Why does my engine coolant leak?

The reason your engine coolant will leak is because the water pump can fail when its flange breaks down due to corrosion damage and poor lubrication from old coolant fluid. PHOTO BY PAUL KAGANZI

Dear Paul, thank you for the car repair solutions you share with us. I read your page in the Daily Monitor every Thursday and it has helped me come to grips with car maintenance. I recently bought a Toyota Camry.
The car has been running well until it started leaking engine coolant under one of the belt pulleys and making a strange noise in the front of the engine.
I have parked it, before visiting my mechanic I want to get your opinion. Aggrey.

Hello Aggrey, your car may have a damaged engine water pump. The water pump is belt driven and helps to keep coolant moving around the engine.
The water pump can fail when it’s flange breaks down due to corrosion damage and poor lubrication from aged coolant fluid. Signs of water pump failure include leaking coolant, a noisy water pump flange and overheating due to poor coolant flow.
Your mechanic should be able to confirm my remote diagnosis very easily. Replacement of the water pump should be with a genuine Toyota part. Renew all the coolant fluid thereafter.

Hi Paul, my Toyota RAV4 model 2000 upper engine makes noise like an old sewing machine when I start it in the morning or after parking for a while. Once in a while, the oil warning light or check engine shows briefly. My service bay mechanic says the engine oil level on the dipstick is okay. However, I have noticed some loss of power and the frequent check engine light. What should I do. Kasule. R

Hello Mr. Kasule, your 2000 model RAV4 has an ACA21 petrol engine with a Variable Valve Timing (VVTi) double overhead camshaft (DOHC) valve train. This efficient valve train system is very sensitive to prompt delivery of good quality engine oil. An engine can experience a restriction of oil supply due to delay to change engine oil or use of low grade lubricants (which cause engine sludge). In the long-term, this results in mechanical damage and the sort of noise you describe. Often the noise will indicate wear of engine bearings or damage of valves, camshaft, crankshaft or the timing chain and guide system. An inspection of this sort of problem should consider replacing the chain driven oil pump and clean the pickup tube which may be clogged with sludge (thick oil deposits) which prevents prompt engine oil pickup.

Hi Paul, I am an ardent reader of your weekly column. Recently a mechanic who was looking at my Toyota RAV4 model 2003 suggested that I should replace the petrol filter. I would like to know how often I am supposed to replace my petrol filter. Jacob.

Jacob, a fuel filter is fitted in both petrol and diesel engine fuel systems and the primary purpose is to trap accumulated deposits or tiny particles that may find their way into the fuel line from your fuel tank. With time the filter gets dirty and clogged with the trapped particles. The restricted fuel filter makes the fuel pump work harder to deliver fuel past the dirty filter. This makes the fuel pump burn out sooner than later. A dirty overdue fuel filter’s pressure regulator will allow debris or deposits to flow through back into the fuel return system where excess fuel pumped but not combusted will be returned to the tank. When the fuel filter fails to strain this fuel as it flows to and fro it will allow the dirt particles to move around and block or damage delicate fuel system components such as the fuel pump and fuel injectors. Vehicle manufacturers usually recommend replacement of fuel filters at particular intervals. Older diesel engines have their fuel filters replaced after every service while newer diesel engines have long life fuel filters which are replaced after 60,000 kilometres or 3 years whichever comes first. On Toyota vehicles with petrol engines, like yours, the manufacturer recommends a first fuel filter replacement at 100,000 kilometres. Subsequent replacements can be after 60,000 kilometres. It is therefore important that you use a genuine replacement part filter from a recognised parts dealer for your Toyota.

Hi Paul, I recently bought a Nissan Lafesta, model 2005. I have enjoyed driving it for about three months. But of late, I hear noise coming from the driving bushes, an indication that they are worn out.
I have tried to ask mechanics regarding outlets from which I can buy shock absorbers and arm bushes, and non seem to know. Could you be having an idea where such can be bought from around Kampala?
Regards
Dr Kule

Dear Dr Kule, Nissan has an authorised dealer in Uganda - Motorcare Uganda. They are situated along Jinja road near Lugogo and opposite Jinja road Police station. They will use your car details to check their parts catalogue and advise if they stock it’s parts. In the event that they don’t have stock, you can discuss with them the option of placing a special order. This will work out fine provided your mechanics have furnished you with a comprehensive inspection or defect report to avoid repeat visits to the Nissan parts shop.

Hi Paul, I am a regular reader of your Ask the Mechanic column in the Daily Monitor of Thursday. My car, a Toyota Premio 2000, has had a persistent wheel wobble at low speeds. My mechanics have changed my tyre rod ends and I have carried out wheel alignment and wheel balancing. The problem persists. What can I do now?

Hello, wheel wobble at slow speeds is usually caused by the condition of the wheels or tyres or components that directly affect wheel rotation such as suspension bushings or hub bearings. In your case, you should request your mechanics to check the condition of the front suspension plates or lateral arms for damaged bushes which cause a play to the attached wheel hub assembly and subsequently a wobble. The car should be hoisted up to inspect the wheel hubs for excessive play suggestive of wear. Worn out wheel hubs can cause a wobble. I am under the assumption that during your recent wheel alignment and balancing the tyre technicians inspected the condition of your tyre treads to rule out uneven wear. This condition can cause a wheel wobble. You need to visit a modern tyre shop and request for a test using a Road Force Balancer machine. This test spins the wheels against a flat surface simulating normal road driving conditions. In so doing the machine will help to determine if the tyres, wheels or suspension of your car are in a condition that is causing your wheel wobble.

Ask the mechanic
By Paul Kaganzi
0772316145
send sms: mycar (space) your comments and questions to 6933, or email them to [email protected]