I hate intermittent faults!

Around 40-45 mph, I have experienced a worrying small oscillation in the steering wheel at a frequency of around 5Hz. It has happened maybe around ten times during my ownership.

It seems to disappear when the speed increases slightly. Despite my best efforts, I have not been able to induce it. It lasts for around 5-10 seconds. Hard acceleration, hard braking, violent weaving - no result.

The first occasion, I assumed the wheels were about to fall off. They were not.

I thought maybe the assistance was electric but, a glance under the bonnet, proves it is hydraulic (and, yes, the reservoir level is correct). It is not clear whether the steering actually judders or whether it is just the wheel.

I am no whizz on modern cars (although have '79 MGB V8, and a couple of BMC 1.5 marine diesels under rebuild) and have no clue what the cause could be.

Anyone with a similar experience please?

 

What is the MY and which engine is fitted?

How many kilometres/miles on the vehicle?

What is the age and condition of the tyres? The manufacturing date is on the sidewalls.

Has anyone attempted to inspect the front suspension and wheel balance?

 

The car is V6 diesel auto.
90,000 miles 2007.
Tyres are about 6 months old and look new.
Wheel balance was set when the tyres were replaced.

The problem is the intermittent nature of the fault and I can't invoke it. The last service was carried out by Jaguar in Cheltenham and good report received.

 

Since the issue is intermittent, note the conditions that cause it to occur such as speed, road surface, vehicle load, incline or decline, etc.

If the tyres were recently replaced, have the shop that installed them check the wheel balance and tyres for belt separation.

 

I've been unable to correlate anything with the phenomenon. As explained, I have tried a mixture of driving aggression and road differences without any obvious conclusion.

The judder is a few degrees rotation back and forth and lasts just for a few seconds. Although I am not sure, it does not seem to affect the direction the car is taking which (should be) a nonsense but because it is only small it may not be noticeable.

I will ask the tyre fitter to have a look but it is difficult to think of balance for instance coming and going. Wights slipping round the rim, tyre disintegrating and then mending itself? Don't seem possible.

Air in the power steering that moves around? The reservoir is full.

Any further suggestions are very welcome.

 

The big question: Did you have the same problem with the previous set of tires?

Most vibrations are a combination of several minor issues. There's often no single smoking gun. When all factors converge just right, you get the vibration, and then it passes.

Tires are often a major part of the equation. They may be balanced just fine, but have gone out of round. I'd suggest lifting the front end just slightly off the ground, just a fraction of an inch. Spin each tire by hand and see if the space under the tire varies by more than an 1/8" or so.

If the tires are not out of round, try swapping the front and rear tires on each side and see if that makes it any better. If so, at least one of those tires (formerly in front) needed to be rebalanced.

After that, start checking the front end for play. The ball joints take a lot of abuse. The quickest way to check is to get the front air all the way off the ground and give each tire a good shake with your hands at the top and bottom. Then repeat with your hands at the 3:00 and 9:00 positions.

 

A tyre can have a separated belt or other internal flaw that can cause intermittent issues such as what you're experiencing. It's unlikely balance weights are moving about the rim.

If the power steering pump is cavatating, there would be a distinct sound present with aerated fluid the result.

 

Also make sure that your alloy wheels are not bent and run true...

 

I'll throw something in for discussion; do our cars not have variable assist power steering? I have not had to troubleshoot one before, but road speed working independently of engine/pump speed would have me thinking about the presence of some sort of pressure regulator. More than likely an electronically controlled one monitoring wheel speed and degree of steering input. Does this sound plausible to the original poster's experience?

 

What the OP is experiencing is intermittent steering 'flutter' most likely caused by an issue with one or both front tyres, or one of the rims.

 

Yes.
I will call in at our local garage who fitted the tyres and did the balancing. In 60 years of driving, I have never experienced anything like this.

When I bought the car, the tyres were end of life and the car pulled to the left.
Replacing the tyres (they weren't cheap!) fixed that.

It's the intermittency and the inability to invoke the issue that's getting me.

 

Garage gave a thorough examination with me in attendance but found nothing.

Next time I (am allowed to!) drive, I'll try to note anything additional that may give a clue.

 

Did you not go for a drive & exhibit the problem to the mechanic?

 

As I explained, it is not something that can be induced. It just occurs with no obvious reason.

 

I've seen ball joints do this sort of thing. Have they been checked? (car off ground and pressure applied in X,Y,Z)

 

Yes, in my presence. The mechanic was quite thorough and did exactly as you have described.

The judder has happened again on the short journey into work (in my wife's hands). After it started at around 50 mph, it gradually died down as she progressed. Nothing different about the route. Weirder and weirder.

 

Did they inspect the tyres for belt separation? Sometimes the only way to tell is to dismount them from the rims and inspect them from the inside.

 

No they did not. However, wife reported a hint of the problem on her trip to work this morning so maybe it will become repeatable.

 

Did you ever lift the front end slightly off the ground and spin the tires to check for out of round?

And did you swap the front and rear tires?

See post #6 above.

 

Yes swap tires front to rear and let us know what happens.
I don't know if you have staggered rims so this might not be possible?
I think the V6 cars have all 4 rims the same?
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