Ask the mechanic: Egrand vs Alphard

I have been reading the quite impressive and detailed ‘Ask The Mechanic’ and together with my friends, have been having arguments about cars; the particular ones being the Toyota Alphard MNH15W and Nissan Elgrand NE51. Both of these vehicles are four wheel drive vans with 2500cc engines and manufactured in 2003. In terms of strength, comfort, durability and fuel consumption, which one would you recommend? I know Toyotas have a better resale value than Nissans but without looking at the sales point, which of these two cars is better?
Nalima in Kampala

You and your friends ought to acknowledge that the second generation Toyota Alphard and Nissan Elgrand (2002-2008) luxury multi-purpose vans (MPV) were designed and knitted with the best passenger luxury trappings and comfort features available at the time. Toyota and Nissan pulled almost all the stops. The exterior front styling was aggressive and futuristic and built strong in keeping with the Toyota and Nissan tradition of reliability as well as durability.

The interior comfort features offered in both MPVs range also offer high quality leather upholstery and reclining seats with automatic retractable foot rests such as those in an airline business class. Full audio surround entertainment and automatic climate control. The Elgrand has an edge over Alphard in the design outlay and kitting of comfort amenities.

Elgrand’s chairs can swivel to different angles to give the passengers a better view. Elgrand offers a convenient electric side door as well as entertainment with multiple overhead television monitors. In performance terms Elgrands’ VQ25DE 2.5 litre (2,495cc) engine is more efficient (powerful and economical) than Alphards’ smaller VVTi 2.4 litre (2,400cc). Elgrand’s engine delivers 140 kilowatts of engine power while Alphard delivers 118 kilowatts.
This gives the Elgrand ample engine power to carry the minivan uphill while loaded with all luxury electric consumers switched on, with more ease than the smaller engine in the Alphard. Despite having a bigger and more powerful engine, the Elgrand delivers the same fuel economy (11.2 Kilometres per litre) as the Alphard. The Elgrand offers more value for money.

My Toyota Premio has been continuously overheating and lately it is puzzling. We have checked the radiator and cooling fans and both seem to work fine. We have also checked the water pump which the mechanic says is okay. What could be the problem?
Taremwa.

You need a good mechanic to check your engine thermostat. This is a heat sensitive valve located in a housing where the upper radiator hose attaches to the engine. Its role is to regulate engine temperature by allowing cool water (coolant) to flow into the engine from the radiator and restore normal engine operating temperature (80 degrees centigrade). A bad thermostat can cause an engine to overheat if it gets stuck in the closed position and prevents coolant fluid from flowing into the engine when it gets hot.
Symptoms of a bad thermostat include almost immediate temperature spike (over heating) as displayed on the temperature gauge as you drive off; leaking thermostat housing and turgidity of the upper radiator hose pipe, suggestive of the fact that coolant is not flowing past the thermostat, when you run the engine. Often motorists are tempted to throw away the thermostat which avoid replacing it with a genuine part, this can be detrimental to engine performance.
An engine without a thermostat will be over cooled and this will cause poor performance and poor fuel economy. The post 1990s electronic fuel injection engine’s fuel and spark delivery by the computer relies on engine temperature information. Eliminating the thermostat will allow cool water to flow constantly into the engine hence keeping the temperature constantly low. Due to the deliberate engine over cooling the computer will assume its a cold start keeping the idling revs up by delivering a rich mixture of fuel . This is not only wasteful but leads to poor engine performance.

I drive a VW Touareg 3.0 litre petrol. Lately, I smell petrol when I accelerate and the check engine light comes on. This started after my mechanic checked the fuel pump when I was starting in the morning. He couldn’t find the cause of the petrol smell and the check engine light after combing the engine bay. What could be the problem or where should we look?
Mark.

This smell of fuel must be the result of a fuel leak. This fuel leak is most likely under the rear right passenger seat, above the fuel tank cover which houses the fuel pump and fuel pressure regulator. There is a rubber seal under this fuel tank cover which could have accidentally been damaged when the technicians were inspecting the fuel pump which is located in this part of the fuel tank. This fuel probably leaks near the hot exhaust pipe so you must attend to it soon.

The seal is not expensive but the replacement is tideous as it involves putting down the fuel tank after dismantling the propeller shaft and rear suspension. You need good technicians to do this. The check engine light is probably a fault code generated by the fuel pressure regulator after detecting the fuel loss due to the leakage. That will be sorted out once the leak is stopped.

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