//// cold engine driving - how hard is too hard to push it? ////

Hi All,

With the weather getting even colder , I was wondering how hard can you push a "cold" engine without damaging it?

FWIW- these are the rules I typically set for myself for driving a cold engine ...

I typically start the engine and let It run about 30 seconds ( time passes quickly here since I am putting on seatbelts, setting radio station , organizing the car etc...)

I drive easy in lower gears until the engine gets to about 160 degrees before even using 5th ( the owners manual for my 1993 w250 pick up with Cummins diesel I think recommended that practice ( not using overdrive until stuff warmed up) so I carried it over here.... rpms are typically under 2000 rpm .

If it is really cold out I admit I do still put the heat to max but I do leave the fan speed at 1 so as not to take too much heat from the engine until it warms up...

I try to limit boost to 4 psi or under so as not to stress the engine unduly when cold.

At what temperature can you start pushing the engine harder? ( is there a chart of sorts showing max recommended engine output ( as a function of boost or other measurable parameter) vs engine temp?

In summary .... how hard can you push a cold engine before causing undue wear and damage?

Thanks

Andrew

Ps - yesterday I stopped at a rest area to sleep for about 3 hours ... when I woke up and started driving again the ScanGauge indicated a water temperature of 100 degrees... I drove on the highway at 45 to 50 mph (speed limit 70) until the engine reached a temp of 175 before picking up the pace... needless to say there were some unhappy campers passing me .... I did have 4 ways on ... I figured I'm not going to jeopardize the car by over stressing it when cold ....

You're way easier than I am. I take it easy for a bit, but after just a few minutes or a very few miles it's not even a consideration.

If I think about it, I shift around 2500rpm until the temp gage gets to the top of the 3 lines on the left, then around 3500rpm until it's vertical.

How much wear and tear can you save a car that's survived 17 years and 300,000 miles? It's probably been pushed harder in colder weather and hasn't self-destructed yet. I think you're over-thinking things. Driving 25mph under the speed limit on the interstate is probably more dangerous than using 5th gear below 160 degrees.

pretend there is an egg under the pedal. don't break it. half RPMs for a few minutes. once things are properly lubed with good up to date oil, go drive normal, just dont give it 100%, like maybe 75% until it's nice and hot.

I try to keep rpm under 3000 until the temp gauge starts to move, which is usually 2-3 minutes.




I remember once when I was an apprentice we had a work truck... it was -30s and we were late. idled it for about 8 seconds in the morning while we scraped a 4x4" patch of ice off the windshield then straight to the floor till we got to work. I still see that truck (topkick duramax) driving around. gotta love those oil patch trucks.

Andyinchville1 said:

Ps - yesterday I stopped at a rest area to sleep for about 3 hours ... when I woke up and started driving again the ScanGauge indicated a water temperature of 100 degrees... I drove on the highway at 45 to 50 mph (speed limit 70) until the engine reached a temp of 175 before picking up the pace... needless to say there were some unhappy campers passing me .... I did have 4 ways on ... I figured I'm not going to jeopardize the car by over stressing it when cold ....

Click to expand...

Yeah - that's way more gentle than I've ever thought to be with my car, even the new Mk7.

If the car is anything above stone-cold (sitting overnight and coolant / oil dropped to ambient temps), I just jump in and drive. If it is cold, even sub-freezing, I'm gentle (shift before 2300rpm, try to avoid more than half throttle)....but that lasts maybe 3-4 minutes before I start getting more aggressive. I mean, that's what that "5" in the 5W40 oil is for, right?

Start engine, snap seat belt, put in reverse to back out of spot, put in first gear proceed down my drive-way shifting to 2nd and at the end of the 450 foot drive-way, I go back to 1st before hitting the county road. Then I proceed on going thru the gears ............. never worrying about lubrication as it was there within a split second of cranking the engine over to life!


Dive more, worry less!

I start the engine, and drive away pretty much right away... I usually buckle my seatbelt and check my mirrors, so as long as that takes.

I like to keep it above 2500 RPMs but below 3000, so that the afterglow is switched off, so for me since I am very near a two-lane highway in the morning I run down that in 4th gear at about 60 for the 2.2 miles until it merges on to the Interstate. Then it is hammer down, shift to 5th, and I am off and cooking. Usually a sprint to 90+ on the empty highway for a few miles at least, then back down to 80.

I do not turn the HVAC blower on until the temp gauge is in the middle. I grew up with air-cooled Volkswagens, so I know what driving in winter is like with poor or slow heat, it is a non-issue for me. And my wife has been "trained" in this manner, too, although our Passats warm up MUCH quicker than the ALHs and our old AHU did. The older [prechamber] VAG diesels warmed up faster too. They also used more fuel. We often joked about how the 2004 Passat at 80 is consuming the exact same amount of fuel the '91 Jetta did at 80. That is a pretty good claim for improvement in technology. A 2.0L 136hp engine moving 3400+ pounds of car through a slushbox and using no more fuel than a 1.6L 52hp engine moving 2600+ pounds of car through a manual transmission.

The newer DPF equipped cars I would perhaps be a little easier on them. I tend to be easier on our Sprinter when cold due to this, but it seems to get up to temp VERY quickly since it has a fuel fired Webasto on board. On a single digit morning it has warm air at the vents in about 45 seconds.

I have always been a " get in, start it up, get ready, and go" person. The oil (5w) means it's everywhere it needs to be in under 15 seconds. The most idling I will do is to scrape the snow / ice off the windows while the car is idling. The 2000 won't even make good heat until you push it, and the 2015 isn't much better (although the electric heater helps the interior).

Up the hill in 1st gear, 3/8 of a mile on a dead end dirt, usually 2nd, an easy drive a mile and quarter to the two lane highway. A quick check for troopers, and it's a second gear hole shot, hammering gears until 80mph, then settling in to traffic speed.

I'm more concerned about the auto transmission than I am for the engine to warm up. I usually don't let it idle for more than a minute or two before taking off. Speed limit is 45 as I pull out of my parking lot.

The owner’s manual advises how to drive when the Cold Blue Thermometer is lit. Follow the advice of the engineers, as they know more about the design of the engine then any of us

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