I agree that the major wear is at cold startup...intuitive
I agree that the major wear is at cold startup...intuitive.
I disagree that this "wear" is excessive in most street applications. It is not at all uncommon to have modern engines make 400,000 miles and still be serviceable. My son and I put over 385,000 on a '77 360 Dodge PU before we sold it and there were no problems in the engine dept.
My auto insurance agent has a MB that is at the 400k mark.
My point, is that this simply means that there is no incentive for OEM to do anything with pre oilers/after oilers/accusumps, etc.
For the uninitiated--- I use the Canton 3 qt. Accusump with an electric pressure (55psi in the Mini, 35psi in the Lotus) regulated solenoid and prior to any cold startup crank the engine over several times before turning on the ignition...simple...and...if the engine has been sitting around over the winter, I take out the plugs and crank it over for a bit before final startup. Again, simple.
I would argue that pre-oiling does not provide as much benefit as one would imagine. However, allowing the engine to idle and cool off before shut down would provide benefit, especially with a turbo engine.
Most of the sliding contacts in a recip piston engine (rings, wrist pins, valvetrain, etc.) are capable of operating safely for short periods with whatever entrained oil is present at start up. Most of these components normally operate with boundary type contacts and thus don't require much oil to be present.
As for the hydrodynamic contacts present in the main and rod bearings, these also do not require much oil flow at start up. The oil volume that must be present to produce the load supporting hydrodynamic film is extremely small (ie. a small drop). The normal operating oil flow required by journal bearings is based entirely on cooling requirements. And for the 2 or 3 seconds of light load, low speed operation at start-up before oil pressure is built up and flows begin, no real damage should be occurring to the bearings since they won't build up much heat.
Bearings are more likely to fail due to surface fatigue, corrosion, or contamination. Not "wear" at start up. Self-priming pumps
2011-07-03
