Comment by LeifCarrotson
18 hours ago
Auto start/stop isn't off for enough time for the oil to drain from the galleries and especially not out of the bearing journals.
It's the first few seconds after an engine has been off for hours (or worse, for potentially years) that are the problem.
I thought it pretty well established that auto on/off is bad for the engine, as is intermittently turning off some cylinders as some do. Is that wrong?
I don’t think it’s pretty well established, there are cars that will happily stop and start the engine multiple times per minute, e.g. Toyota hybrids with their “HSD” drivetrain. It just requires some engineering.
I don’t think Toyota engine does traction from low rpm. Electric motor does it, and moments later already well spinning engine gets the load.
Hearing regular start-stop on intersection gives me sorry feeling for the engine.
2 replies →
“While aggressive start cycles (>20 cycles per day) could lead to premature failure in the starter system of light- to medium-duty commercial fleet vehicles, modern fuel injection and engine control systems have eliminated any issues associated with drivers of typical light-duty vehicles turning the engine off while stationary for short periods and restarting the vehicles for <10 start events per day.” from https://publications.anl.gov/anlpubs/2015/05/115925.pdf
This paper seems to say that generally they aren’t a problem. I’ve only seen unsubstantiated claims that they are one.
This paper reads like a high school science fair project with zero treatment for the concern originally presented (oil system pressure transients).
It sounds like you're talking more about systems that supposedly disengage some cylinders while the car is cruising. Some engines with that kind of technology have been known to damage cylinders for multitude of reasons.
That's very different from the start/stop feature they're talking about. That's about fully stopping the engine when you come to a complete stop like at a red light and then automatically starting again when you get off the brake.