Crankshaft rotation before engine starts

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Hi Friends,
I just wonder about this. When you start up the car, how long does it take for the oil to reach the piston rings ?
And, is higher number of crankshaft rotations before the engine start is good for cylinder wall lubrication ?
My car has GM, 4 Stroke SOHC engine, and surprisingly, the engine starts almost as soon as you turn the ignition key.
It sounds great, but does it mean that piston rings will starve for oil ? (Since the leftover oil at the cylinder wall from the previous operation will be burnt immediately in combustion chamber)
Regards.
 
200 rpm is the average cranking speed so there isn't a whole lot of oil pressure building up at that rpm so the quicker it starts the better.
The oil left on the cylinder walls, bearings, cam and other internals is enough to keep things lubed until pressurized oil reaches it.
 
The high idle speed the engine momentarily goes to upon startup, in part, serves to get oil pumped/slung to the different areas quickly, but doesn't rev so high as to cause more harm than good before fresh oil gets there. An engine can build a little bit of oil pressure at cranking speed if cranked long enough, but that's hard on the starter and seems like a non-issue given the longevity of engines already.
 
Dry starts are one of the duties of boundary lubrication-the ZDDP, titanium, or other deposits are left behind, along with some oil, to lubricate until the oil pump can deliver enough oil to everything. That's why I let the engine idle, no additional throttle, for 5-10 seconds (longer in cold weather with thicker diesel oil) before putting in gear and being easy on it until the temperature gauge hits the normal range.
 
There are some videos in this forum showing how long it takes oil to reach the rocker arms and cam bearings. Anyone recall where they are? I think the general conclusion was don’t lose sleep over it, the residual oil takes care of things until the pressurized oil reaches the components.
 
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Sis' old (1988) Jeep would crank through 2 full engine revs because two positioning sensors needed to go through their zeros (i read).

I always thought that was not a bad thing because it started oil on its way at the very least.

Never have I seen data one way or the other.
 
On my 1988 Escort, with 15W-40 HDEO at a temperature of about +15C ( 60F )it takes about 4 seconds for oil to appear at the top of the engine when started from cold.
I normally start it up, then let it run for 10-15 secs before getting going when started from cold ( Mechanical injection so runs a little rough the first few moments of running )
 
Thanks for detailed answers.

Originally Posted By: Snagglefoot
There are some videos in this forum showing how long it takes oil to reach the rocker arms and cam bearings. Anyone recall where they are? I think the general conclusion was don’t lose sleep over it, the residual oil takes care of things until the pressurized oil reaches the components.


Well, that is correct. But since my question is more about cylinder wall lubrication, wouldn't residual oil burnt there just after the first combustion process ?
 
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Originally Posted By: Snagglefoot
There are some videos in this forum showing how long it takes oil to reach the rocker arms and cam bearings. Anyone recall where they are? I think the general conclusion was don’t lose sleep over it, the residual oil takes care of things until the pressurized oil reaches the components.

+1
 
Originally Posted By: NICAT
Thanks for detailed answers.


Well, that is correct. But since my question is more about cylinder wall lubrication, wouldn't residual oil burnt there just after the first combustion process ?


Not sure about the last part of the sentence, but there should be some residual oil films in between the rings.

I would say sometime during the first complete rev you're going to have oil sling up to the cylinder wall and underside of the piston crown. Not to mention that Boundary Lubrication is acting due to the additive package.

I wouldn't lose sleep over it.
 
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Originally Posted By: NICAT
Thanks for detailed answers.

Originally Posted By: Snagglefoot
There are some videos in this forum showing how long it takes oil to reach the rocker arms and cam bearings. Anyone recall where they are? I think the general conclusion was don’t lose sleep over it, the residual oil takes care of things until the pressurized oil reaches the components.


Well, that is correct. But since my question is more about cylinder wall lubrication, wouldn't residual oil burnt there just after the first combustion process ?
Piston rings actually (if they're not severely worn) scrape the oil off the walls (at least the oil control rings do) and accumulate excess oil between them and the piston, which drains through the slots under the rings back down to the sump. Usually oil is returned by piston oil squirters or being slung off the big end rod bearings on the crank-both of which (IMHO) would be adversely affected by thick, cold, high viscosity oil. That's why I baby an engine until temperature starts to increase & oil is flying all over the crankcase.
 
In my Ford 2.3 and 2.5 engines I removed the oil fill cap where you can see one of the cams. With a light, I had my wife start the engine and oil was immediately flying around the cam. This was the first start of the day. So don't be concerned except if you are using an oil too thick for cold temp starts where flow may be an issue.. Otherwise you are good.
 
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Originally Posted By: Snagglefoot
I think the general conclusion was don’t lose sleep over it, the residual oil takes care of things until the pressurized oil reaches the components.


Correct.... The residual oil stays on for years,

I have disassembled engines that have sat “unrun” for decades,
& there was still plenty of oil on all the internal parts
 
Rings never see pumped oil anyway. It's always sling oil off the crank. They can live on residual oil film for many minutes before they start to have issues.

The oil is not all burnt off. Burning requires that a substance reaches combustion temp. The water cooled cylinder walls prevent the oil film from completely flashing off. There is always a molecule or two thick oil film on even the upper walls exposed to combustion gasses
smile.gif
 
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