Power steering pump noise

Dieselyeti

Junior Member
31
0
6
Trumbull CT
Howdy all,

Just tonight the PS pump started making a racket - you know the howling noise when you move the wheel? I checked the fluid as it's the same sound your hear when the fluid is very low and it was right below the Min mark on the reservoir. I didn't think that would make a difference but added Mercon fluid to top it and the noise is unchanged. I saw some intermittent fluid leaks behind my car in the parking lot but am not sure it was from my car. Any way, my question is how big a PITA is it to swap out the PS pump? I had no problems replacing the starter last summer, so I am handy with a wrench. Could there be any steering rack involvement, or does this sound more like a bad pump bearing?
 

Town

Senior Member
4,398
126
63
Ottawa Ontario Canada
I think he has a 2008 model.

Since the pump starts to make a noise when the wheel is turned it may be an overloading issue with the belt. Good chance the belt is slipping due to age/wear or the tensioner has weakened. You can check the tensioner with a breaker bar; it should need a lot of force to release tension on the belt. If the belt has not been replaced then it is time, they only last 10 years at most regardless of mileage. We have the procedure to replace the serpentine belt in our Tech forum here: Town Car serpentine accessory drive belt replacement a pdf version of the 2007 model procedures is in post #5.

The power steering takes Mercon V fluid; Mercon is an old discontinued trans fluid that was also used in power steering of older models. There is a lot of capacity in the fluid reservoir so a slightly low level is not an issue although it should be topped up. Cavitation of the oil in the pump at cold temperatures is a fairly normal occurrence for older models. Merrcon V should have solved that problem.

The diagnostics do not give noise as a symptom of a faulty pump, so do you have full power steering at parking speed. A faulty bearing would make noise all the time the engine is running.

If you feel the problem is in the pump, attached are the procedures to replace it.
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Dieselyeti

Junior Member
31
0
6
Trumbull CT
I think he has a 2008 model.

Since the pump starts to make a noise when the wheel is turned it may be an overloading issue with the belt. Good chance the belt is slipping due to age/wear or the tensioner has weakened. You can check the tensioner with a breaker bar; it should need a lot of force to release tension on the belt. If the belt has not been replaced then it is time, they only last 10 years at most regardless of mileage. We have the procedure to replace the serpentine belt in our Tech forum here: Town Car serpentine accessory drive belt replacement a pdf version of the 2007 model procedures is in post #5.

The power steering takes Mercon V fluid; Mercon is an old discontinued trans fluid that was also used in power steering of older models. There is a lot of capacity in the fluid reservoir so a slightly low level is not an issue although it should be topped up. Cavitation of the oil in the pump at cold temperatures is a fairly normal occurrence for older models. Merrcon V should have solved that problem.

The diagnostics do not give noise as a symptom of a faulty pump, so do you have full power steering at parking speed. A faulty bearing would make noise all the time the engine is running.

If you feel the problem is in the pump, attached are the procedures to replace it.
Yep, it's a 2008 with 67k miles. The tensioner and serpentine belt were replaced in 2017 so I can prob rule that out. The fluid I used was Prestone which is ATF and Mercon compatible according to the bottle. The pump is fairly quiet at idle, but moving the wheel when stationary results in a loud moan from the pump and I can feel the steering boost cut in & out intermittently. I hope there's no involvement with the steering rack as that will seriously bump the cost to fix. I already have a quote of $500 for the pump replacement; after looking at the pdfs it's not something I'd want to tackle myself. (don't have the special tools anyway)
 

Town

Senior Member
4,398
126
63
Ottawa Ontario Canada
The pressure cutting in and out may be air in the system too. Have you jacked up the front off the ground and with engine off turned the steering wheel from lock to lock. This will identify any problem in rack or the steering column lower universal or steering joints. I will see if i can find any diagnostics for inconsistant pressure. Suspension switch needs to be off for any lifting of car.
 

wolf_walker

Junior Member
105
13
18
Really need the wheels off the ground to evaluate turning the wheel like that.

Town, are these known to somehow get air into the fluid over time or just when there is a leak somewhere? I notice the FSM suggests the use of a vacuum bleeding procedure rather than just cranking the wheel lock to lock like most cars. I purchased the vacuum adaptor awhile ago but the weather has been fowl and I haven't used it yet. I plan to flush mine and do the vacuum bleeding procedure next time I get it on the lift to see if it'll hush up a bit. It's slightly audible around town on a good day and sounds like an electric car on a bad one, steering action seems fine other than a sort of almost wander at highway speeds that I suspect is something else.
______________________________
 

Town

Senior Member
4,398
126
63
Ottawa Ontario Canada
Really need the wheels off the ground to evaluate turning the wheel like that.

Town, are these known to somehow get air into the fluid over time or just when there is a leak somewhere? I notice the FSM suggests the use of a vacuum bleeding procedure rather than just cranking the wheel lock to lock like most cars. I purchased the vacuum adaptor awhile ago but the weather has been fowl and I haven't used it yet. I plan to flush mine and do the vacuum bleeding procedure next time I get it on the lift to see if it'll hush up a bit. It's slightly audible around town on a good day and sounds like an electric car on a bad one, steering action seems fine other than a sort of almost wander at highway speeds that I suspect is something else.
Yes, I thought that is what I was proposing that the wheels be lifted off the ground?

Attached is the power steering air purge procedure (system purging document) using the vaccuum pump. Also attached is the air purging procedure without the pump (system flushing document) that I normally use, but this procedure has warnings that you can draw air into the system if not done correctly, so I had it done at my dealer.
 

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