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Wednesday, April 29, 2009

Chain VS Belt

What are the advantages and disadvantages of chain and belt drive trains is terms of durability and maintenances costs? Also, the recirculating ball and nut verses rack and pinion.

Lastly, the common rail direct fuel injection versus the electrical fuel injection turbo diesel. What are their advantages in term of performance and cost of maintenance plus fuel economy?

You cannot expect a detailed reply to such technical questions and so I will only give you a brief reply to eaach:

1. To my mind, the chain drive is better than a belt drive for the camshafts. Also chains do not snap without warning and last for almost forever. However the chain is noisy and it is more complicated to keep it in good tension.

Belts on the other hand are much quieter but must be replaced at regular intervals or else you could end up with very bent valves and even a scrap engine. Belts are not cheap and usually replacing the belt also entails replacing the idlers and their bearings which can come up to quite a hefty sum.

2. The recirculating ball steering tends to be quieter and does not require as frequent adjustment as the rack and pinion. Rack and pinion steerings have very limited adjusments and once that is taken up, the rack can make all sorts of noises. Rack and pinion power steering units also have a higher tendency for leakage.

3. I think you are talking about a common rail system as opposed to a unit injector system.
I would prefer the common rail system for its efficiency and fuel consumption, although the operating pressures are much higher and there is a need to ensure that fuel used is clean.

Transmission Problem

I have a 1997 Volvo 850 T5 experiencing auto transmission problems. Lately, after draining the ATF to facilitate rep;ecement of the drive shaft, I had the transmission filled with Volvo original ATF Dextron III.

Now the reverse gear won't work at all. Other gears are working fine though. I have double checked the ATF level with the engine running and it shows sufficient fluid level at the current temperature. There is no sign of oil leak.

It appears that you did not touch the transmission at set to refill it. I think the problem may be just a stuck valve and would mean taking down the valve block and cleaning it out. It may be just dirt that has jammed a valve. I suggest hat you get someone familiar with A/Ts to have a look at it.

Oil Change

I am using Petronas Semi-Synthetic(5W-30) for my 2004 Kelisa (M). Is it ok to change the oil after 10,000km?

10,000 km is ok for the oil change but is your consuming oil. If so, it may be better to change to a more viscous mineral oil and replace it every 5,000km.

Pulley Change

I am interested in replacing my Kelisa's three-belt pulleys with the after market alloy type. I understand that it will be much lighter on acceleration compared with using the original metal type. Is it a good a idea to change?

The alloy pulleys will definitely look better but your car is not going to go any faster! I cannot see how weight you can gain by the replacement of these parts but of course, the people selling it to you will show you documents to say that this is so.

Faulty Bearing

Sound are heard when I engage the 1st and reverse gearof my Toyota KE70.

If the sound is heard when you engage the gear and the release the clutch, then it is likely that you have a worn bearing in the gearbox. The replacement of bearings in the gearbox is a reasonably straightforward job and can be done by any decent mechanic.

If it is a worn prop-shaft bearing, the noise will be there in all gears.