Fluid Film on Startup?

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2,569
Location
College Dorm...
This is from a post by carl97ss: "The car had not run for 39 hours and it was 20 degrees F on Sunday morning. At cold start up, my car idles at 1050 rpm's. It took 38 seconds for oil to appear at the top of the pushrod were it meets the roller rocker. It took another 20 seconds (58 secs. after start up)for oil to work it's way to the tip of the roller rocker where it meets the valve stem. At the same time, 58 seconds after start up, oil appeared at the base of the valve spring where it sits on the cylinder head. By this time, the engine's idle had dropped to 900 rpm's. Oil started to appear on all the pushrods. rockers/springs within +- 3 to 5 seconds of each other. I suspect with a factory oil pump things might take a bit longer...." Now if this is true, how is an engine so quiet on startup? As far as I know, the loud tick-tick-tick noise some get on startup is because of a hydrodynamic film not being present. So my question is this...if a fluid film is not present for such a long time, how can an engine be so quiet on startup, with no noises but the smooth purr of the engine itself?
 

KW

Messages
1,686
Location
Central Arkansas
As long as the lifters are pumped up the motor will be fairly quiet. There is enough resiual oil on everything else to be ok until oil gets to it. Just spill some Kendall ot M1 on your motor and try to wipe it off. It just clings there for life.
 
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2,480
This post debunks the other thread re: wear at startup... I too think it's over-exaggerated...ie. unless you redline the engine 5 seconds after starting it, there is a film thickness on all the parts regardless of temperature completely adequate until a point in time in which new oil can reach all areas. This is why it is important to drive slowly while the engine is warming up...
 
Messages
1,565
Location
palm beach
if i start up my car and get out and open the oil fill cap, the cams (dohc) are flinging oil everywhere on top of the cylinder head in only the short time it takes for me to get out of the car and open the oil cap. this oil which is flung everywhere, also makes it to the valves, which are right under the hla. basically, oil has to travel 1 inch from the cams to the valves, which are splash lubed by the mess the cam makes. i would venture to say my valve tips get oil in about 10 seconds. if his engine takes nearly a minute to have oil reach the valves, that is quite incredible really. one has to wonder why pushrod engines dont wear out sooner.
 

MolaKule

Staff member
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21,951
Location
Iowegia - USA
You don't have to have a puddle of (bulk) oil to have a residual layer of oil film that had been pumped there before the last shutdown.
 

TC

Messages
1,644
Location
California
From the Shell Canada website: "Is it harmful to rev my car's engine when I start it? Yes. The startup period is the time when the engine experiences the most wear. By accelerating it before the oil reaches the top of the engine cylinders -- five or more seconds depending on the vehicle -- you can do a considerable amount of damage and speed up engine wear." http://www.shell.ca/code/motoring/tips/engines.html
 
Messages
622
Location
42.4N 85.7W
Just from the great service life we get out of our Subarus, I have to agree w/ Mola. In the flat design the oil CAN'T puddle on the followers or anywhere for that matter since the heads are vertical. If Porsche and Subaru can make it work (and work that well for that long) then this is ONE item I won't lose sleep over. Ok, I'm an oil nut, so I will but it's way down there on the list! [Cheers!] Dave
 
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