Engine preheat
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Engine preheat
Some Lyco engine recommendations suggest preheating if the ground OAT is below +6C.
Yet it is obvious that almost nobody in the UK does this, and indeed most cannot. Even most hangared owners are not allowed to use mains electricity in the hangar.
Is this a real risk?
The damage in the first few seconds of engine running must be almost totally related to the oil used. And I wonder if this is a fossil recommendation from the pre-multigrade days?
Yet it is obvious that almost nobody in the UK does this, and indeed most cannot. Even most hangared owners are not allowed to use mains electricity in the hangar.
Is this a real risk?
The damage in the first few seconds of engine running must be almost totally related to the oil used. And I wonder if this is a fossil recommendation from the pre-multigrade days?
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I reckon the recommendation is to do with differing rates of thermal expansion between the various metals in the engine. Certainly the 6 cylinder DB4/5&6 Aston engines needed preheating if the ambient temperature was sufficiently low, as the alloy block would contract faster than the steel crankshaft and 'grip' the crank.
Of course, once the engine was sufficiently clapped out and the tollerances were loose enough, the problem would go away (or be substituted for an entirely different problem).
Of course, once the engine was sufficiently clapped out and the tollerances were loose enough, the problem would go away (or be substituted for an entirely different problem).
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Only in the most dire of "gotta go right now" circumstances would I not preheat my engine. I like to see at least 50F oil temperature before I start in the winter.
That said, I NEVER put multi grade oil in my engine, I have had terrible experiences with it. So it's only fair to get the 80 grade oil to the temperature it should be, before demading it lubricate freely...
Yes, when I worked at the engine shop, we did see damage which we attributed to very cold starts, and no lubrication at the beginning. You know how it takes longer for oil pressure to indicate in the cold? It's taking the same longer for that cold oil to work under pressure, where you most need it to lubricate effectively!
That said, I NEVER put multi grade oil in my engine, I have had terrible experiences with it. So it's only fair to get the 80 grade oil to the temperature it should be, before demading it lubricate freely...
Yes, when I worked at the engine shop, we did see damage which we attributed to very cold starts, and no lubrication at the beginning. You know how it takes longer for oil pressure to indicate in the cold? It's taking the same longer for that cold oil to work under pressure, where you most need it to lubricate effectively!
Can't help mentioning the story - more or less on topic - of the high-gloss Italian car of the interbellum, that was supplied complete with, among many other accessories, two large copper tubs. In preparation for a winter ride, the owner/driver was supposed to drain the radiator in one, the oil carter in the other, and leave both basins on the kitchen stove overnight. Restoring their contents to their normal residence would ensure proper engine temperature for starting.
Must have been a Lamborghini, if it wasn't a Bugatti.
Must have been a Lamborghini, if it wasn't a Bugatti.
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Only in the most dire of "gotta go right now" circumstances would I not preheat my engine. I like to see at least 50F oil temperature before I start in the winter.
I understand that in Canada it is not unusual for cars to be "plugged in" at night to enable electric heaters to keep their engines at a sensible temperature.
The Canadian guys are best placed to answer this but I don't think it's a huge area for concern with relatively mild UK temperatures, and particularly with multi-grade oil, if used.
I can remember starting O-200s with a squirt of ether, because they simply would not start on avgas due to low ambient temperature. No hangar was available. Ether's risky if used in excess but I don't think the bottom end suffered.
The biggest issue with startup lubrication in my mind isn't cold weather - it's loss of oil pump prime with some engines (Continentals especially) if they're unflown for a period... And the attempts to start them before prime is re-established.
Whatever Lycoming suggests, don't let those knuckle heads at EASA find out!
I can remember starting O-200s with a squirt of ether, because they simply would not start on avgas due to low ambient temperature. No hangar was available. Ether's risky if used in excess but I don't think the bottom end suffered.
The biggest issue with startup lubrication in my mind isn't cold weather - it's loss of oil pump prime with some engines (Continentals especially) if they're unflown for a period... And the attempts to start them before prime is re-established.
Whatever Lycoming suggests, don't let those knuckle heads at EASA find out!
You can buy a car pre-heater that plugs into the cigarette lighter outlet,but maybe the wiring may not take prolonged use.Otherwise,use a spare battery,and jump leads to the plug.Would also be better to drain the oil and heat it prior to going to the airfield......A little `bush-craft`....
Pilot Dar (multi grade oil)
Hi There PD
I would be interested in (what your problem is with "multi grade" oil)
Preheating in the UK in nearly unheard of (and so is dilution with fuel)
As the resulting "Carb fires" are usually an insurance job i assume no one gets excited re the situation.
I did my own tests and "switched " to a 15-50 (well known make) that sounds like bell.
I noticed at least two advantages :-
Much better starts in cold weather and pressure comes up quickly.
Much better exhaust valve lubrication during normal use.
If it is really cold (as we have experienced of late) i blank of the air intakes and give it half an hour with a fan heater.
The difference is amazing, it starts on the button (if it had a button) the pressure comes up and it runs smooth at once without having to do more priming or Throttle pumps.
AS for using multi grade in "hot" weather i have to say that my T&P's are always L&H in that order and one can always "top up" with mono grade between changes.
As the Machine gets used for "Towing" the tests were for real.
I found that there was a difference between the 20w50 and the 15-50 so stuck with the latter.
THis is with a Lyc 4 potter (180hp) that needs hardly any top ups and keeps its comp's up.
I am not suggesting that this oil would be suitable for a large radial with reduction gears but would not dismiss trying it out.
I would be interested in (what your problem is with "multi grade" oil)
Preheating in the UK in nearly unheard of (and so is dilution with fuel)
As the resulting "Carb fires" are usually an insurance job i assume no one gets excited re the situation.
I did my own tests and "switched " to a 15-50 (well known make) that sounds like bell.
I noticed at least two advantages :-
Much better starts in cold weather and pressure comes up quickly.
Much better exhaust valve lubrication during normal use.
If it is really cold (as we have experienced of late) i blank of the air intakes and give it half an hour with a fan heater.
The difference is amazing, it starts on the button (if it had a button) the pressure comes up and it runs smooth at once without having to do more priming or Throttle pumps.
AS for using multi grade in "hot" weather i have to say that my T&P's are always L&H in that order and one can always "top up" with mono grade between changes.
As the Machine gets used for "Towing" the tests were for real.
I found that there was a difference between the 20w50 and the 15-50 so stuck with the latter.
THis is with a Lyc 4 potter (180hp) that needs hardly any top ups and keeps its comp's up.
I am not suggesting that this oil would be suitable for a large radial with reduction gears but would not dismiss trying it out.
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Silvaire1
I agree, I don't believe infrequent use of starting fluid is that harmful and prudent use as you mentioned is on target.
Just keep in mind it can contain as much as 60% dimethyl ether and most 4 strokes can't handle extreme pressures on ignition, especially cold. It also has no lubricating properties. Great used on high compression engines such as diesels however.
If you can wrap the cowl and preheat engine compartment while you get a coffee and do a preflight.....the engine should start with carb heat on by using the warmed air inside cowling to atomize the avgas.
Also I believe multigrade oils work well, however even if one drains the oil after flight and brings it into the camp in order to keep it warm, it does nothing for the differences in the engine metallurgy properties the next morning at startup.
As a fellow Canuk mentioned only a most dire situation on the ground would cause me to deal with a possible most dire problem in the air.
I agree, I don't believe infrequent use of starting fluid is that harmful and prudent use as you mentioned is on target.
Just keep in mind it can contain as much as 60% dimethyl ether and most 4 strokes can't handle extreme pressures on ignition, especially cold. It also has no lubricating properties. Great used on high compression engines such as diesels however.
If you can wrap the cowl and preheat engine compartment while you get a coffee and do a preflight.....the engine should start with carb heat on by using the warmed air inside cowling to atomize the avgas.
Also I believe multigrade oils work well, however even if one drains the oil after flight and brings it into the camp in order to keep it warm, it does nothing for the differences in the engine metallurgy properties the next morning at startup.
As a fellow Canuk mentioned only a most dire situation on the ground would cause me to deal with a possible most dire problem in the air.
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The damage in the first few seconds of engine running must be almost totally related to the oil used. And I wonder if this is a fossil recommendation from the pre-multigrade days?
Preheating is not a "fossil recommendation." If you care about your aircraft, it should be mandatory. Anytime you're below about 40 degrees F, you should be preheating.
Preheating isn't just about keeping the oil flowing. The entire engine should be preheated, not just the oil.
Aren't there heating devices which go into the oil dipstick hole?
The poor boy engine heater is a work trouble light laying on top of the cylinders, with a blanket over the engine.
Combustion space heaters with a hose to the engine compartment also work well, but it's far better to have the engine stay preheated all the time, rather than start heating the engine before the flight.
A "fossil system" is oil dilution, which was factory-installed in some aircraft, standard in some, optional in others. It involved running avgas into the oil prior to engine shutdown, in order to reduce oil viscosity. In theory, the avgas would vaporize and allow the oil to return to it's original state after the next engine start.
Dilution changes oil chemistry, leaves deposits, and adds a solvent to a lubricant: never a good solution. Nearly all oil dilution systems have been removed or deactivated today.
Removing oil from the engine and keeping it warm, then returning it to the engine is a necessity when temperatures will drop enough to congeal oil. This still doesn't heat the engine throughout.
The engine is made up of various metals, each of which have different expansion rates. The entire engine should be heated uniformly, as best able, prior to engine start, for cold weather starts. Adding heated oil to the engine doesn't accomplish this, but does at least get oil flowing during the initial start, which is better than not having the oil flowing.
How did my 1200 VW work so well
Interesting thread this, but it got me thinking how my old VW 1200 (1955) Beetle engine never needed any special treatment to go to work every day.
On some days the car would look like an huge snow drift and you may have to "heat" the key to unlock it but as long as it "cranked" (6 Volt remember) it went and the oil light would go off in a second.
Now this engine was very similar in construction to what i fly behind today.
Steel crank,Allui or Mag alui crank-case,steel cylinders,Steel rods,Allui pistons,allui heads with alloy bronze guides and normal valves,operated by steel camshaft and followers.
In those days (mid sixties) you had the option "like today" of mono grades Castrol 20 30 40 XL20-50 or the "new" Castrolite" (which i used).
The hand book suggested various grades depending on the average OAT but in the UK the 30 or 40 would have been normal.
That engine did over 150,000 miles before a teardown to replace a fibre cam drive that got oil soaked and failed. (a known problem)
Years later i did hundreds of hours behind all sizes of VW engines that did not know they were flying (nor did they care).
The question is was the VW just a very good engine that could run in the Artic or the Desert or was it having the correct lubriction for the application that made the difference !!!
On some days the car would look like an huge snow drift and you may have to "heat" the key to unlock it but as long as it "cranked" (6 Volt remember) it went and the oil light would go off in a second.
Now this engine was very similar in construction to what i fly behind today.
Steel crank,Allui or Mag alui crank-case,steel cylinders,Steel rods,Allui pistons,allui heads with alloy bronze guides and normal valves,operated by steel camshaft and followers.
In those days (mid sixties) you had the option "like today" of mono grades Castrol 20 30 40 XL20-50 or the "new" Castrolite" (which i used).
The hand book suggested various grades depending on the average OAT but in the UK the 30 or 40 would have been normal.
That engine did over 150,000 miles before a teardown to replace a fibre cam drive that got oil soaked and failed. (a known problem)
Years later i did hundreds of hours behind all sizes of VW engines that did not know they were flying (nor did they care).
The question is was the VW just a very good engine that could run in the Artic or the Desert or was it having the correct lubriction for the application that made the difference !!!
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Two main things have changed in aero engines lately: multigrade oils (which are not so viscous at low temps) and most "advanced" owners have the "Skytec"-type high speed starter motors which crank the engine 2x to 3x faster than the old style starters.
In the UK, largely due to airfield/hangarage politics, almost nobody has the facilities to preheat engines.
Yet there is no evidence that UK based engines are getting trashed at great rates. I send my oil analysis to a US lab and my metal numbers are in line with the US averages.
What I do see regularly is people unable to start their engines. This is probably a combination of using straight oil, knackered batteries, and knackered starter motors. But that is a separate issue to doing damage to the engine by starting it at say 0C without a preheat.
In the UK, largely due to airfield/hangarage politics, almost nobody has the facilities to preheat engines.
Yet there is no evidence that UK based engines are getting trashed at great rates. I send my oil analysis to a US lab and my metal numbers are in line with the US averages.
What I do see regularly is people unable to start their engines. This is probably a combination of using straight oil, knackered batteries, and knackered starter motors. But that is a separate issue to doing damage to the engine by starting it at say 0C without a preheat.
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Lately is a relative term, apparently. Multi-grade oils have been in use for several decades now, and offer significant advantages over single-grade oil.
One needn't have a hangar to preheat an engine.
The spot numbers for your spectrometric oil analysis aren't nearly so important as the trends.
"Getting trashed" or not isn't really the issue. There's no question that preheating reduces the amount of warm-up time required, and that it does reduce wear, every bit as much as preoiling reduces wear. Whether your engine gets "trashed" or not is another matter.
I'll have to add this to the list of "UK Uniqueness," though. Carburetor heat, mixtures, low altitude flight, and apparently cold weather operation all work differently within the geopolitical borders of the UK...an apparent conundrum in the aviation world from which the remainder of the globe could apparently learn aplenty.
The rest of the thinking world uses any number of available commercial heaters to preheat the engine on the ramp, where no field-supplied power source is available. Portables such as the Red Dragon work just fine.
12 Volt D.C. Self Contained Red Dragon Engine Preheaters
One keeps the cowl on, with insulating blankets, and experiences no damage.
n the UK, largely due to airfield/hangarage politics, almost nobody has the facilities to preheat engines.
Yet there is no evidence that UK based engines are getting trashed at great rates. I send my oil analysis to a US lab and my metal numbers are in line with the US averages.
"Getting trashed" or not isn't really the issue. There's no question that preheating reduces the amount of warm-up time required, and that it does reduce wear, every bit as much as preoiling reduces wear. Whether your engine gets "trashed" or not is another matter.
I'll have to add this to the list of "UK Uniqueness," though. Carburetor heat, mixtures, low altitude flight, and apparently cold weather operation all work differently within the geopolitical borders of the UK...an apparent conundrum in the aviation world from which the remainder of the globe could apparently learn aplenty.
The rest of the thinking world uses any number of available commercial heaters to preheat the engine on the ramp, where no field-supplied power source is available. Portables such as the Red Dragon work just fine.
12 Volt D.C. Self Contained Red Dragon Engine Preheaters
One keeps the cowl on, with insulating blankets, and experiences no damage.
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One 40 Watt light bulb in a car mechanics inspection lamp slid under the cowling for a couple of hours before the flight.
Th crankcase and sump and made of aluminium, and I wonder if there is a product based on a heating element which could be attached to one of the (many) screws which are all over the place. Such a heater would be left permanently attached, and would be wired to a connector somewhere. A small device could easily dump 100-200 watts into the engine in this way.
Of course it depends on how much one is trying to heat the engine up by. The UK is rarely that cold... -2C right now (Sussex).
The installation would have to be signed off - a Minor Alteration would probably do.
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You need a 110V 60Hz preheater. Use a stepdown from the UK supply.
Don't mess with other oils. Stick to the book. You can start them when new in an emergency but even then you gotta sit in 'em for 15 mins to get the temp up before thottle. Not rocket science.
When you sit in 'em during warm up NO THROTTLE.
Engine prime with the ignition off...please note...turn the prop 12 full turns....please note..if uncertain DO NOT DO THIS.
Don't mess with other oils. Stick to the book. You can start them when new in an emergency but even then you gotta sit in 'em for 15 mins to get the temp up before thottle. Not rocket science.
When you sit in 'em during warm up NO THROTTLE.
Engine prime with the ignition off...please note...turn the prop 12 full turns....please note..if uncertain DO NOT DO THIS.
At my home airport, Helsinki-Malmi (minus 20 C yesterday) winter ops would be impossible without preheat. The airport provides electric outlets (230V, 16A) on pylons, adjacent to about 50 of the parking spots on the apron, for a monthly charge. What we use for the Cessnas which are not hangared - space is scarce - is 1200 W Defa car heaters placed inside the air intakes. If itīs really cold, 2 heaters per aircraft. Going on all night and all day. It works, too. Since 1969, in fact 