OK engine experts, I've searched here and on the web and was surprised by how little info I found. There's plenty of info that suggests engine damage can occur from long idle times where diesels are concerned (less oxygen being drawn into the cylinders, thus buildups being drawn into the engine, and all that). My question relates to gasoline engines. Assuming you adjust your oil change interval accordingly, do modern, computer-controlled engines do OK with long idle times or is this just a no-no? If it's a no-no, other than fuel economy and shorter oil life, what specifically is being damaged and at what idle time (ten minutes, an hour, four hours, etc) and over what range of time (a month of doing this once a week, a year of doing it every day, etc).

OK, that was a lot of questions. Any opinions welcome...

Thanks.

 

I'm not an expert, but.........

I've seen lots of Police cars that idle 24/7, and those motors routinely run over 100K, and are sold to private owners, and keep running.


They don't seem to have a problem with it, although they do crack the hood open, slightly.

 

Idling is generally speaking the hardest on an engine, although frequent oil changes would solve many of the problems. I would be concerned about your exhaust, if you have cats. The combination of the rich idle mixture and not enough heat in the exhaust would cause the cats to clog. I know that when it comes to warming up an engine, you don't want to let it idle any longer than it takes for the idle speed to return to normal, but I'm guessing your question isn't about warming up the engine.

 

Thanks all. I've been idling my engine to warm up the interior due to some (hopefully temporary) damage I did to my leather. As a general rule, I've just been idling it for a few minutes when I get home with the heat cranked up so that when I back it into the garage for the night, it's nice and toasty in there. But I've been distracted a couple of times and it's sat there running for longer than I would have liked. Oddly (and I hope coincidentally), now when I first start my engine, there seems to be a weird, very slight vibration in the drive train. I can feel it in the steering wheel and the brake pedal at stop signs/lights for the first five or so minutes of run time. Then it just goes away. It also goes away if I kick her into neutral.

These two things may be totally unrelated. I’m just about to hit 3k miles, so the vibration thing might have showed up anyway. But naturally I’m wondering if I’m doing more damage to my drive train than good for my interior at this point.

Thanks again all.

 

It would take more idle time than that to cause any problems if they would have anything to do with that.

 

I recently installed an Air/Fuel gauge, and I am surprised at how quickly the the a/f's return to optimal ( 14.7 or stoich ) after a cold start. It's not as cold here, but in less than a minute the PCM is done with the rich choking.

 

It's no problem to let it idle. big difference in a fuel injected engine vs. carb. We idle our work vehicles for 8-10 hours a day with safety lights on and the a/c. So a couple of hours to heat up your seats is nothing.

 

OK, thanks again all. I'm going to ask about the slight vibration when I have it serviced at the dealership later this week but won't be surprised if they laugh at me. Probably just normal stuff now that the engine is finally breaking in...

 

in our cars at work (police package crown vics) we have red ignition disabling buttons (now standard on all new police cars) that enable you to push the button, turn the key to the off position, & the car stays running. This way you can't steal the car until you put the key back in the ignition & turn it back tot he start position. Without the key the shifter wont even go into drive. Anyway, my point in this is that these ford V8's are beign made to idle conrinuously.
By the way, our computers, light bars, etc drain the batteris & this is why the constant idling is being required now days.

Brian

 

FYI all, I like to change my oil for the first time with a new vehicle at 1,000 miles. Some folks say it isn't necessary. I reason that a lot of metal shavings, etc, are being generated in a brand new engine, so what's 30 or so bucks with such an expensive truck? Furthermore, I decided to get my second oil change at 3k miles, just so I could stay in that cycle of 3, 6, 9, etc...

I check my oil every time I tank up (which isn't all that often anymore with a 30 gal tank and a job that keeps me on the road driving rental cars most of the time). Right before my 3k change, I had a look at the dipstick. After all that idling, I was amazed at how black that oil was - especially after only 2k miles! Even my old '94 Exploder doesn't look that black after 2k. I have no way to estimate what the idle time would equate to in miles, but it's obviously a lot.

Just goes to show that you definitely have to adjust your maintenance schedule if you're going to be idling a lot. I'm sure you all knew that but, again, was just amazed at how badly that oil was chewed up in so little time.

 

Could it be a little bow-by from new piston rings seating? May get better. LOL

 

I'm sure you already know this.....but you, nor anyone else can tell by looking at oil if it needs to be changed.

The only way to know for sure, is to have it tested.

Just because it's black doesn't mean it's not functioning at 100%.

I know, everyone likes see thru oil, I do too. But black oil is not necessarily bad oil.

 

Fair enough all - I think you're right. My only point was that 2k miles on that oil looked a lot different with all the idle time than I think it would have otherwise. Doesn't mean it wasn't doing its job - just means that there should be a difference in your maintenace plan if this is an ongoing thing. Again, probably not news to most folks around here. Just sharing an experience....

 

I should also go back to that point about checking the oil with every tank of gas. The difference between the oil check prior to the idling thing and a few checks afterwards was dramatic. One or two 30 gal tanks that included a lot of idling made a visible difference, for sure. I think that validates what I've read (here and elsewhere) about how the engine behaves differently at a low idle vs. normal running. Specifically, there's more build-up in the cylinders that finds its way into the oil system and, presumably, causes more wear than normal. But I'm sure there's also the fact that the rings haven't fully seated yet too. Again, just sharing - not trying to make a mountain out of a mole hill...