Do not use short cuts, you need to buy an expensive radiator

Qn: I drive a Mercedes E200 1997 model. The radiator recently developed a leak and my mechanic says I have to replace it. The mechanic is suggesting that we buy an expensive radiator with an oil cooler. Do I need this sort of radiator or a simple one from Kisekka’s market will do?
Barbara Akong

Ans. Your mechanic is right. You need to buy an expensive radiator with an attached oil cooler unit. Your Mercedes must be equipped with an automatic transmission. This kind of gearbox is cooled by running its transmission fluid (ATF) through a special chamber attached to the engine cooling radiator and back to the gearbox.

Elimination of the radiator’s cooling role by replacing it with one for a manual transmission will cause rapid and severe damage to this gearbox. If you cannot afford a new radiator your only recommended option is to buy a quality used but correct radiator from the vendors of used parts in town. You will need to rely on your mechanic to help you find a good radiator.
Do not forget to renew the coolant fluid in your cooling system with radiator coolant - not plain water, as this will damage the replacement radiator, water pump and other components of the cooling system.

QN:I have been reading your car repair advice. My Pajero, with a 4M40 engine, is overheating. This started after my mechanics overhauled the engine. We have cleaned the radiator, replaced its top, checked the radiator fan and removed the thermostat but the car is still overheating. Can you advise me on what to do?
Siraje
Ans: I can understand your frustration, having to deal with an overheating engine after you have just spent loads of money to overhaul it. Assuming all the components of the cooling system you mentioned above are okay, you should confirm with your mechanic if he inspected the condition of the water pump during engine overhaul.
(The performance of the water pump can also be assessed by looking at the pressure in the coolant return hose towards the radiator or looking out for leaking points or a strange noise while the engine runs or while you are removing it and inspecting its internal flange). If the answer is in the affirmative, then you need to ask him to review the condition of the cylinder head.

I presume your engine overhaul gasket kit included a cylinder head gasket and you replaced the old one. Ask the mechanic to remove the cylinder head and have it checked by an engine block and cylinder head machinist.

This technician will measure the surface of the cylinder head with a special tool to determine that it is not too warped or deformed to allow leakage of hot coolant from the engine. In case the cylinder head is deformed you can resurface it or replace it with a good used one. That should fix your problem.

QN:Recently, my 2007 Mercedes Benz E200 steering was replaced by a technician. Thereafter the horn stopped working and the airbag fault light displayed on the instrument panel. Are these two problems connected? What can I ask the mechanic to check, is it expensive to repair?
Doris Mukasa.
Your Mercedes Benz steering spiral contact cable located under the airbag in your steering boss is damaged. The contact cable connects the driver airbag to the SRS system and the steering horn switches to the horns.

The contact cable may have been damaged when replacing the steering rack. The technician should ensure that the steering boss is held in one straight position to avoid turning it beyond the limit and stretching the spiral cable beyond its limit. A new one does not cost a fortune and it will restore normal operation of your horn and driver airbag system.

QN:I drive a 2002 Land Rover Freelander which I have had for three years and it has covered 120,000 miles on the clock. Recently it started making a rumbling and deep humming noise on one of the rear wheels. We cannot seem to find the cause of the problem. My mechanic suggested the wheel bearing but you cannot remove it and check it as it is not replaceable once removed. How can we confirm cause of noise?
Raphael Mwambu

The most probable cause of the sound you describe on your Land Rover is the wheel hub bearing. Judging from the mileage you have covered in ‘miles’ (equivalent of 200,000 kms) it will not be a surprise that your hub bearings are the culprit or cause of this noise.
Your mechanic is on the right trail and he is spot on about the fact that wheel hubs cannot be replaced once removed.
This is because they are snugly or tightly fitted and have to be pressed by a machine to remove them. What the mechanic ought to do is jack up the car and run the tyres to confirm which one makes the noise described.

If the noise is from the rear axle it might be a good idea to replace both hub bearings as the good one will certainly fail soon due to the mileage factor.

This saves you paying the repair fitting cost twice and the downtime when the car is in the garage. You need to consult a Land Rover dealer with your car details to identify the correct wheel hub bearings.
Some models have a bearing with an anti-lock brake system (ABS) reluctor ring embedded in it. Replacement of this kind of bearing with a non-ABS type will switch off the ABS system and prevent the odometer from reading the wheel speed.
Once you have the correct parts your mechanic should replace them and your car will be fine.

I have a Toyota Corolla 110. It has now covered 220,000kms and it is sound. How can I improve its performance or should I sell it?
Martin Eyodu
At 220,000kms, your Corolla 110 is almost getting vintage value. You can improve its performance by overhauling the front and rear suspension from bushes, tie rod ends, to shock absorbers.
Drain and renew all the engine and transmission fluids from oil, gearbox fluid, radiator coolant, steering fluid and brake fluid.
Change the spark plugs, air filter, fuel filter, high tension leads and consider replacing the battery too if necessary.
You may need to replace your brake pads and discs as well as your tyres. You also need to replace the timing belt, tensioner and roller.
You may need a new coat of paint on top to finish off the good work underneath.
That will improve the Corolla performance and cost you about Shs3m to Shs4m. So you can either spend more on this Corolla or use the same amount to upgrade to a car with lower mileage.

What do these buttons ect-s pwr and ect-s manu mean and do on automatic transmission Toyota corona ST 190?
Daniel Kaweesa.
That is the button that changes the shift points and hold points on your transmission gear shifting.
ECT pwr (power) is for more aggressive driving. In the power mode the shift points allow you to stay in lower gears a little longer.
In the power mode, the transmission down shifts quicker and holds the gear longer in the rpm band before shifting to the next higher gear this enables you to maintain high engine revolutions per minute.
In this shifting mode, your fuel consumption is higher as you keep your engine revolutions high.
The ‘manu’ mode is for normal driving and allows you to enjoy fuel economy with slower gear down shifts and faster gear up shifts.

The fourth cylinder is misfiring on my 1996 Mercedes Benz C240. How do I fix it?
Ismail Lugolobi
Ans. Can you ask your Mercedes technician to check the condition of the spark plug for the fourth cylinder? If the spark plug is okay, check the resistance of number four cylinder ignition coil and the condition of its suppressor cable.
Confirm that the circuit for the fuel injector to cylinder four has continuity and the injector is not blocked. Rectify what is faulty and you will eliminate the misfire.

My Toyota Corolla Ipsum is making rattling noise near the front wheels when I drive on a bad road. Could it be my shock absorbers? Harriet
Rattling noises near the front axle or wheels suggests a problem with the steering linkage.
Before you ask your mechanic to replace your shock absorbers, I suggest you check the tie rod ends, rack ends and stabiliser link bars.
Those are likely to be the cause of that distinct rattle near your front wheels.
New replacements are available at any Toyota parts shop downtown.