Why does my steering wheel vibrate?

I have a Toyota Kluger that was made in 2003, it has sent me nuts. Whenever I get to speed 80kmph the steering starts to vibrate and seems to lose balance, we have done wheel alignment, balancing and seen mechanics but we have never understood what the problem is. What should we do?
Jerusha Ariko

In most cases steering wheel vibration at low speeds between 30-70kph will be caused by issues to do with the wheels such as tyre pressure, damaged rims, poorly balanced wheels and faulty wheel alignment. Apparently these are the checks you have exhaustively done. I wonder whether you have checked the condition of the tyre walls and the tyre tread surface. If your tyres are unevenly worn out or have bulging side walls, this will cause steering vibration or wobble, even at high speeds beyond 70kph. You need to have your steering linkage (tie rod ends and rack ends) carefully examined. Do have the vehicle suspension looked at to check for damaged or worn out bushing (bushes) and ball joints. Particular attention should be paid to the upper and lower control arms and stabiliser link bars (z links). These components support the wheel hub assembly on which your wheels are mounted. It will be necessary to confirm that the wheel hub bearings are not worn out because they can cause a wheel wobble.

I have a Noah Super Extra Limo 2000 model. I used to experience vibrations or shaking when I accelerate past 40km/hr, and when braking. I was advised that my wheels had worn out and I had all of
them replaced with new ones and wheel balancing/alignment done. Things
improved a bit but the car would still shake when braking at high speeds. I reported to my mechanic and he told me that he needed to “sharpen” the brake disks so that there is even compression by the brake pads. I was planning to take the van to him this weekend, but the symptoms seem to have cleared after nothing being done, but I am still worried on what to do because I am not worried that the symptoms might surface again very soon. Please advise
E Kasule.

Damaged tyres, wheel rims or warped wheel disc rotors with ridges will cause the kind of vibration or feedback you describe,while braking or accelerating at low speeds. That is the reason why your mechanic correctly suggested that you replace the tyres and carry wheel alignment and balancing. Perhaps that explains the improvement. If the wheel disc rotors are warped with ridges, the proposal to skim them with a lathe machine will help.

However, this repair action is subject to the wheel discs having the recommended width. If they are worn out beyond the limit, skimming off a layer of metal will prevent effective braking as the pads will not have sufficient braking surface. Damaged, loose or worn out suspension components can cause vibration or shaking feedback when you accelerate beyond 40 kph. The suspension supports the wheel hub assemblies, therefore when it fails, the rotational force caused by the speeding vehicle is not harnessed tightly which results into wobble and vibration. Ask your mechanic to scrutinise the condition of your entire suspension.

My problem is the that my BMW X5 made in 2003 with a diesel engine has developed a starting problem. It has a hard start and also reduces speed especially when you want to over-take on a high way. This started after bad fuel at a certain petrol station in Ntinda last year and it has persisted despite replacement of parts such as fuel pump, injector pump, high pressure sensor, and finally, the ECU! What could be the problem? This is driving me nuts!
Davis Ampwera

Your E53 BMW X5 should have had a computer diagnostic test before dismantling or replacing any parts. In case you have a diagnostic report, do share the fault codes reported and I will be able to help you faster. I am also interested in knowing the mileage covered. I did not see an indication that your technicians replaced the fuel filter, checked the fuel injectors or tested the glow plug performance. These three components can cause the hard start and poor acceleration if they are faulty. There are a couple other factors, besides fuel supply, that can cause the symptoms you describe.

On your E53 it is important to establish that there is no vacuum leak or low charge pressure due to the turbo failure. Failure to accelerate can happen if your turbo is damaged or its performance compromised by a leaking vacuum hose. Signs of turbo failure include oil leaking through damaged seals and worn out bearings. Noise from the turbo during engine run will suggest damaged bearings or a broken shaft. The ignition system is supported by the crankshaft position sensor, intake air temperature or mass air flow sensors. They must be in a good working condition because they regulate fuel delivery during and after cold starts. The computer diagnosis would tell if they are faulty.