Whats rustling your jimmies?

Deathwing_sl said:

If it's cold enough that you have to scrape off your windshield, shouldn't you let your engine idle for that long anyway before driving? Honest question, I've been told driving off immediately in cold conditions can cause cracks.

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I don't think that causes cracking, unless it's something that happens in super cold climates. The only cracking I've heard about is if you don't let it cool down properly. Like, if you get it really hot and start hosing it off. In that case I think you'll crack the engine mountings first, as they are usually the weakest link. If you drive a diesel, you can also crack your turbocharger if you don't let the hot engine idle for a while before shutting it off.

The danger in not letting your engine heat up is a little different. Cold oil is thicker and more viscous than hot oil. This means it can't flow properly through all the tiny channels in the block. So, the cylinders are sitting there running without lubrication. I guess that could eventually cause cracking, but whatever it does, it won't be instant. It basically will wind up wearing it out too fast. You need to wait till the engine temp gets into it's normal operating range before you work it. But, there's no reason you have to do that at idle in your driveway. As long as you don't go straight from your driveway to an interstate, you're fine if you just drive it gently until the temperature gets up there. If a mechanic is trying to get your engine heated up, he will run it at 2000 RPM till it gets there. So what's the difference if you're sitting there in neutral at 2000 RPM, or if you're in gear driving down the road keeping it at 2000 RPM or less? Maybe having it in gear will be harder on the transmission, but tranny fluid is thinner and, as far as I know, trannies don't have all the tiny oil holes engine blocks do. Plus, if you're sitting there idling, I don't think you're doing much to heat up the tranny fluid anyway.

I don't know what people were telling khane when he heard to let it idle till it gets to 1500 RPM. That doesn't make any sense, all of my cars idle around 1000. Maybe they were trying to tell him to rev the engine up to 1500.

If you don't have a tach, you have to play it by ear (literally) on how fast you go. Based on my cars, I'd say accelerate like grandma and keep it under 45 until overdrive kicks in, then go up to 55. If you don't have a temperature gauge, I'm not sure what to tell you. But I think all cars have a temp gauge, don't they?

And this doesn't apply to only cold weather. Even if it's 100 degrees outside, you gotta make sure the engine is in it's normal operating range before you open it up.

People at work who don't know how to work an air conditioner. Fuckers get cold and just turn it off instead of turning it up a degree or two. What makes it worse is that most of us are fucking controls engineers. If you can't figure out how to close the loop on an AC system, what's that say about the rest of your work? The only slack I can cut them is that there are a lot of foreigners here, so whoever is doing it was probably raised without AC in their house. But it's still something you should be able to figure out if you're a controls engineer.