Thursday May 22 2014

What is it with my shafts?

By Paul Kaganzi

Qn: I have been driving a 1998 Toyota Spacio since 2012. I bought it from a bond at 56,000km but now the mileage is at 80,000km. It makes cracking noises from the front wheels when I am making sharp turns. My mechanic told me the “shafters” needed replacement and they were changed, unfortunately after two weeks, it happened again, this time on one side. I took it back and bought a new ones again. It started making the noises again after one day. Do you think it could be something else? Another thing is that it makes a ruffling sound when I hit the brakes for the first 400 metres when I start driving, then it fades. Please advise, thank you.
Denis Kakaire.
The “cracking” sound you describe from the front axle (wheels) of your Toyota is often associated with the grinding sound of damaged Central Velocity (CV) joints or drive shafts (locally called “shafters”).
CV joints usually fail when the rubber boot gaiters tear and let in dust, stones and water. In case yours were torn, it may be the reason why your mechanic replaced them. In case the mechanic bought used CV joints, it is necessary to confirm that they did not fail due to age.
However, there are other causes of grinding or cracking noises when turning the wheels of the front axle.
Tell your mechanic to inspect the front axle wheel hub bearings in case they are bad or loose. It will be a good idea to examine the stabiliser bar bushes and link bars (locally called Z links).

Front brake pads that are worn to metal can cause a rattling or cracking sound as you turn the front wheels. Refer to the noisy feedback (what you called ruffling) from your front brakes. Have the pads and disc rotors inspected or replaced where necessary.

Qn: I drive a Toyota Harrier with 222,500kms on the clock. In the morning the engine starts with difficulty and hesitates or stops before picking up when it warms up. What can I do?
Mugabe, Jinja.

You need to check the condition of your Toyota’s Intake Air Temperature (IAT) sensor with a computer diagnosis. The IAT is incorporated in the Mass air flow (MAF) sensor fitted on the air cleaner element housing.
These IAT and MAF sensors will measure the temperature and volume of the air coming in through the air cleaner element. The values they provide will be interpreted by the engine computer and used to determine the amount of fuel to deliver for combustion.
This is especially useful for cold starts when the computer ideally delivers more fuel for cold start enrichment hence increasing the engine revolutions which slow down as your engine warms up.
At a mileage of 222,000kms I suggest you replace your long life fuel filter attached to the fuel pump in the tank, this will improve the fuel pressure.
Check or replace your timing belt, long life iridium tipped spark plugs and ensure that your air cleaner element is clean.
Do clean your throttle potentiometer which might have carbon deposits which restrict the throttle valve movement.

I drive a Toyota Noah TownAce, with a diesel engine. Recently, I have started noticing black smoke from the exhaust pipe whenever I start the engine.

This black smoke stops immediately when the engine is running. And when I am driving at 100 km/h it comes out again and the vehicle can’t deliver enough power to exceed 100 km/h.

Qn:I always do regular engine service as advised by my mechanic but this seems not to solve this problem. What could be wrong with my engine?
Jerry Anyoli

Black smoke from your exhaust confirms the presence of an imbalanced diesel fuel air ratio in the combustion chamber of your Toyota. In your situation the fuel is delivered in more than the
permissible amounts that can be effectively burnt.
Ask your mechanic to find a fuel injector specialist who can evaluate the performance of the fuel injector nozzles. In case they are blocked by deposits, the fuel injectors will not produce a fine strong spray during delivery of the fuel. This affects the diesel compression and prevents complete combustion or burning of fuel.
This will cause delayed ignition during the start sequence or poor acceleration and performance.
Ask the technicians to check the fuel injector pump for leaks, blockage or wear and tear as it will also contribute to the above symptoms.
A very dirty or clogged air cleaner element will restrict supply of clean air which can also distort the air fuel ratio and cause black smoke and poor engine performance.