If I've missed a discussion that speaks of wear element sources induced from cold start situations, sorry for the topic duplication.
During a walk today I pondered just what areas would mostly be impacted during cold start/warm-up. I pondered plain bearings (mains and connecting rod), be them lead overlay or aluminum (any bronze?), but aside from the initial traction of the rotating shaft within the circumference of plain bearing riding up and then slipping (grip'n slip), a film would quickly be generated as rotation increased assuming a supply of oil is availible.
As was read in a question-answer section of a lube site, using too thick a viscosity for the temperatures in which unadded/unheated starting would likely occur, a case of bearing siezure was given. It's been a while since i read this, but IIRC the responses pointed to oil refill rates in the bearings being unable to keep-up with the bleed-out rates...ultimately being unable to support the load. For similar reasons I would try to avoid high rpm/high load conditions until fluids are at or shy of full operating temperature. That said, it would seem then that the more common occurrances with bearing wear is rather brief - grip, slip, hydrodynamic film.
Cylinder liner and piston ring wear would be another location of increased wear. Not only is there a likelihood for oil washout from an enriched fuel mixture, the viscous oil now has to keep up with the pistons rate of movement along the walls. Granted, work upon the oil here would lead to thermal thinning and yielding better lubricating results with the prime heat source of combustion so near, but how much? Engines not equiped with piston squirters rely on splash/oil slinging...how well does that work with thick oil?
How much might cam bearings be impacted during cold start conditions? Lobes? The longer the lubricant travel from pump to port, the less desireable for any oil, any temp? There is also the inevitable thermally related part fitment as a constant in any thermal cycling of mechanical equipment for which there is little any of us can do beyond reducing such cycling. Is there truth to what I heard somewhere that diesels suffer more wear during cold start/short trip operations than gasoline counter parts...and if so, what regions might they be?
So, coming to terms with an engine receiving a majority of it's wear during start/warm-up conditions, let's talk about regions, likely localized conditions and constraints, and see if once and for all, one can or cannot find solutions to atleast help minimize such situations. I know an engine is likely to outlive the vehicle it's in, but for the sake of understanding and comprehension, work with me. We're visiting BITOG for pete sake;-).
During a walk today I pondered just what areas would mostly be impacted during cold start/warm-up. I pondered plain bearings (mains and connecting rod), be them lead overlay or aluminum (any bronze?), but aside from the initial traction of the rotating shaft within the circumference of plain bearing riding up and then slipping (grip'n slip), a film would quickly be generated as rotation increased assuming a supply of oil is availible.
As was read in a question-answer section of a lube site, using too thick a viscosity for the temperatures in which unadded/unheated starting would likely occur, a case of bearing siezure was given. It's been a while since i read this, but IIRC the responses pointed to oil refill rates in the bearings being unable to keep-up with the bleed-out rates...ultimately being unable to support the load. For similar reasons I would try to avoid high rpm/high load conditions until fluids are at or shy of full operating temperature. That said, it would seem then that the more common occurrances with bearing wear is rather brief - grip, slip, hydrodynamic film.
Cylinder liner and piston ring wear would be another location of increased wear. Not only is there a likelihood for oil washout from an enriched fuel mixture, the viscous oil now has to keep up with the pistons rate of movement along the walls. Granted, work upon the oil here would lead to thermal thinning and yielding better lubricating results with the prime heat source of combustion so near, but how much? Engines not equiped with piston squirters rely on splash/oil slinging...how well does that work with thick oil?
How much might cam bearings be impacted during cold start conditions? Lobes? The longer the lubricant travel from pump to port, the less desireable for any oil, any temp? There is also the inevitable thermally related part fitment as a constant in any thermal cycling of mechanical equipment for which there is little any of us can do beyond reducing such cycling. Is there truth to what I heard somewhere that diesels suffer more wear during cold start/short trip operations than gasoline counter parts...and if so, what regions might they be?
So, coming to terms with an engine receiving a majority of it's wear during start/warm-up conditions, let's talk about regions, likely localized conditions and constraints, and see if once and for all, one can or cannot find solutions to atleast help minimize such situations. I know an engine is likely to outlive the vehicle it's in, but for the sake of understanding and comprehension, work with me. We're visiting BITOG for pete sake;-).
