Does warming up harm your engine?

[Cali 911]

I have heard not to let your Porsche idle to warm up, is this true?
If so, what does it harm?

[pozee]

Depends on your particular 911's oil pressure at idle.

Letting it idle for long periods at extremely low pressure is the issue.

[Tyson Schmidt]

Surprisingly the cylinder head temps get pretty high idling in place for long periods, and instantly come down when the motor is revved.

Because the motor is under no load, there really isn't that much damage going on period, but it's not an ideal situation for the more dynamic way an air cooled motor cools itself.

[Gunter]

Engines don't like idling for different reasons.
Car manufacturers recommend to get going within about a minute of cold-start putting light loads on the engine meaning: No high revving until warm/hot.

[Zeke]

Some 911's aren't that drivable right after firing them up. CIS comes to mind as well as MFI. I usually sit for 30 seconds and then roll off easily not revving over 3k for a couple miles. I don't get aggressive until the oil shows some heat on the gauge. Some say to not drive hard until after 20 minutes.

[RoninLB]

manual throttle is a great install

[Paulporsche]

Warming up the engine by idling increases our dependence on fossil fuels, needlessly takes money from your wallet, adds contaminants and heat to the atmosphere and puts undue wear on your engine's camshaft (so I've been told).

[RSTarga]

start it up, give it a minute and then take it easy for the first few miles. Idling is not very efficient and tends to build up carbon deposits in the combustion chambers, at least with MFI or carbs. Some of the new cars run very clean , but still it is a waste of energy.

[old man neri]

Warming up your engine via the idle takes a lot longer to get things warm thus your engine is running cooler for a longer period of time. I don't know if that has anything to do with it.

I just let it idle, then hold it at about 2K until it's smooth, and then I drive it gently, no more than 3.5K. I am also careful not to bog it with needless low revs when cold.

[Rrrockhound]

This is the lamest old debate ever, IMO.

When it's 0 degrees F outside, I'm letting the car heat up so I can drive without my breath freezing on the windshield, I don't care what anybody says.

[Cali 911]

I have owned this Porsche (my first one) for three years now,and I had no idea. I do usually take off after a minute or so, but sometimes let her sit for a bit longer. Thanks for the info!

[James Brown]

I'm with Rrrockound, l let it warm up (2k rpm) for 30 min. when it's fricken cold outside! heat is slow to come in the cab. also, keep in mind that just warming up the engine does nothing to warm up the transaxle, breaks, and wheel bearings so l still go slow for a few miles. Then, let er rip!

[Hugh R]

I fire it up in the morning, go back inside and get my traveling coffee cup and go. I don't get on it at all until I see the temp gauge start to move.

[s_morrison57]

NICE RIDE
I have a 87 930 that I idle for about a minute or so, i take it out if the garage and park it in the driveway for about10 mins. before I take it out , low rev til the oil is warm. its a thing I do with the race cars and its called heat soaking , let the parts warm up and expand with no stress and let the heat soak into the parts with no stress so they expand with out the duress of driving it now. after that when the oil is hot I boot it , the secret for racing a liquid cooled car is hot oil cool water. let your engine componants expand with out the durress before you stress it

[s_morrison57]

when i park it its turned off

[spuggy]

Short answer to the OP's question is that the owner's manual specifically states you should not idle the car to warm it up, but should drive it instead, keeping the revs down and load light until it's hot. At least, the one for my car does. Any more questions?


I believe that oil flow is the absolute lowest when the oil is thick and cold. Pressure is relatively high, but flow is at the minimum.

So idling when the oil is cold means that the oil flow is at the lowest it'll ever be. Idling is when the car is making the least heat (no work) - so it'll take longer to warm up as well.

A long time ago, I was taught that you started a vehicle, ran it long enough that you could pull away without sputtering and knocked any manual choke off as soon as possible. It's worked pretty well for me for many years.

Like some others here, I fast-idle for a minute or so to get some heat into the top-end (this is enough to open the internal engine thermostat maybe 3-4 times, which you can see with a 140 PSI pressure gauge), and then take off, keeping revs down and load light until the oil starts to warm up.

On the 911, I use a "3000 limit until 80 degrees, 4000 until 190 degrees, no slogging ever, no boost until 190 degrees" regime.

[timc]

I fire it up, hold at about 2k for 15 - 30 sec's then drive off, not exceeding 4k until I get the oil up to normal temp. I never ever let it sit and idle. .

[SteveinTO]

Reading this thread it occurs to me:
1) the cylinder heads heat up real quick from a cold start;
2) the oil will take forever to heat up from cold idle, and;
3) your heater should blow hot air almost immediately.

Start up cold and drive away in 20 seconds. Don't hammer it until the oil temp comes up.

[runfaster]

Start it up and give yourself enough time to roll a fatty, then hit the road. At least that's what the old hippie VW repair manual says.

[michael lang]

I personally don't think there is anything wrong with letting it idle for a few minutes before driving away at a true cold start. I will let it go for anywhere from 5-10 mins at most. I know the trans fluid doesn't heat up. I'm more interested in having the engine getting some oil running through it before I start driving. Once the oil gauge starts showing some rise in temp, then I'll pick up the pace. Been doing it that way for almost 20 years of driving. No failed engines yet.