Hey all,
I read in my new Ranger's owner's manual (4X4 XLT Supercab 4.0L) that it is not necessary to warm up the engine on cold mornings. I read somewhere else that it's even bad to warm up the engine by letting it idle for 5 or so minutes. What's the consensus on this? If it's 25 degrees out and ice is on the hood should I just crank it up and take off? What's the engineering rational behind this?

Thanks!

Tim

 

I don't think 5 minutes will hurt anything if so then every time I stop at a stop light I am causing damage to my engine. I think it only becomes a problem when you let the truck idle for 10-20 mins. If there is snow or ice on my windows I usually start my truck and then I scrap off the stuff while the truck is warming up. If there is nothing on the windows I just drive off without warming the truck up

 

Actually, I don't think that it is necessarily "BAD" to warm up the engine. But, with all multipoint/multiport fuel injected engines, the fuel mixture is metered with incredible accuracy & precision, as compared to carbs of decades ago. So, there is significantly less risk of engine damage due to flooding, and "washing down" of the cylinder walls & rings from an over-rich condition. So you CAN just basically start the engine, and go. Or not. But warming it up should be no more detrimental to any one engine than any other engine.

 

So, warming up an engine has to do with gas mixture? I always thought it was to let the oil thin out before speeding up the pistons. If you didn't warm up then there was a risk of excessive and rapid wear of the piston rings. Just goes to show y'learn something new everyday!

Thanks guys!
Tim

 

Carbs.... Decades ago ?!? Your makin me feel old here.

 

My personel feeling is to let it run for a minute or two and then drive it easy the first few miles, the colder it is the easier I am.

 

Hey mathelm, don't feel too bad. BOTH MY CARS HAVE CARBURETORS!! Your right ... I just made me feel old....

Anyway, TimRob, you are right, and "Ken00" makes an excellent point. You don't want to flog the throttle if the motor oil is like ZERO degrees Fahrenheit. That is indeed a large part of the equation. But, the "fuel mixture" part of the equation has been pretty much eliminated by today's very well controled fuel injection, which was not the case ... um ... like ... decades ago. SORRY MATHELM!!

 

Hi Tim (and Ken, and V6RL, and GP, and John-boy, Mary-Ellen...)

I too read about the same thing you did, probably 15 years ago. So, just to refresh my memory, I Googled the topic and found out the logic behind not warming-up.

The goal is to warm-up the engine as quickly as possible to tighten-up the tolerances throughout the engine. Simply speaking, the fastest way to do this is to drive it gently UNDER LOAD. Idling cold allows the loose tolerances to hang around longer, allowing more “slapping” of metal (exaggerated, of course) and “richer” fuel mixture to seep past the rings and contaminate the oil. As my buddy V6RL is well aware, fuel injection’s precise metering ability hasn’t changed a cold engine’s need for a rich mixture.

Significant? I’ll agree that’s it probably not. But why waste gas when you can get the desired result faster by simply starting up and going? As soon as I have oil pressure (like in 2 seconds after starting), I’m off.

Something else I found in the Googling was that just because the oil is a little cold, it doesn’t mean it’s protecting any less well than when hot. Also, the oil takes WAY longer to come up to temp than the coolant, which I’ve confirmed in my other vehicle. It has an oil temperature gauge (those wacky Germans), and it doesn’t MOVE until the coolant has been fully up to temp for like 2 or 3 minutes (or more). This tends to prove that 1, 5 or even 10 minutes of idling does little to help the cause, if the cause is to warm the oil. It DOES let the driver hang-out in the warm house longer, though.

Start it, put on the radio and go. Don’t rev the crap out of it until it’s fully warmed-up, and you’ll be fine.

Mike

 

Much agreed!

 

I just installed new indiglow gauges on my truck, and it just started getting cold here a couple of weeks ago. I have no choice but to let my truck warm up, or else my gauges stick. It does this if I am at work and the truck is outside all day. But I can get in it at home (where it is in the garage over night) and they work fine. Before this started happening, I would usually just get in the truck and go and I would take it easy until the temperatures came up in the truck.

Bobby

 

for 5 min yes it is bad.... have u noticed that it takes forever to warm your car up just idleing........ and driving it takes like 3 min...... in my truck it takes almost 20 min in 30 degree weither to warm up