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Old 17th December 2012, 14:13   #106
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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Originally Posted by SS-Traveller View Post
A cold start on a winter morning in Delhi would invariably see an ECM-controlled petrol engine rev up to around 1600-1800rpm for the initial few seconds, before it settles down to 1200-1300 rpm.

Letting the engine idle for 30-60 seconds after initial start, before engaging gear and driving off, allows the engine oil to circulate properly.
Spot-on SS-Traveller. All modern car engines are controlled by ECM and they will be in high-revs at start-up. Even in non-ECM controlled engines, the auto-choke carburetor would keep the revs high. For non-auto-choke carburetors we had the manual choke.
But till now i used to be of the opinion that cold engines should be kept on idle for 45-50 seconds before moving till recently i read somewhere that keeping the engine running cold will do more harm then good. Reason being that the engine operates best & remains healthy when it runs hot. It is better to take the engine to running temperature as soon as possible (not to exceed 2000rpm) and not keep it idling at cold temperature. And that's the reason why ECM raises the rpm - to bring it to operating temp ASAP.
For the oil not circulating theory - it was true for old engines & old grade oils. Modern engines have a very good oil circulation and oil companies have done enough R&D to prevent damages due to cold-start.

Last edited by KkVaidya : 17th December 2012 at 14:15.
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Old 18th December 2012, 15:14   #107
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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As a rule of thumb, it is best not to switch off a cold engine
How about driving a turbocharged diesel in it's idle rpm(750-900 rpm) immediately after starting(without using accelerator)? Will it cause any long term harm to the turbo and other engine parts?

My parking slot is at the end of the building and i can move slowly in idling rpm till i reach the gate, it takes a good 15 seconds for that. Hence the query!

Thanks.

Last edited by ramzsys : 18th December 2012 at 15:23.
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Old 18th December 2012, 18:43   #108
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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How about driving a turbocharged diesel in it's idle rpm(750-900 rpm) immediately after starting(without using accelerator)? Will it cause any long term harm to the turbo and other engine parts?

My parking slot is at the end of the building and i can move slowly in idling rpm till i reach the gate, it takes a good 15 seconds for that. Hence the query!
Don't foresee any issues - unless you switch off again after 15 seconds!
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Old 21st December 2012, 14:44   #109
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

One quick question, and I am very sorry if this has already been covered in the past. I wanted to know what your views are on braking using the engine. I used to do that quite often when turning or when coming downhill with my old car (Swift Petrol), but am not very sure if thats a good thing.

And with the diesel engine I am more so no sure if its something that can cause damage to the engine ?
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Old 21st December 2012, 17:40   #110
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

Make sure that you rev match the engine and gear speed while you downshift.
I don't think it should cause any damage then.
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Old 21st January 2013, 15:15   #111
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

I have a question regarding leafspring in car. Do they break without giving any warning sign? Last day the rear leafspring on my Maruti 800 just broke without any warning with a loud metal breaking sound. There were squeak coming from rear suspension few days before but thats is? Do leafspring just make squeking sounds before dying? And lastly is it safe to take car with a broken leafspring to service center situated at distance of 7 km?
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Old 21st January 2013, 22:48   #112
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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I have a question regarding leafspring in car. Do they break without giving any warning sign? Last day the rear leafspring on my Maruti 800 just broke without any warning with a loud metal breaking sound. There were squeak coming from rear suspension few days before but thats is? Do leafspring just make squeking sounds before dying? And lastly is it safe to take car with a broken leafspring to service center situated at distance of 7 km?
I've had both rear leafs on my M-800 break within a few days of each other in 2000, after a gruelling 1800-km trip to Garhwal. No warning, no squeaks. Both springs broke from the rear end, and the tyre did not contact the mudguard and was free to rotate. Both times I drove it to the garage (FNG) about 12 km away, driving solo and slowly, to have the particular leaf replaced.

The replaced springs were of the local variety and had less temper, so the car lost ride height after a few months - the springs had to have a 'helper' leaf inserted to restore ride height after that, but did not collapse or break again till I sold the car in end-2001. There was no difference in ride comfort.

Hope that helps.
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Old 8th April 2013, 02:13   #113
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

What are the effects of the following on clutch life?

1) Engine braking.
2) Lugging the engine, in particular, at slow speed city drives.
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Old 8th April 2013, 10:52   #114
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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What are the effects of the following on clutch life?

1) Engine braking.
2) Lugging the engine, in particular, at slow speed city drives.
If you've got your foot off the clutch pedal completely, either of the activities has absolutely no effect on clutch life. A fully engaged clutch in good condition will not slip, and a clutch which does not slip does not wear out.

However, lugging the engine in high gear at slow speeds will of course be detrimental to the life of the engine in the long run. Again, engine braking does not affect the engine UNLESS you allow it to reach very high revs / exceed the redline while being driven passively by the wheels.

Last edited by Eddy : 19th May 2013 at 14:29.
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Old 17th March 2014, 20:56   #115
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Default Re: Mechanical Empathy | Clutch

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Clutches burn/wear out because they slip. And they slip because your left foot makes them. There's no way that I can prove how well or badly you drive, except by assessing how long your clutch lasts before suffering terminal slippage. Cars that I have owned and driven personally, usually had clutch service life of over 100,000 km. Similar clutch life has been reported by others on the forum, and off it.

Keep that left foot off the pedal as far as possible. A lower gear than what you are crawling along on, and a slightly higher rpm, will allow you to remove that left foot from the C-pedal completely, without making the car shudder. When crawling in traffic, get the car to roll a little, then shift back to neutral and let go of the clutch. Wheelspin on standing start impresses your friends, but murders the clutch as well as the driveshafts / propshaft / tyres. If you are stuck in mud and gunning the engine to spin the wheels, forget it after the first time - the car just won't come out unless you use the right technique. And the right technique might just be to call in another vehicle to tow you out.
Does keeping the clutch fully depressed with the car in 1st gear while the car is stationary (for say, about a minute) in bumper to bumper traffic cause any damage to the the clutch?
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Old 18th March 2014, 07:20   #116
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Default Re: Mechanical Empathy | Clutch

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Does keeping the clutch fully depressed with the car in 1st gear while the car is stationary (for say, about a minute) in bumper to bumper traffic cause any damage to the the clutch?
Ideally, no.

However, there is usually some clutch drag, and that wears out the friction plate. One minute doesn't hurt, but when you make it a habit, it does to some extent.

As a quick experiment, jack up one of your driven wheels, then keep the clutch fully depressed with the car in 1st gear. You'll usually find that the wheel rotates. Try stopping the wheel, and you'll realize how much friction is being generated by even a fully disengaged clutch.
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Old 3rd April 2014, 13:53   #117
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

I do not know whether this is the right forum to put my question but off-late i have observed that modern cars having this unique tail pipe design.
Almost all modern petrol engined cars have their tail pipes with a U cut on top and are bent downwards. Is there any specific reason for this?
I have observed the Alto 800, Ertiga, Brio etc with this kind of a design. I am sure there should be a certain reason for this unique design espeically the U cut on top.
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Old 21st May 2014, 18:40   #118
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Default Re: Mechanical Empathy | Engine

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The engine oil is the most crucial factor that keeps an engine healthy.
My mechanic always pulls the drain plug when the engine is hot; by hot i mean normal operating temperatures. He lets the oil drip for about half an hour, and after the engine cools sufficiently he keeps his hands on the oil filter. Until then he attends to the other chores.

This in contrast to what was happening in the Ford Service station i visited yesterday: every car that came in was waiting for 1 to 2 hours before they were raised and the drain plug pulled. There's no warming up of the engine happening.
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Old 21st May 2014, 19:37   #119
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Default Re: Mechanical Empathy | Engine

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My mechanic always pulls the drain plug when the engine is hot;...in contrast to what was happening in the Ford Service station i visited yesterday: every car that came in was waiting for 1 to 2 hours before they were raised and the drain plug pulled.
Warm oil flows faster. But cooled engine oil will still flow out, only a little extra time may be required.

Waiting half an hour for warm engine oil to flow out isn't necessary.

Also, a warm engine switched off and the oil drained immediately prevents the dissolved solids from precipitating out of the oil into the pan - ideally that's a good thing, but if your oil changes are on/before time, and the wait period before draining is short (1-2 hours), it doesn't matter.

I wouldn't do an oil change on an engine that has been sitting around without being started for two weeks.
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Old 21st May 2014, 19:39   #120
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

What's the best was to move an old car (say amby or fiat or pp) up an incline after coming to a dead stop without rolling backwards ?
Note- Either there is no hand brake or it is removed
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