Stiff steering, probably PAS

[Go60 Jay]

Hey all,

My power steering suddenly became stiff and notchy. The fluid was dark so i replaced it with CHF 11S. Unfortunately this hasn’t solved the issue.

I’m assuming the pump needs replacing. However, I did have the wheel alignment done a couple of weeks ago and it wasn’t a great experience. Is there a possibility they’ve failed to properly tighten something and it’s worked loose, causing the steering to stiffen up? Suspension isn’t something I know much about.

If not, does anyone have any recommendations for where to go to have the PAS pump changed? If you’ve had it done, what was the cost?

Thanks,
John

[paulrog1]

I had my DB9 power steering pump reconditioned, I sent mine to these -

https://regoautoparts.com/

I sent the pump to them, they had to send it to Belgium as it is reconditioned at their sister factory there.

Cost if i remember around £200, so considerably cheaper than a new unit.

It's quite an easy job to remove it at home, aux belt off, throttle body off and 4 bolts and 2 pipes off, job done.

Edited by paulrog1 on Monday 10th June 19:04

[Go60 Jay]

Hey Paul

That’s a great help. Thank you very much. That’s probably around a £500 saving if it is the pump.

I’ve changed the belt before so being able to do that helps. Hopefully it’s as easy as your DB9. So long as the V8 doesn’t have much else to remove.

Thanks again,
John

[Go60 Jay]

I’ve just had a good look. It is pretty tight in there. On the V8V, the PAS pump is above the AC pump. On the DB9 it’s low down, under the AC pump.

Does anyone know if the PAS pump is more accessible from above or under the car?

John

[filski]

Go60 Jay said:

Hey all,

My power steering suddenly became stiff and notchy. The fluid was dark so i replaced it with CHF 11S. Unfortunately this hasn’t solved the issue.

I’m assuming the pump needs replacing. However, I did have the wheel alignment done a couple of weeks ago and it wasn’t a great experience. Is there a possibility they’ve failed to properly tighten something and it’s worked loose, causing the steering to stiffen up? Suspension isn’t something I know much about.

If not, does anyone have any recommendations for where to go to have the PAS pump changed? If you’ve had it done, what was the cost?

Thanks,
John

I don't have much knowledge on how AM pumps work exactly but I suspect if it's anything like a normal hydro one then I would say in my experience with JDM cars check the following.

1. Belt tension ( although I think you noted its tight)

2. does the pump make whining noise when turning the wheels? (Could suggest pump possibly at fault or air in the system)

3. When you changed fluid, if you take the cap off can u see pas bubling at all when turning the wheels or does it look like what is best described as boiling jam 🤣? (This could mean air in the system that would stiffen the steering feel)

4. For any of the above I would say see if there is a bleeding sequence for pas, I'm not sure if AM is similar but on Jap cars you tend to jack the front of the car up and turn full lock to lock few times until bubbling stops. Now if you doing it for more than 20 times then it is safe to say that air is getting into the system while in operation so you have to sadly check all hoses and any leaks. Note that in some instances it could be an air getting in without a visible leak.

I would check the above before getting a PAS pump reconditioned. Again I'm not sure what they are built like but it also could be an o ring inside a pump that have perished.

Lastly in terms of alignments, this shouldn't have caused steering to fail as really they would only adjust your tie rods once the steering wheel is centered.

Good luck

Fil

[Go60 Jay]

Hi Fil,

I’ve gone through the process to eliminate air bubbles and still no better.

Even if it is just a perished O ring, if the pump needs to come off, then it may as well be sent to be rebuilt. If it’s not really a job that can be done at home, then I’ll have to get it done at a specialist. Although I suspect they’ll want a new pump fitted, rather than wait for it to be sent off and rebuilt.

Thanks for your thoughts.

Kind regards,
John

[filski]

Hi John,

No worries I didn't want to assume thus made all the notes that I had to go through I too battled with pas for a year doing all sorts and it ended up being a notch in the return pipe that allowed the air in.

Agreed about sending for recon if you have eliminated the above, especially if it's having to come off anyway.

Hope resolves the issue as I can confirm driving without pas is too much of a fore arm work out.

Fil

[paulrog1]

Go60 Jay said:

I’ve just had a good look. It is pretty tight in there. On the V8V, the PAS pump is above the AC pump. On the DB9 it’s low down, under the AC pump.

Does anyone know if the PAS pump is more accessible from above or under the car?

John

Sorry I don't know how difficult it is to remove one from a V8V but on the V12 engines the above info is not correct.
The pump is at the top of the engine on the righthand side (secondary bank) above the water pump and below the throttle body

[Go60 Jay]

Hi Paul,

Yeah you’re spot on. I’m not sure what layout I was looking at where they were switched. Maybe an old Aston engine layout. Either way, you’re right.

Frustratingly I’m away working for a week from tomorrow, so I won’t be able to see if I can access it from below or if I can squeeze in from above.

Thanks for the help, gents.

[Go60 Jay]

Just a small update.

So I’ve changed the pump. I was going to use the company that was kindly suggested above to recondition my old pump. Sadly they went in to receivership 3 days before I took the pump out. I bought a new one from HWM ASTON in Walton On Thames. They were very helpful and even knocked off some money.

I’ve fitted the new pump, which wasn’t as difficult as I had expected. I’ll do a “how to guide, soon.Unfortunately it hasn’t solved the problem. My biggest fear is the steering rack may need replacing. They cost about 4k plus they’ll no doubt cost a fortune to fit.

I took it to a garage I really trust and have always been really good to me. They said they don’t think it’s the rack and can’t see or think of a reason why it would be. Other than a possible blockage. They put in an additive FOC to help the system. It’s booked in for a service in August. They’ll give the system a full and proper flush through, rather than just the siphon technique I used, in case there is something stuck in the rack.

They did mention the possibility of a steering module that senses you turning the wheel and then gives the assistance. Does anyone have any experience or knowledge of this?

Thanks,
John

[Mogul]

I don’t know about Astons but does it have a ZF rack?

The “Servotronic” racks have a solenoid that varies the hydraulic assistance based on a speed and if the car sees that you are driving fast, assistance is minimised etc.

You can imagine that even if the speed sensor is providing the right signal, if the actual servotronic ‘solenoid’ is on the fritz then it is possible that it fails in the minimum hydraulic power assistance setting…

https://www.audiworld.com/forums/attachments/a8-s8...


https://www.ebay.co.uk/itm/266427049485?mkcid=16&a...

[Go60 Jay]

Hi mogul,

That was mentioned, but want to check if it’s the case on the V8 vantage. They think it might be something on the DB9 but may have been removed from from the Vantage. Possibly depending on the year.

[TR-Spider]

I'm quite sure the V8V does not have the speed sensitivity valve (some V12 have).

When you changed the fluid, did you add Lubrizol?

see this for details:
https://www.youtube.com/watch?v=786H4d_ht40

[Genie Chaser]

May be worth remove the steering column shafts from the rack. There is a uj, have seen one or two in the past partially siezed causing tight steering. Just a thought.

[Go60 Jay]

Thanks TR, I thought the same but then I wasn’t sure if it were the case on later models or the S. I know a number of things on the V12 are on the S. cheers.

[Go60 Jay]

Genie,

What’s a UJ? I’m guessing it’s a joint? Thank you.

John

[trevalvole]

Go60 Jay said:

My power steering suddenly became stiff and notchy.

I think the notchy bit will be when the pump is pumping air rather than fluid and thus providing no assistance. I had something similar on a SEAT Ibiza many years ago. A proper diagnosis is called for, I think.

[Go60 Jay]

Sorry TR,

I for got to say, the garage added Lubrizol for me.

Trevavole, It’s going in for a service so hopefully a full and proper diagnosis then.

[Genie Chaser]

Go60 Jay said:

Genie,

What’s a UJ? I’m guessing it’s a joint? Thank you.

John

It's the universal joint at the bottom of the column where it attached to the rack. If you do disconnect it ensure the steering lock is on so as not to unwind the srs clock spring.

[Go60 Jay]

Damn it, universal was totally my guess, lol.

The stiff steering was sudden, as if the car had stalled so I’m guessing it’s more of a failure. But checking and lubing it up can’t hurt.

Thanks.