I think i would hold on before changing the pump on this. Hydraulic PAS systems are generally very reliable and i would look at all other (cheaper) possibilities first.
I would probably change the belt and make totally sure it was correctly tensioned before attempting the pump itself.
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Cheaper is better, but the noise I am getting is nothing like a typical belt squeal, its more of a mechanical groan. I would be gutted if I shelled out £160 for a pump and still had the noise after though.
Also I noticed that when the engine is on, the fluid level in the reservoir drops significantly and seems to be whipped into a foam as it circulates. Is this normal?. Never noticed it before as I have never had a car with a clear fluid reservoir.
Thanks for all the advice...off to price up a drive belt.
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Hmmm, well i have driven one of these (a petrol, not a diesel) but i didn't notice anything like you describe with the PAS fluid level. On the other hand i only checked the levels with the engine off and cold.
When did this car go out of warranty? maybe a goodwill payment is possible?
If the fluid is foaming, i would think an air pocket might be in the pump somewhere.Or perhaps the fluid is being pumped back to the reservoir under too high a pressure?
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Hmm, never thought of the belt, but the belt looks fine, don't know what to do now.
My belt looked fine, but if the belts a tenner and the pumps £160, i know what i would change first.
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Can't argue with that logic bikemade, and even though the belt is 2 tenners, I will change that first.
If it doesn't sort the noise out at least there is a new belt on the car.
Car has no warranty as there was no service book when it was bought (long story why that is). I too thought the foamy fluid was odd, which again led me to point the finger at the pump, but as I said, maybe every other car does the same and I never noticed it. When the engine is off, the reservoir level is normal,the fluid goes flat and looks ok.
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It may be worth checking to see if the strainer between the rerservoir and pump inlet (if such a strainer is fitted) is clear. If there isn't free flow to the inlet side of the pump, then it is possible that the pump is cavitating - this would explain the noise and the foaming of the oil. Normally, the oil doesn't foam.
Number_Cruncher
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Unfortunately I can't check the car during the week. Its my wife's car and she doesn't get home until dark o'clock. Cavitation does sound likely especially as the fluid level drops so drastically, I imagine that it sucks air in. The level returns to "full" when the engine is off so simply adding fluid doesn't seem like an option.
I could try adding the fluid while the engine is running and the fluid level is almost nonexistent, but imagine that once engine is switched off I will have an overflowing mess on my hands.
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>>especially as the fluid level drops so drastically
I didn't realise that the level was dropping so far, so fast...
It may be worthwhile finding out where this fluid is going. For example, is it leaking into the outer parts of the rack itself, and ballooning the gaitors?, and then being swueezed back into the hydraulic system when you switch off. There (usually) isn't anywhere for the oil to go, other than round the fairly rigid circuit that it's meant too. For the level to drop, it may (must?) be going somewhere that it shouldn't.
If the level drops far enough for air to be sucked in, then, the noise and foaming are explained too. So, it may not be cavitation as such that is making the noise and foam, but simply ingestion of air.
From a statistical perspective, faulty PAS racks are common, while I have never had to replace a power steering pump on a car (trucks, yes, a few, but not cars). I'm nopt saying that your pump is *definitely* OK, just that I would look very carefully at the rack first.
Number_Cruncher
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I understand what you are saying and I will have to check the steering rack itself, though I will say I find it hard to believe that the fluid would get pumped into the gaiters, then squeezed back up to the reservoir. Not saying it couldn't happen, just that I can't get my head around such a thing happening. The £160 cost of the pump would be nothing compared to the cost of a rack+fitting (not doing that one DIY) so I am really hoping the rack is ok.
Thinking more about it, air being sucked in due to low level sounds very likely, but its the full level when off that has me baffled. The car is parked in the same area nightly and there are no fluid leaks on the drive or under the car. I was under there changing the oil in Nov and I am sure I recall hearing the noise before then.
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Just a suggestion..... if there is an air leak between the reservoir and pump inlet, this would cause the pump to cavitate (hence noise and feel) and pump air round the system (hence foam). Must be worth a look.
How this would affect the levels as you describe does not seem logical tho'.
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pmh (was peter)
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Air leaking in, should = fluid leaking out?. Will check for that too, thanks.
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I reckon NC's right. A drop of water in the PAS fluid will cause emulsification of the oil and noisy pump operation. Emulsified oil thickens and the very fine strainer within the pump can't pass enough fluid for it to operate correctly, hence the groaning noises. Try changing the PAS fluid.
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I reckon NC is on the right track too, but hope he is not right concerning a possible faulty steering rack. The fluid is definately not emulsified, it looks clear red like it should. The foaming is due to air, pretty sure of it as when the engine is off the foam dissipates and the fluid returns to normal. Just need to figure out why its doing that.
I won't be able to check the car properly until Saturday and I will be sure to update this thread with my findings.
Thanks again.
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Well its all sorted...for now...I hope.
Drained the reservoir and flushed it a couple times with fresh fluid. Filled it up to "max" and started the car, the fluid level dropped again, but not as much as before and when I switched off again it didn't return to the "max" level. I topped up and started the car again and this time it barely dropped, topped up while it was running, switched off and no overflow or anything unusual.
While the car was running I did a few lock to lock turns and noticed that when it was on full lock there was a slight bit of foam circulating through, but this eventually stopped.
The prize for best long distance tinternet diagnosis goes to p 2501 with this statement:
"If the fluid is foaming, i would think an air pocket might be in the pump somewhere."
I can't imagine what else it could be besides air trapped in the system that got compressed when the pump was turning but pushed fluid back up to full level when pump was off. Just goes to show that checking fluid levels isn't enough as that was the first thing I checked and that was fine, even though things weren't.
Thanks again for all the advice, I am sure I would have gone out and spent money on a new pump if it wasn't for the backroomers suggesting I try other things first.
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trancer,
I hope that your problem is truly fixed, but...
Air doesn't get into the system from nowhere. I fear that you may have relieved the symptoms, but perhaps not made a lasting cure.
I also hope that I am wrong in this case.
Number_Cruncher
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Very true, number cruncher, I can only hope that the level allowed to drop too low at some point prior to our ownership and that caused air to be introduced. There are no fluid leaks that I can find and if this fix only lasts for another 8 months (we've only had the car that long) then I can live with it. I can buy alot of £5 bottles of PS fluid for the cost of a new PS pump or steering rack.
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>>I can only hope that the level allowed to drop too low at some point prior to our ownership and that caused air to be introduced.
I would say thats impossible on ownership of 8 months,problem would occur soon after any air was introduced into system,so I dont think you are out of the woods yet.ie still have problems
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Steve
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I did say it was a hope 8-).
Until I see leaks, I am going to leave it. If it happens again I will try just topping up while its running as the fluid I drained out looked ok so probably didn't even need to be drained.
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