Quote:
Originally Posted by ramzsys http://www.team-bhp.com/forum/techni...57000-kms.html
With respect to the above thread, (apart from manufacturing defects), what causes a premature timing belt/chain failure?
Every manufacturer will do the long term tests and suggest replacement intervals based on that; but what causes/inputs from the user end causes a timing belt/chain to fail prematurely?
From my basic understanding, i suggest that waiting for the engine parts to warm up- (this includes the belts and chains) and avoiding unduly harsh acceleration can help. |
On the timing belt/ chain failure: nothing really. Its unusual for it to fail unless there is some defect. Certain engines have been known to have certain problem with for instance tensioners. But otherwise there is very little that goes wrong and if you stick to the manufacturer recommendations you would be fine. Other than manufacturing defects I would say a concern could be how to actually replace them. It does take some knowledge and depending on the engine, some specials tools to replace the chain/belt. Although I don't have data as such, I would think more problems occur after chain/belt replacements as part of normal preventive maintenance then when an engine coming fresh out of the factory. Wont happen immediately, but if not installed correctly with the proper tools, proper tensioning etc, it is a disaster waiting to happen.
There is a huge misunderstanding on this forum what causes wear and tear on an engine. RPM and loading isn't really one of those. It will affect FE but not much else. As a rule of thumb city driving versus highway driving is a much more important factor. The number of cold starts or relatively short drives as well. You drive your car twice a day in the city on the commuter run for thirty minutes, in heavy dense traffic will put a lot more wear and tear on it then the guy who does four hours per day on the highways, running at 2500-3500rpm for hours on end.
Car engines are designed to work across the whole range of rpm and loading. Low revs are often a problem for piston ring cylinder lubrication. Keeping engines revs up tends to be better on engines for lubrication, heat dissipation and stress on the engine and drive train, but of course it tend to comes at the expense of FE. Most engines, diesel as well as petrol, run best from a wear and tear perspective if you run them between 75-100% max loading. That is not typically your best FE, but its best for wear and tear. I wouldn't think much of buying a car that has clocked up 100.000 km in 2/3 years. Because in Europe that means mostly highway miles, high speeds, high rpm. Engine will be barely run in. I have never ever bought a car in my life with less than 100.000 km on the clock (other than my company cars which were always new). But I have had never had any major problems because of wear and tear, or an chain/belt failure.
As long as you don't red line your engine, you will be good. My observation of two years in India is that all drivers seem to be obsessed with low revs. I don't know if that is to get the best FE or what. Even in situations where you really need to accelerate fast I see everybody upshifting very quickly rather then to use the rev band a little bit more liberally.
Ensuring your engine is properly warmed up before giving it the beans is really relevant. Don't look at your cooling water temperature for that. If you have an oil pressure gauge, that is the best indication. Once the oil pressure drops to normal values you will be fine. If you have only an cooling water temperature, wait until it registers normal temperature and add another 5-7 minutes for good measure. It will take that long for the oil and the various engine and transmission components to warm up properly.
Especially modern diesel are hugely efficient, which also means they take a long time to heat up properly. When cold, around or below zero it might take a real long time. Never start your cold engine and leave it idling for minutes to warm it up. This is a particularly bad practice that does cause real wear and tear very quickly, notably on the cylinder liners and piston rings. Its also really bad for the environment if you care for that. Start and drive away immediately but be gentle with the right foot until the engine is properly warmed up through and through.
Jeroen
Jeroen
Jeroen