Why should you preheat the engine in winter?

[dave_091]

I've found a great article written about engine preheating on cool days.

It mainly states that having warm oil does lickitty squat for your engine when it's cold nowadays due to multi visc oil. The problem lies in the shrinking and expansion of dissimilar metals. The crankcase shrinks around the crank possibly causing zero clearance in the bearing. It doesn't matter how warm your oil is, if you have no clearance in your bearing the oil ain't getting in there. Therefore, it's of highest importance to preheat the entire block, not just the oil.

There is a lot more written in the article. Have a gander, it might save some hours on your precious engine!

http://www.avweb.com/news/maint/182846- ... directed=1

[Colonel Sanders]

If you ever watch Ice Pilots, you can see that
in cold wx, you can't even pull the prop through.

PS In the old days, there was this thing called
"oil dilution" where you added gas to the crankcase
to try to thin out the straight grade oil. But with
multi-viscosity oil, that's really not an issue any more.

Anyone that flies in winter should be running
multi-vis oil. Wasn't there a 337 that had an
engine failure because they were running straight
grade in winter?

All too often, people pre-heat the gasoline and
get a good start, and think their engine is happy.
Ain't true. Hell, you can start it with ether if you
want.

[CID]

I assume you're talking pistons. Turbine engines have minimum oil temperature limitations for starting.

[GA MX Trainer Dude]

In all my time in the cold I do not ever remember only heating the oil!! On aircraft like the DC-3 etc. that had separate oil tanks that were usually aft of the firewall we has two ducts from the Herman that were used. One went into the engine side of the firewall under those nice oil soaked engine tents - the other went up into the wheel well to heat the oil in the tank. - Please remember on the -3 to ensure the landing gear selector is down and the hydraulic lever is correctly placed to allow the heated hydraulic fluid expansion to flow back into the tank. Otherwise you will blow a hydraulic line in the closed system!!

We used oil dilution and heat to thin out the oil for 2 reasons. The first was to ensure the ugly thick oil would flow through the engine oil passages and actually lubricate as required. The second which is also important was to prevent the oil lines and oil cooler from excessive pressure as the engine started and warmed up. The pressure side had some protection with the oil pressure relief valve - but the oil scavange system - which had about 120% flow capacity compared to the pressure pump - had no system protection and oil pressure would rise to the point where it would rupture the oil cooler or blow an oil line.

In comparison the dinky toy airplanes with wet sumps were easy - shove the heater in - and warm up until you can feel the engine being warm by a hand through the cowling. The key element here is having sufficient BTUs to do the job!! We found it cheaper in the long run to do it right with the hot air hermans than using the electric or propane heaters - but sometimes you don't have much choice. Some of our Cessna 185s' had oil dilution installed - and were preheated by the use of a small electric car type heater inserted into the engine compartment. Depending on the temperature - the amount of wind - and the heat retention ability of the engine cover - they would often be just enough to get a satisfactory engine temperature to start. Pretty marginal at -40 but we did it - and I don't remember any engine failures as a direct result of cold starting. I seem to remember a maintenance directive (Company) regarding the special procedures for cold weather operations and the oil dilution requirements. They were extensive and meant a lot of extra work for all of us.

We used oil dilution throughout the summer as well - that was to keep the oil system clean - otherwise after 5 or 600 hours without dilution the first few times you used it - maintenance would have to pull and clean out the oil filters as the fuel loosened up the carbon and crud inside the engine - depositing it in the oil filter - and on occasion under the oil pressure relief valve which would give you a low oil pressure once you warmed up the engine.

In addition you needed to pay very close attention to the fuel pressure when diluting. You would get a drop in fuel pressure when the dilution valve opened and when you were finished you need to see the rise in fuel pressure when you shut the valve. No rise means the valve is still open!! Yes it has happened - we had a single otter that this happened to in Baker Lake. The engine was diluted the night before - the preheating was done the following morning - engine started - warmed up and the required run time to boil off the fuel in the oil was completed. The aircraft took off - and the engine propeller gear reduction failed due to a lack of oil viscosity. This was due to the fact that the oil dilution valve was still in the on position - even though the switch was in the off position. Solenoid valves do stick open at times and in this case the fuel was flowing into the oil the entire time.. The pilot mentioned that he was going to snag the low fuel pressure after the flight. The low fuel pressure was the only indication you get under this condition. It was a 14 mile walk back to Baker Lake for everyone!!

I worked a Bell 47 contract one fall when the weather turned really cold. We had no heater for several days until the company could ship me one. We had electrical power and a small fan type heater - so we would finish the days flight and on shutdown I would be under the machine with a 5 gallon pail and drain the hot oil into it. The pail went into the cook-shack where it sat by the stove keeping warm for the night. My job upon getting up was to put the oil pail on the stove to heat up - go outside and check the machine - make sure the heater was working - and then after the pilot had completed his preflight and was ready for an engine start I would then dump the contents of the nice hot oil into the tank. Once gone - I would signal for him to start the engine - we only had one shot at it because if it didn't start on the first try - the spark plugs would be iced over. In that case I would have to drain the oil - back on the stove - pull all the plugs - dry and clean - re-install - and then attempt a start again. Once started we were good for the day - if it looked like an extended shutdown time for the day - then we would go and run it before it got too cold.

I DO NOT MISS THOSE DAYS!!!

Good article from Mike - but his focus is on the dinky toy airplanes.

Stay safe

Mx

[CFR]

I had a Reiff pre-heat system installed. Heater bands on each cylinder, a heater on the sump and one on the oil cooler. It is hooked to a cell phone switch. The airplane also has a nicely fitted insulated cover for the cowl. When I wake up and the weather seems good enough to fly, I text the airplane to turn on the heat and a few hours later it is toasty warm and ready to go.

[dave_091]

I had a Reiff pre-heat system installed. Heater bands on each cylinder, a heater on the sump and one on the oil cooler. It is hooked to a cell phone switch. The airplane also has a nicely fitted insulated cover for the cowl. When I wake up and the weather seems good enough to fly, I text the airplane to turn on the heat and a few hours later it is toasty warm and ready to go.

I'm envious of your setup!

This morning it was -17 and I keep my plane outside (I know it should be inside, waiting for hangar space to open up). I had to pull the plane with a towbar about 200 yards through ice and snow (it was a good pre-workout for leg day in the gym later) to the flying club. I put two heaters under the hood for an hour and a half until the engine was warm to touch. Then it was time to go flying, 3.5 hours after I left my house to go to the airport.

This was all after my standard hour and a quarter long drive to the airport.

I love flying... And aircraft ownership. It's the end of my first year of ownership and I would never go back to renting ( unless it's for ratings, etc).

[black hole]

A good rule of thumb: If temperature is at question; Pull the prop against the compression and release it. If the prop springs back, you should be good to go. If it doesn't: than it aint gonna start anyway.

BH

[CFR]

I had a Reiff pre-heat system installed. Heater bands on each cylinder, a heater on the sump and one on the oil cooler. It is hooked to a cell phone switch. The airplane also has a nicely fitted insulated cover for the cowl. When I wake up and the weather seems good enough to fly, I text the airplane to turn on the heat and a few hours later it is toasty warm and ready to go.

I'm envious of your setup!

This morning it was -17 and I keep my plane outside (I know it should be inside, waiting for hangar space to open up). I had to pull the plane with a towbar about 200 yards through ice and snow (it was a good pre-workout for leg day in the gym later) to the flying club. I put two heaters under the hood for an hour and a half until the engine was warm to touch. Then it was time to go flying, 3.5 hours after I left my house to go to the airport.

This was all after my standard hour and a quarter long drive to the airport.

I love flying... And aircraft ownership. It's the end of my first year of ownership and I would never go back to renting ( unless it's for ratings, etc).

I feel the same, and installing the Reiff heater makes it a little easier to face the cold weather.

[Airmanship Police]

I wouldn't pre-heat any engine for a good reason....


I would get the ramp rat to do it!!!

[Rookie50]

It was stupid cold today in southern Ontario with the wind chill. Cold and low level turbulance. Fine day for 3 short legs, but still happy I did them! And for my Reiff too.

[xsbank]

GA MX (etc) I enjoyed that. Thanks.