When the cold weather months come in and not uncommon to find your Power steering pump a bit more noisy than it was during the warmer months. As your engine and components go through countless heat cycles rubber begins to deteriorate and shrink, clamps that were once tight loosen up. Many of these issues can attribute to noisiness, lack of power steering, leaks and etc.

Let’s take a look at a couple of the easiest to access and remedies that we can easily do. This is also a great time to replace your power steering fluid.

Time frame

If you are just replacing the o-ring this is a very straight forward fix that shouldn’t take ore than 15 mins. Add a bit of time if you need to refill or clean up power steering fluid. The suction hose won’t take much longer but has a much higher possibility of spilling.

Tools

A few choice tools can get both of these jobs completed swiftly and with ease.

For the o-ring a socket and socket wrench, this will dispatch the bolt and allow for o-ring replacement.

Grey Pneumatic 3/8th socket set Grey pnuematic wobble socket set

The suction hose will be taken care of with pliers, the more the merrier in my mind. Make life easier with the proper set.

Knipex pliers set ATE 5 pliers set

Parts

O-ring: On the top of the power steering pump is the suction hose that brings the fluid from the reservoir into the pump. The hose connects to a metal/plastic inlet/elbow that is bolted onto the pump. This seems to be the most likely candidate of Power steering noise/issues. Over time the o-ring shrinks and hardens, when this occurs it is unable to seal out air and will allow fluid to leak out. The air being pulled into the pump will cause a lack of power steering and buzzing noise, as the air disrupts the fluid. Subaru O-ring 34439FG000 for 03-08 Foresters. This o-ring is most likely interchangable between many models, but always check for a vehicle specific part.

Left : New Subaru O-ring Right: Old O-ring You can see how much smaller and thinner the outgoing O-ring is.

Old o-ring is less of a circular ring and now a square ring. This won’t be as effective at holding fluid in and air out.

Suction hose and return hose: These two lines running from and to the Power steering reservoir, these will find that time and heat will take a toll on these two hoses. With the hardening of the hoses it will become very tough to keep the clamped connections from leaking fluid out and can allow air to be taken in, disrupting your steering. The easiest way to repair these are by replacing them, they are formed lines to help keep them away from the fans and belts. I have had a P/s line tear in my hand when removing it from the pump, showing just how bad they can get. Sunsong Power steering feed line 3403729 Sunsong power steering return hose are what I run on the Forester, I have Oem Subaru on the STi and I can’t tell any real difference.

Replacement feed hose, from the reservoir to pump. Made by Sunsong and an exact fit for much cheaper. 04-08 Fxt 02-07 Wrx/Impreza/STi. Sunsong return line not shown.

Clamps: Time makes fools of us all… and the metal clamps on the Power steering hoses are no different. Replacing these with new factory clamps is the best practice. Using worm gear clamps instead of spring clamps can cause premature damage to the hoses. Older clamps will struggle to seal older brittle/hardened hoses as they do not have the force necessary to do the job. It should also be known that even shifting the reservoir and moving the hoses can disrupt the clamps ability to seal. Subaru Power steering suction clamp 909170063

Factory clamps can lose tension over time, but are the best style when replacing old clamps.

If you need to top off your power steering fluid please check your manual or power steering cap for the appropriate fluid for your application. Both of my Subarus use Dex version three transmission fluid. You can also take a trip to your local Subaru store for a bottle of Subaru power steering fluid.

Subaru automatic transmission fluid/power steering fluid

Motul Dex three transmission fluid

Installation

We start like most under hood repairs, opening the hood and clearing out the anything in the way, i.e engine covers, alternator shrouds. With the power steering pump in our sight we can start our work.

There is an 90 degree inlet that hooks the suction line to the pump, remove the single bolt that holds it down.

If the top of your power steering pump looks like this, that o-ring is leaking.

Here is the bolt we need to remove to release the elbow and replace the hose.

With it removed you can now pull it off and remove the o-ring. Replace it with your new o-ring and apply a little dab power steering fluid to keep the seal from tearing when installed.

New and old. You can see just how heat and time have taken it’s toll on the old o-ring.

Here is another o-ring that was leaking, you can see just how squared off the normally round o-ring is.

The most likely of culprits when it comes to noisy Subaru power steering pumps.Subaru O-ring 34439FG000 Moving the line and holding it above the reservoir helps keep fluid from pouring out of it.

With the new o-ring being a bit wider and less worn down you may need to give it a small amount of force to seat it. Once it is centered and started you can use the bolt to run it completely down and complete the install. If this is your only repair to your p/s system you should do a quick bleed of the system by steering back and forth to purge any air from the system.

It is great to clean the area around the elbow and pump , this will allow to know if it begins to leak again.

This suction hose is very easy to replace, if you are replacing the o-ring this is an excellent time to replace it. Once again as above you will need to remove any shrouding above the p/s pump to open up the work area. With both clamps removed from the p/s pump and reservoir you can remove the hose. Slide the hose back on either side. You will now need to reattach the clamps and you can bleed the system.

Suction hose to power steering reservoir connection location.

Hose to pump connection. Nothing difficult here.

The best practice for bleeding the system is turning the steering wheel back and forth while not holding it in the locked position for too long. You can also elevate the front of the car to make steering the tires easier and not scrub off the tread. Check your power steering reservoir when bleeding, once the air bubbles aren’t visible you should be good.

Check your reservoir for bubbles while bleeding. When the bubbles stop appearing you are complete.

These two connections points are noted for allowing air to be sucked in or fluid to leak out. I replaced them with worm style clamps which aren’t the best but get the job done. If you are replacing your hoses using new factory clamps would be the wa… — These two connections points are noted for allowing air to be sucked in or fluid to leak out. I replaced them with worm style clamps which aren’t the best but get the job done. If you are replacing your hoses using new factory clamps would be the way to go.

These are the fairly common issues that arise with Subaru power steering pumps and how they can go from great summer pump to awful winter pump. The above fixes can keep you from prematurely replacing the entire power steering pump. Lastly, if all these checks/repairs have been completed and steering problems still persist it might be time to check your lower lines to the rack and pinion. With the rack and pinion seals being the last place to inspect for issues.