I have heard for years that something like 90% of wear and tear on an engine occurs at start-up. This is due in part to the fact that the first start up of the day is usually occurring when the oil is cold, and has had all night to drip back into the pan, rather than coating the engine parts is is supposed to protect. Racing engines have been equipped for mant years with a "pre oiler", shich is an electric pump that establishes oil pressure and coats the engine's moving parts with oil before the engine is even started. My question is this: with the Prius' internal combustion engine shutting down and re-starting all the time, (can be many, many times during a stop and go trip around town), does the engine get extra wear and tear every time it starts up? I am sure subsequent start-ups are less damaging than the initial one, due to the fact that the engine parts are coated with oil already, but it seems to me that the problem could be eliminated entirely if the oil pump were run by electricity all the time that the POWER is on. Could it be that the Prius also has a pre-oiler? Could this be the faint but audible tinny whine I hear when I push POWER, but before the ICE kicks in? It is said that cars fitted with a pre-oiler can last 2-3 times longer than a traditional engine without one. Allan out
the story is that the engine spins and then applies spark and then fuel to start it. So it essentially starts truning without load on the rods and mains from the combustion in the cylinders. So it should have some oil in the bearings before it actually starts running. On the other hand a cold start is still a cold start.
The whine you hear is the hot engine coolant from the thermos being pumped back into the engine to warm the thingamabobs. This reduces pollution for cold starts. The wear and tear of starts on the engine is insignificant, due to the Prius's unique method of starting. Other cars wash the cylinder walls with gasoline while the engine is cranking. The Prius spins the engine up to 1,000 rpm before injecting gas. This helps protect the engine, and reduces pollution at the same time.
Okay, so I'm not quite sure what it is that gets heated by that stored hot coolant, but I know that it happens, and why it does. Cylinder heads and valves come to mind, but I don't really know what cylinder heads are, or why warming the valves would make a difference. I'm more interested in theory than in details.
it is the sleeve that surrounds the intake manifold. also because the engine is spinning at 1000 RPM's before gas is injected means the oil pump is pumping oil BEFORE the engine starts up. in an ICE, the engine is cranked by the starter at 100-150 rpms and dumping gas into the cylinder. unburned gas will dilute the oil on the cylinder walls destroying its lubricating properties. this is wear the excessive wear happens. for a great demostration of this idea. check the oil in youir Prius. I have 3500 miles on my Prius and i still have problems determining the oil level because the stuff is still amber colored and clear and difficult to see on the dip stick. i usually have to do 3 dips to make sure im seeing what i think i see. and this is better than 40% city driving (estimated) i only have a 10 mile commute to work with 7 miles freeway, so my freeway driving has been trips. (i do make more than i used to)
This has been described in better details elsewhere on the board (and apologies, I couldn't find the article about this): Actually, the engine in the Prius gets, overall, less wear and tear than most engines: because the greatest amount of strain on an engine is when it's being run "throttled down", at lower speeds. One of the HSD's primary missions in life is to only run the ICE at its optimum speed, as much as possible. I want to keep my new car for some time; that's one of the (many) things that appealed to me about the '04 Prius.
It's also the intake ports and then the head itself, but I believe it does pass through the sleeve first. The whole point of the design is to reduce or eliminate the condensation of gasoline on the intake ports during cold starts. Now if we could only have the HC absorbing cat to boot, we'd be really clean. I do notice that our cold start exhaust is a bit "smellier" (higher HC content most likely) before the cats light off - I didn't notice this on my '02 which has the HC absorbing catylitic converter instead of the thermos.
condesation of gas is one thing, also moisture control is the other. water in the air inhibits thermal expansion which in turn lowers overall horsepower ratings. heated air has lower moisture content and therefore heats up faster and hotter during the combustion stage. by heating the intake manifold, it acts as a dehumidifier. also keep in mind that "metal fatigue" ( the expansion and contraction of metal as it heats up and cools down) is greatly reduced thus increasing the life of your engine. also heating the air up to something like 35ºC will give you about a 10% increase in horsepower ( the numbers are from one of my bad memory days, so use for argumentative purposes only please)
