The handbook for my K11 Nissan Micra recommends letting the car idle for at least 30 secs after start up, presumably to let the car warm up.
Surely some mistake? Isn't the best policy to drive off straight after starting -- the engine will warm up quicker that way, anyway.
Or does the engine management system need 30 secs of readings to get its bearings?
Mike
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I always let my car idle for a few seconds on start up. Reverse out the garage on tick over (its an auto) get out and leave engine running to shut garage door.
I certainly don't feel like a sprint straight after getting out of bed, I asume my car doesn't either!!
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I read somehere that you should allow most cars about 15 seconds idle if you're foing a short run, something about giving the oil pump a chance to re-circulate the oil or something, apparently this saves a lot of wear. I'll try and remember where I saw it...
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I can hear the fuel pump at the back of the car start up as I switch to "On".
The oil warning light goes out during starting, indicating that oil pressure has built up in the engine. This takes about 2 secs.
Mike
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The oil pressure may be fine but it doesn't mean that it has circulated around all the eninge. I don't really know, I'm just going on what I read in a reasonable looking source, certainly allowing it a few seconds to circulate couldn't hurt...
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Was there not some speculation 10 or so years ago about the propensity of some petrol Pug 405's to develop an oil habit while the equivalent BX's did not?. On theory was that the Cit. owners would idle the engine while the hydraulics sorted themselves out, the Pugs were driven straight off before the oil had been circulated round the top of the engine in sufficient quantity.
This is a completely different practice from "warming up", best carried out on the move but avoiding labouring or revving for the first few minutes. .
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Oil pressure warning lights are the most misleading device ever fitted to any car. They are set so low, about 5 psi, that the engine has no oil circulation by the time the light comes on. The pressure switch is the first thing uprated on any competition car, befrore even fitting go-faster stripes!
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I got taken to task by Guy Lacy for admitting this in this very forum, I used to let the Beemer idle before moving off....By the way what happened to the Lacy bros ??
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Your handbook is quite correct. Following this advice can seriously extend the life of your engine. Basically it is to allow the oil a chance to get around the engine and lubricate all those non-pumped areas (eg cam lobes) before it's put under load. Driving straight off after starting causes massive wear in areas such as piston rings, cam lobes and valve stems. It also allows the oil in the gearbox to get going too.
This is not the same as allowing your engine to idle for 5 mins plus to get to full operating temp - definately bad practice. If you do this the excess petrol used when cold washes the oil off the bores and into the sump. This creates excess wear on the bores and dilutes the sump oil causing it to deteriorate quicker which in turn causes excess wear if the oil isn't changed in good time.
Personally I back the car out the garage leaving it running whilst I shut the door (winter only). I then drive off gently for the first few miles, allowing the engine to warm up thoroughly before making full use of the turbo. In the summer months I push the car out the garage, but wait 15 seconds after start up before driving off.
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Its not just when the engine is clock cold.
Some years ago traffic patrol cars (Grandad's with the DOHC engine) had a problem due to sitting up on top of the little observation hills by the M1. If the engine had not been left idling, on getting a shout, the process of firing it up and immediately getting underway caused wear problems with the camshaft and valve gear.
Equally bad is sitting there with the engine idling for ages of course. (Cue for a post from the ranters)
Liked the idea of oil temperature gauges, and wait for a decent reading before giving it some clog, equally it tells you if too much welly means a spell of easier running is needed or an oil cooler upgrade.
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