S

Scotzman

New Member
Hi Folks, got a little puzzler.

A small inconsistent whurr, whurr, whurr noise when on hard lock has turned into a consistent whurr, whurr, whurr noise at any time the steering is not pointing straight.

There is now a "smell" of heat after using the car for any more that a short run.

The steering itself does not feel slack or affected in anyway.

I have had a look and can't see anything obvious underneath, so dropped it into my mates garage and had it up on the ramps and he couldn't see anything either.

Brakes, bearings, rubbers and bushes have all been checked and nothing obvious appears wrong. I have also recently changed and checked the engine and gearbox oil and both are fine.

Any help or pointers would be appreciated.

Dougie
 
Scotzman said:
Hi Folks, got a little puzzler.

A small inconsistent whurr, whurr, whurr noise when on hard lock has turned into a consistent whurr, whurr, whurr noise at any time the steering is not pointing straight.

There is now a "smell" of heat after using the car for any more that a short run.

The steering itself does not feel slack or affected in anyway.

I have had a look and can't see anything obvious underneath, so dropped it into my mates garage and had it up on the ramps and he couldn't see anything either.

Brakes, bearings, rubbers and bushes have all been checked and nothing obvious appears wrong. I have also recently changed and checked the engine and gearbox oil and both are fine.

Any help or pointers would be appreciated.

Dougie
Click to expand...

Is the power steering pump getting hot?
 
Is the PAS fluid level correct?

Has it been changed recently??

Any Hydraulic fluid will lose viscosity and other mechanical properties after a while a d be no better than water before long!
 
Hi guys

thanks for the suggestions, unfortunately I wont be able to have a look at her until next weekend. Will let you know how I get on.

Cheers

Dougie
 
Hi Folks,

Managed to get a look today.

1) Power Steering Pump - Assuming that this is the aluminium block that the reservoir sits on, then no, its not any hotter than I would expect sitting close to the exhaust manifold.

2) Belt Tensioner seems to be rotating fine, all front pulleys seem to be working fine.

3) PS Reservoir is on the minimum, but by no means empty. will top up today unless a full change is required. Not sure how to check the viscosity, but would this really account for the noise I am hearing?

I actually thought as the "Whurr Whurr Whurr" is speed affected (slower whurrs when going slower) it must have something to do with the wheel rotation, but having checked most of things that rotate (with limited knowledge) I am a little lost. Can't replicate the noise unless driving it.

Even thought it could have been the axle or drives-haft, but can't understand why the noise would be related to turning the wheel?

There also seems no way to pinpoint the "heat" origination, as to get it that hot, it has been driven so the block and the exhaust are also very hot anyway.

Any other suggestions would be most welcome!

Thanks

Dougie
 
You need to be more explicit in your description. Does the noise come when you turn the steering with the car stationary? Or does it come when you turn the steering whilst moving and increase the faster you go?
 
Hi Wammers

The noise is not present when the car is stationary and the steering wheel turned.

It does however quicken in line with the car's speed, so if I am going through a long bend on a road at 40, the noise is repeated quicker than I would experience going through the same bend at 30.

Hope this helps

Doug
 
Scotzman said:
Hi Wammers

The noise is not present when the car is stationary and the steering wheel turned.

It does however quicken in line with the car's speed, so if I am going through a long bend on a road at 40, the noise is repeated quicker than I would experience going through the same bend at 30.

Hope this helps

Doug
Click to expand...

Sounds like a wheel bearing.
 
wammers said:
Sounds like a wheel bearing.
Click to expand...
+1...now he has added more information, I would concur.

This is why being as descriptive as possible is helpful...!! Yes, my posts may be long and drawn out, but 9/10 times I will try and be as descriptive with my problem as possible...

And to answer your query regards Fluid Viscosity and the noise....

The PAS Pump is a Hydraulic pump designed to move fluid at pressure of a certain thickness....as the fluid ages, the properties of it changes along with the fluid viscosity, density and compressibility.

Hydraulic fluid by design should not be compressible as this is how Hydraulic power is transmitted...if the fluid is old and knackered, it starts to be able to be compressed and/or thins...the pump then starts to potentially cavitate making odd noises..this can warm the fluid up to beyond its usual operating point and this then further thins the fluid leading to more cavitation, less power transmission through it being able to be further compressed and the fluid starts to over heat and the properties in it are changed further from the design point....sometimes old fluid can smell burnt where it has overheated to the point of property change.

So yes, old tired and thinning fluid can cause noises as the pump struggles to move the fluid and transmit hydraulic power!
 
that was my initial thoughts, but it has been checked at my mates garage and its not that, or seemingly anything related to the mechanical turning of the wheel.

Bearing in mind, the noise is only generated when the steering is off centre, and my experience is that a bearing will grind regardless of the direction of the wheel....well it certainly did just before my front wheel nearly fell off my merc :)
 
thanks guys for the input, and comments.

I did mention in my original post that the car has been in the garage and the brakes, bearings, rubbers and bushes have all been checked, and they are fine.

I also mentioned in an earlier post, albeit not the original that the noise is relative to the speed of the car.

Therefore I thought it might have been something more unique to the P38 rather than a run of the mill mechanical failure.

I also said that the steering itself felt unaffected, and would have thought if the oil had lost viscosity, it would have affected the steering itself, although I will look at replacing the Steering Fluid at the weekend.

But if there are any other suggestions, I would happily take them on-board.

Thanks in advance

Dougie
 
Saint.V8 said:
+1...now he has added more information, I would concur.

This is why being as descriptive as possible is helpful...!! Yes, my posts may be long and drawn out, but 9/10 times I will try and be as descriptive with my problem as possible...

And to answer your query regards Fluid Viscosity and the noise....

The PAS Pump is a Hydraulic pump designed to move fluid at pressure of a certain thickness....as the fluid ages, the properties of it changes along with the fluid viscosity, density and compressibility.

Hydraulic fluid by design should not be compressible as this is how Hydraulic power is transmitted...if the fluid is old and knackered, it starts to be able to be compressed and/or thins...the pump then starts to potentially cavitate making odd noises..this can warm the fluid up to beyond its usual operating point and this then further thins the fluid leading to more cavitation, less power transmission through it being able to be further compressed and the fluid starts to over heat and the properties in it are changed further from the design point....sometimes old fluid can smell burnt where it has overheated to the point of property change.

So yes, old tired and thinning fluid can cause noises as the pump struggles to move the fluid and transmit hydraulic power!
Click to expand...

Just out of interest how would one go about changing the ps fluid.
 
Saint.V8 said:
+1...now he has added more information, I would concur.

This is why being as descriptive as possible is helpful...!! Yes, my posts may be long and drawn out, but 9/10 times I will try and be as descriptive with my problem as possible...

And to answer your query regards Fluid Viscosity and the noise....

The PAS Pump is a Hydraulic pump designed to move fluid at pressure of a certain thickness....as the fluid ages, the properties of it changes along with the fluid viscosity, density and compressibility.

Hydraulic fluid by design should not be compressible as this is how Hydraulic power is transmitted...if the fluid is old and knackered, it starts to be able to be compressed and/or thins...the pump then starts to potentially cavitate making odd noises..this can warm the fluid up to beyond its usual operating point and this then further thins the fluid leading to more cavitation, less power transmission through it being able to be further compressed and the fluid starts to over heat and the properties in it are changed further from the design point....sometimes old fluid can smell burnt where it has overheated to the point of property change.

So yes, old tired and thinning fluid can cause noises as the pump struggles to move the fluid and transmit hydraulic power!
Click to expand...

He says it isn't, so who am i to argue? But i'll bet it is. :D:D:D There is far more load on the power steering pump stationary than when moving so i would rule that out. :);)
 
Last edited:
Hey Wammers

You might be right, and if you are...I will drop a post on with a picture of me sitting at the side of the road minus a wheel :D

But there is no heat build up on the wheel or the hub/axle....wish it was...would be so simple!

Dougie
 
Scotzman said:
Hey Wammers

You might be right, and if you are...I will drop a post on with a picture of me sitting at the side of the road minus a wheel :D

But there is no heat build up on the wheel or the hub/axle....wish it was...would be so simple!

Dougie
Click to expand...

The design of the wheel bearings is such that it is almost impossible to tell by hand if there is any roughness in the early stages of failure, you are turning a wheel a drive shaft and a differential. Only if the bearing was really bad could it be detected by that method. However if the bearing is gored it will make a noise when trust is applied to it as in cornering. It may not make any noticeable noise in a straight line.
 
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