Technical Letting an engine idle?

One thing that has not been mentioned is the impulsiveness of the cam at low speeds. If you have ever tried to move a cam shaft while replacing a timing chain, you may have encountered this. Prolonged low speeds ( idling ) will tend to stretch the timing chain.
Most engine manufacturers will tell about not idling long periods. A lot of equipment have “ high idle” mode on them for a reason.
Idling a while will not “destroy” an engine… but the discussion was meant to determine if long periods of idling was good or bad for an engine. And what happens in an engine when it idles……long periods.
So far some good points.






Bones

 

Saw a post somewhere that was talking about cop cars. Poster claimed that every hour of idling was the equivalent of 33 road miles of engine wear.
I have no statistics to back that up.

 

I'll take a wild guess that far greater destructive forces are applied to the chain & gears c@ 5000 rpm than @ 600 rpm ..

 

My diesels idle until EGT is cool,bad on turbo bearings to shut down when hot . Parade duty or funeral escort duty on an old Harley will truly test how good of shape the old mechanical stuff really is . Right inner leg touch the rocker box after 20 minutes idling , and you will never allow it to happen again ..

 

I once got stuck in my 67 chevy wagon at the end of my friends long farm driveway, big blizzard happening, temps expected to drop to about 20 below, I had a full tank of gas and I knew it would probably not start the next day so I left it run all night. Got out there the next morning and the whole car was just a big snow drift with puffs of exhaust coming thru a hole in the snow. After we dug it out she didnt smoke any worse than it did before

 

That would mean idling is TWICE as good for the engine, rather than driving...even at the speed limit, after an hour, you would have 65 road miles of engine wear.

 

Electric radiator fans..... and alternators....

Engine driven fan and a generator don't work so well at idle speeds.

I've been to 2 separate parades where a classic car overheated and puked a nice big green puddle in front of everyone.

 

Back in the seventies, I was the police mechanic and police cars were junk by 75,000 miles. Not totally sure why, but I would have to guess sitting around idling was a factor!




Bones

 

My wife volunteers at our town library and she "volunteered" my truck to carry banners for our town celebration parade. I did it for 3 yrs. It didn't seem to hurt anything.

Gary

 

With the old mechanical diesel trucks, we never idled them up. That all changed with the computer controlled engines, the makers started saying idling was bad for the engine, if you had to idle to bump it up to 700 rpm or more. In 40 years of fooling with diesels, the only engine I ever lost wasn’t due to excessive idling, it was due to excessive soot buildup from the egr system. I idle every night, I like heat in cold weather and AC in hot weather!

I have let my pickup idle for two or three hours at a time with jumper cables attached trying to start off an old diesel truck more than once. Never seemed to affect it, other than the gas gauge dropping!

 

This is funny!!

I live pretty far north in Canada and I shut my stuff off every day….never had an engine “freeze solid”. It’s heating my igloo that’s the challenge, I hear next year we may get running water….

 

There were movies?

 

I agree. Make all those politicians walk.

 

If nothing else, allowing an engine to just idle is a sure recipe for building up acids and corrosive compounds in the oil, which will attack the bearings and assorted other metal surfaces in an engine. Not a wise choice. You may have your reasons for doing it, and that's your business. But thinking that there is nothing wrong with it is ignorant.

 

We have half a packet of smokes and wearing sunglasses. Hit it Elroy!

 

Well in those situations I hope you weren’t “idling”!

 

Got a call from a buddy asking I look at his OT econobox. It seems he stopped at the home of some friends who were having a party. He was only going to stay for a minute so left his car running. The minute turned into hours. A lot of hours. So many he wasn't sure how long it had been. There may have been alcohol involved. When he went out to leave, he noticed a strange, burned smell. His car wouldn't start but the switch and the lights were on. He opened the hood and was greeted with a blast of fumes from melted plastic and metal. Even in his somewhat impaired state, he knew he was screwed.
When I looked at it, there was not a drop of coolant to be found. The oil had turned to tar. The plastic parts on the motor were melted. It was seized tight. He didn't admit to any history of cooling system problems. My only guess was a stuck thermostat but I suspected he may have left out some history.
Got the car to my shop and put a junkyard motor in it. Swap went fine, motor started and ran fine. Put it in gear to back out of the shop and nothing. Drive and reverse were absent. Did I not get the converter engaged? Did I crack the pump? Nope. That thing was so thoroughly fried that it cooked the trans and the motor.
So, in his case, leaving an idling car was not a good idea.

 

Huge warranty problems idling Diesel engines lead to the development of idle kickers and exhaust back pressure devices to prevent wet stacking and keep the oil temperature up. No diesel manufacturer recommends excessive idling. Messes up the after treatment, too. May have worked decades ago, but modern diesels have retarded idle timing to meet NOx emission standards.

Ford and others had big issues with cam failures on gas engines in ambulance applications. Excessive idling doesn’t support the hydrodynamic film when the oil gets hot and thin.

So it’s a problem both hot and cold.

Used to do 1000 hr tests of F250s with the old E4OD transmission. The transmission never made it over 350 hours.

 

First brand new car I bought was in ‘85, read the owners manual cover to cover.
“Standard” oil change was some number, probably 3k miles then the disclaimer about “severe duty use”. Driving in (can’t recall) conditions and yes I do recall one of the “severe duty uses” was extended idling.
I’ve gotten a lot smarter though over the years, only time I pull the owners manual out is to remind me how to reset the “oil
Life” indicator

 

I have to agree with this statement & the best way to prove it to be true would be to do an oil analysis. Take a sample & send it to a quality lab like Polaris Laboratories. You can acquire a sample bottle with paperwork from several places on the internet.

God Bless
Bill
https://www.jalopyjournal.com/forum...ar-transport-hauling-open-or-enclosed.614419/

 

I've had cars that didn't like to idle long when stuck in traffic, but mostly because the engines were high horsepower builds, and they just didn't like all that idling. But had others that could idle for extended periods and not miss a lick. It really boils down to the way the engine is built, and what it was built to do.

 

I think the key thing here is whether the "idling" engine in question is one that always operates at/near idle when in use............or one that goes thru all the normal variations in rpm with daily use and only occasionally is used in an extended idling situation.
I will say that there are things which could prove somewhat detrimental to even the engine that normally uses all the rpm ranges. Every engine (especially hot rod engines) has different situations to contend with. Variations in how the engine is tuned could cause plug fouling and subsequent carbon problems.........but it would be on a case by case basis. 100 engines might have no adverse affects and then ten hot rods would. I would say that sitting in long lines of traffic daily on an Xway would not be good for an engine and eventually have some ramifications. Not total failure, but probably shorter length of service and probably the need to replace some parts sooner.

 

remind me not to be in a parade behind you

 

Car trips to the Jersey shore with my family in the 1950's often had long traffic jams...In hot weather the shoulder of the road had cars with the hoods open and a steam cloud...

 

My grandpa told me a story one time... The neighbor across the street had a 57 Ford flip top. He had a dead battery one morning so grandpa jumped it so he could go to work. He let it idle at work all day, then got home and let it idle all night. Apparently he couldn't afford a new battery so he did that for a week or so. Car ran 24/7 for a week until he got paid.

 

JD, thanks for the correction !

 

Engines are happier under a load of some kind. Doesn't have to be a lot, but more than their reciprocal mass. And yes hot enough to lose as many spent gases from the oil and condensation as well. See your retailer for details, ask for senior discounts

 

1957 Long Beach, Calif.

Hello,

Our dad used to go out to the garage to warm up his big Buick sedans. He would get completely ready for work, meaning, fully dressed and ready to go. He would pop in a couple pieces of toast and get his coffee ready. Then, he went out to the garage and start up his Buick sedan. By the time he was finished drinking his coffee, eat his two pieces of toast, the car was ready and warm with the heater going.

He had been doing that procedure since he used to park his 1949 Buick Roadmaster 4 door out on the street and do the same thing. We thought it was funny to have the Buick running on the street, but in looking back, it was 1948-53 for his Buicks to be on the street and no one stole cars in our neighborhood.

Two pieces of toast and black coffee? Well we asked him one day and he said that he did not want our mom to wake up and fix him breakfast (50’s family). She fixed us fabulous breakfasts, but, our dad ate breakfast with some friends in Los Angeles at a local café. Think old style café with red naugahyde coverings and red Formica table tops.

As little kids, my brother and I ate a fabulous lunch at the same counter and booth of this old cafe, on one of our Los Angeles road trips. Their homemade fries were outstanding, as we each got our own red plastic basket with paper inside holding the fries... yum... Now I am hungry.

Jnaki

The 1951 Oldsmobile Sedan in the two car garage in 1956.

The warm up was his way to get his big Buick comfortable to drive from Long Beach to Los Angeles at 5:45 am every day. He like warmth in his cars. But, we had the same garage in our last Westside of Long Beach house. We started the 51 Oldsmobile Sedan and 58 Impala up when they were parked on the left hand side of the two car garage. By the time we moved the cars over in the garage to back up out of the driveway, the cars were ready to go.

The 1957 Buick in the driveway and the 58 Impala in the garage, (chrome roof top vent showing)

There was never a time when we idled for any longer period of time… why? The oil pressures were fine, the motors purred like they should and we did not have any stumbling problems from any car inside of that garage.

Even when my 1940 Ford Sedan Delivery was in the backyard parking area, by the time I backed up to get on the concrete driveway, the Flathead motor was warm and ready to go to school or our coastal surf trips.

With the gas costs, as low as they were back then, we still would not waste any time idling. Now, with the years of gas crises, long waiting lines, short startups and moving along is the norm. These days with super high cost of gas and the modern motors, there is no need for long warmups. A simple idle and back up to the street is all it takes for a normal running high performance motor. (or even a low performance motor)... YRMV

 

The engine in my Pontiac is well over-cooled in terms of radiator capability, water pump and fan.
At 150 RPM in gear, it'll idle for a reasonably long time before starting to get unhappy. It's got about 20psi oil pressure when hot at that speed and it's such a low compression engine with soft valve springs it'll do it.

The problem I have idling for long periods is that the burn isn't energetic enough because it doesn't like to run lean at idle. That by itself isn't so bad but the oil that gets by the rings doesn't get hot enough to burn and it'll oil up.

That and if it's sitting in hot traffic at a standstill it enjoys boiling the gasoline in the fuel line as it passes under the motor. That had resulted in a lean running condition which makes it heat up significantly.

But in overall terms of harm? Well yeah, it's running so it's wearing out and using fuel. Exercises the thermostat though.

 

Truckers do idle for hours, but they have diesels and will go 1 million miles before a rebuild. Water pumps and generators don’t idle they run at a higher rpm. That said I don’t know if idling will hurt or not, but I don’t idle more that needed.