
01-14-2013, 03:28 PM
#9
RL Community Team
Rennlist Member
Rennlist Member
Recently I replaced the rack on my car at 80K miles due to a fluid leak and in the process replaced the reservoir and fluid as well.
Your posting seems to suggest that the fluid replacing procedure presented is one others should contemplate.
I was wondering why?
Instead of breaking all the connections under the car could one just drain the reservoir and replace it, fill the new reservoir with fresh fluid, run the engine a little and drain and refill the reservoir again. I would think the power steering circuit is not like a brake line where fluid does not circulate and so bleeding is needed to refresh the somewhat static fluid in the brake lines. Also the only failure modes I know of for power steering is if the seals on the rack or pump dry out and leak. This seems to be an age / miles related issue.
I am not saying what you did was like paying for Nitrogen filled tires, in my opinion complete flimflam, just that I have not seen any technical test results showing any benefit of replacing the fluid and if so doing it in the comprehensive manner you discuss.
Andy
Your posting seems to suggest that the fluid replacing procedure presented is one others should contemplate.
I was wondering why?
Instead of breaking all the connections under the car could one just drain the reservoir and replace it, fill the new reservoir with fresh fluid, run the engine a little and drain and refill the reservoir again. I would think the power steering circuit is not like a brake line where fluid does not circulate and so bleeding is needed to refresh the somewhat static fluid in the brake lines. Also the only failure modes I know of for power steering is if the seals on the rack or pump dry out and leak. This seems to be an age / miles related issue.
- Does fluid really ever need to be replaced?
- Will refreshing the fluid prolong seal life?
I am not saying what you did was like paying for Nitrogen filled tires, in my opinion complete flimflam, just that I have not seen any technical test results showing any benefit of replacing the fluid and if so doing it in the comprehensive manner you discuss.
Andy
01-14-2013, 03:56 PM
#10
Rennlist Member
Thread Starter
Brian, I haven't really looked since I am leaving my MaxJax columns in place. What I would use are Caplugs that fit or a hex socket set screw. I'd go with disposable Caplugs...they can't get stuck in the anchor.
01-14-2013, 04:08 PM
#11
Rennlist Member
Thread Starter
Like any DIY on Rennlist or P-car workshop, its just another how-to for those that "choose" to undertake some maintenance.
I discussed that in my first two paragraphs. Thats how most do it simply because it is easy, but certainly not as thorough.
01-14-2013, 05:34 PM
#12
Race Car
Nice writeup Alex..... (Also helped me out as I needed to identify the pressure vs return line on my PS rack as I am pulling out the original lines for the Electric conversion).
AS for the filter, make sure the filter you use in the return line is a full flow filter, wouldn't want to see a restriction in the return not allowing the return to support the pressure side and have the PS pump cavitate.
(may or may not be an issue, just an observation.)
AS for the filter, make sure the filter you use in the return line is a full flow filter, wouldn't want to see a restriction in the return not allowing the return to support the pressure side and have the PS pump cavitate.
(may or may not be an issue, just an observation.)
