Engine Temp and Engine Wear 1

[2autoX]

Can anyone say what kind of damage is done to effectively every internal moving part of an engine when it is operated before reaching running temp?

Are the amounts of expansion each part experiences enough to create brief periods of rapid and/or extreme wear due to increased play when not up to running temperature?

Would it be best to let the engine warm up at idle, thereby allowing the engine to operate at its lowest load, or would driving gingerly speed up the rise to opererating temperature(and full expantion), and allow the engine to spend less time running at less than optimal temperature?

 

[ivymike]

Would it be best to let the engine warm up at idle

Not really, no. Excessive idling can be far worse. Just don't start up when it's so cold that the piston cooling jets (if so equipped) can't squirt the pistons.

 

[kenre]

Gentle driving would be best as the low load will help the engine warm up faster.

Ken

 

[Milanoguy]

Hi 2autoX

High dollar race engines are routinely preheated before startup to avoid the wear you speak of. This is done by using quick connect/disconnect fittings on the engine coolant hoses. The hoses are then connected to an electric immersion heater with a built in pump that heats the engine coolant to normal operating temperature. The heater is then removed and the engine is started. Here is a link to one made by Earls

http://www.earls.co.uk/qdc/03_pre-heater.pdf.A

similar process can be applied to the oil.

Air cooled piston engine engines used in propeller driven general aviation planes are often preheated using a propane powered forced air heater. Ducts from the heater send hot air into the opening that cooling air normally flows thru.

The part of the engine that is most effected by a cold start up is the cylinder bore, piston rings, and pistons. This is because the biggest cold clearance in an engine is between the piston and the cylinder bore. Preheating the engine helps put some heat(and thus expansion) into the pistons reducing this clearance..

The next system to be effected would be the valve train in an engine without hydraulic lifters.

Bye

 

[EHudson]

Cold temperature operation may allow the blow-by gases to condense in the crankcase. This puts water and acids in the oil which can lead to corrosive wear. The higher thermostat temperatures permitted with gylcol anti-freeze mixes did a lot to eliminate this in automobiles. Marine engines that are cooled with lake water or directly with sea water tend to have 140 F degree thermostats that can lead to problems. The lower temps are to prevent the build up of cooling system deposits.

Fuel economy is better when the engine cooling water temperature is about 250 F according to some WWII aircraft studies.

 

[wfowfo]

Quote:
"Cold temperature operation may allow the blow-by gases to condense in the crankcase. This puts water and acids in the oil which can lead to corrosive wear."

I thought part of the reason for warming up an engine (prior to putting it under load) was because these same gases originally condense on the cold cylinder wall, causing undue ring to cylinder wear. Is this incorrect?

 

[ivymike]

They'll stay there longer if you warm it up slowly...

 

[carnage1]

In one of my reference books I have a chart of data from a studydone by continental motors in probibly the late fifties (the book is copyright 1963). It is a 60 hour gasoline engine test with the only variable shown being tempature.
at 40F fuel was consumed at 3.8 gal/hr power produced was 26 hp and cylnder wear was .008 in. At the other end of the test temp was 180F fuel was consumed at 2.8 gal/hr power produced was 29.5 hp and cylnder wear was .0003 in.
It seems like warming up quickly would make a big difference over the life of an engine.
Also if anyone knows where I might be able to find more data on this I would be very appricative.

 

[wfowfo]

Quote:
"They'll stay there longer if you warm it up slowly..."

Are you saying that in a conventional gas engine (ie-no pre-heating features) you will get better engine longevity if you rev it up right away on a cold start?

 

[ivymike]

do you mean longevity as in "miles before overhaul" or "hours before overhaul?"

 

[ivymike]

And to answer your straw man with another one, do you think you'll get better engine longevity if you idle it for 300 hours before driving, every time you start it?

 

[wfowfo]

Miles before overhaul. I'm talking about making a family car last +200 K with minimal maintenance.
So let me repeat the question. Are you saying that in a conventional gas engine (ie-no pre-heating features) you will get better engine longevity if you rev it up right away on a cold start?
Not looking for an argument here, just clarification.

 

[ivymike]

No, I'm not saying to "rev it up" right away, or immediately do a max power run.

I'm saying that in most "cold" (15degF to 70degF) startups, you should run the engine for a few seconds (5 to 30, longer for colder), then drive it gently until the coolant temp gauge moves. The idea is to get the oil to the rings/bore and cam/follower interfaces (amongst others) before you apply high loads. "Start engine, idle for a few seconds, drive" is probably what the manual for your car says, if you have a look at it.

Letting the engine idle until the temp gauge is at "normal" will add uneccessary hours to the engine (bad for wear), may result in extra hot piston/cold block running (potentially bad for wear), may result in more rapid oil degradation due to water and corrosive components condensing in the sump, and more.