Quote:
Originally Posted by CaberTosser
Of course there is an oil film there and their clearances as well as their higher compression are also part of the reason that diesels run higher viscosity lubricant in the first place. I was just noting your incorrect description, when it comes to technical descriptions I'm a stickler for accuracy, heck even the rings have an oil film separating them from the cylinder wall if you want to go down that road. If you want to idle excessively you go right ahead, it seems probable that you're running employer supplied/reimbursed fuel if you're fine with the financial waste of idling for so long. People who pay for their own fuel tend to not be so devil-may-care with how much of it is being burned unnecessarily. Just don't think that everyone else is as easy to blind with inaccuracy as your neighbor is. Until the piston has stabilized its temp and has come to temp the size of that piston is also out of spec.
What is up with the group of fellows who can't bear a brief chill while their vehicle is getting up to temp? I'll drive as soon as I can safely see through the windshield....
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He may have his description wrong but I know what he was trying to explain. When your cold piston (cylinder shape, now shrunk significantly from the cylinder it now rides in) begins to warm from combustion the mass of aluminum varies throughout the piston, thus the piston expands at different rates. Also the bottom of the piston has ambient air temperature oil being sprayed onto the bottom of the head cooling it more than say the skirt. This causes the piston to be shaped more like a trapezoid. So for basic explanations it is a triangle moving in a cylinder. During this time with excessive pressure from compression it forces the thrust side of the piston to tilt causing contact of the cylinder wall as the piston is now travelling cocked in the bore. Then when it goes to intake the piston is flopped in the opposite side of the cylinder wall causing it to contact the opposite side as the cocked piston travels down. This leaves 4 distinct lines on your cylinder wall as someone else pointed out.
I wouldn't argue about a hot water heater with you. I would and have taken any advice you have given about them. I know more about the workings of diesel engines than likely 99.5% of members on this board, please extend me the same professional courtesy. Engines have come a long way in even the last 20 years. A lot of issues we saw as common problems then, now don't seem as prominent. Even Teflon coating pistons helps with cold start-up and the prevention of skirt collapsing. The technology makes the engines more resilient to cold start-up but there are definite benefits to warming an engine up. When you score your cylinder walls as mentioned above, which I see in a lot engines nowadays, I guarantee it causes slight oil consumption, and slight power loss. When this engine needs an overhaul, those cylinders will need to be changed not just honed. (wet sleeve engine) Likely the tech may be uncomfortable with reusing your pistons too. All because you couldn't wait an additional 8 minutes at the cost of 67 cents of diesel.
My personal vehicles all idle to temp, all on my dime. Actually, every internal combustion engine I own (which is a lot when you step back and think about it) idles for a period of time before being loaded. Even in the summer.
As another poster said, "why does google only bring up articles saying not to idle more than 5 minutes." The answer is the same scenario as this thread. All kinds of driver instructors, yoga teachers, and NDP mla's all write their opinions and overwhelm the 3 people that actually professionally work on engines. So the few correct answers are drowned out by the many articles from the dog groomers posting info about diesel engines.