thats a good idea, if you find the solution you will not ever buy a new pump again
i would have done the same as i am very curious and would love to find out what actually causes the pump failure and what goes wrong..
I've seen some threads re: how to "clean" the dust and then some on what's necessary to truly rebuild it... our facility manager has some good suggestions that I'll pursue. If it works as expected (hoped) I will definitely post up - the $500 price for the new pump almost ruined my day, especially when the problem will probably arise again...
I suggest you try cleaning out the dust from the motor as a first step. It has worked for me.
I have not read any suggestions that the problem with these pumps is associated with the mechanical components or the drive motor. I suspect the problem is being caused by the control module. The typical symptoms of a noisy pump could well be control module operating the pump at high speed and a continuously running pump could also be a faulty control module.
As the control module is right next to the motor it seems possible the highly conducting dust (copper and graphite) from the motor brushes and commutator would cause the control module to go faulty or not behave as designed to.
It would really good if someone could get bottom of why these pumps fails prematurely.
The power steering pump in my wifes mini packed in, I couldn't believe the the price of a new item so I thought I could have a look inside.
I am a qualified electronics engineer with a motorcycle parts business.
So here in steps is how to dismantle it, this isn't ment for novices but mechanics or other engineers.
Remove the pump from the car
Remove the fitting brackets and fluid pump from the end of the motor.
Remove the screws holding the motor body together and seperate.
I had to drift out the shaft from the brushes section.
So why did you motor fail, well the motor is fitted with carbon brushes,
over time the carbon brushes wear, the carbon then flies about inside.
The motor is fitted with a computer system, (lots of chips) the carbon dust settles on the chips (which should be sealed with a laquer but arn't).
The carbon is a conductor so it totaly screws up the computer, as dust it is also a poor conductor so tends to disrupt the operation rather than totaly destroying them.
all you have to do is wash the carbon off the chips with a little brake cleaner and allow to dry. I removed the brush assembly but to do this you have to cut the link coils between the computer at the rear of the motor with the brushes. When refitting these need to be resoldered onto the original positions, these are originaly spot welded.
Now that I know what the fault problem is, it may be possible to just spray the brake cleaner through one of the holes on the brush mounting plate, but you risk not removing all the carbon, too little fluid and you leave carbon, too much fluid and you risk drying out the end bearing.
If anyone would like some photo's of the job, let me know.
6 months on, the motor is faultless.
Last edited by pulsey; Feb 3rd, 2010 at 09:07 PM.
Reason: typo error
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Hi Alan, i was always wondering why the pump fails and you have found it, i have to say this is amazing and thank you for sharing this useful information.
a few photos would be great if you can please.
The first shows the brush plate after I have refitted and soldered the 4 connections.
second is under the fluid pump, you have to remove the circlip and drift out this shaft.
So split the case first then remove the circlip and drift out the shaft, get ready to catch the armature assy and don't let it drop.
third shown the armature (oposite end from the circlip) after removing case
last shows the computer after cleaning, the carbon dust is very sticky and can't be blown or brushed off, you need some solvent but keep it away from the bush bearing in the centre
Last edited by pulsey; Feb 3rd, 2010 at 08:54 PM.
Reason: adding more information
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Excellent, there are some photos on TotalMini (see link below) but I think yours is the first to detail how to clean and access the electronics/computer part of the pump in detail, which often seems to cause the problems. I will have a spare pump to rebuild in the next couple of weeks so this will be a useful reference. Thanks again for sharing.
WISH i seen this post sooner only just replaced my power steering pump with a reconditioned pump from BAA Reman @ £200! If I had any tell tale signs that the pump was going to break I would have taken it out and cleaned up as best I could to save on buying a new one.
Im about to use that bba-reman place but only because there is a leak on the PS pump. I hear a moaning noise when turning the wheel but its mainly because the fluid has been low. I would prefer to try and fix the pump from leaking if at all possible, anyboby have any ideas of where the fluid could be coming from? Havent totally pulled it out yet but should have it out this weekend.
this is the great thing about the web a simple search and all the answers. Alan thanks for the detailed instructions on disassembly and cleaning have already had the pump apart on my 03 cooper once found one of the main terminals had corroded and snapped had repaired that and cleaned the stator/rotor section of the motor, that area was full of carbon dust, but had not removed the brush plate and cleaned the control boards. have refitted to the car and the pump runs initially for a few miles but then stops or operates intermittently. I'm going to remove again strip and clean properly will post the results when the job is done.
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You need to gently tap the end of the shaft taking care not to damage the key that drives the pump. It's a long time since I dismantled my pump, I don't remember it being particularly difficult to drive the shaft through the pump end plate.
Last edited by ratherbewindsurfing; May 6th, 2010 at 11:11 PM.
I sat the motor casing over a large vice with the armature dangling, then with a few taps on the shaft the armature fell free, get ready to catch it. you should place a piece of wood over the shaft if it's tight.
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