How cold is too cold to start

Discussion in 'Maintenance Bay' started by brien23, Feb 13, 2018.

  1. brien23

    brien23 Line Up and Wait

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    How cold is too cold to start a engine with 100 weight oil, 80 weight oil, multi weight oil at what point do you use preheat. How long do you use preheat like a heated air into the engine compartment below 40-F below 32-F below 20-F below 10F below 0-F.
     
  2. mscard88

    mscard88 Touchdown! Greaser!

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    Flight school's sit outside and they usually preheat them when it's below 40*, or I'll do it myself. Mobile unit, stick the hose into the cowling for 10 minutes. Planes crank right up.
     
    Last edited: Feb 13, 2018
  3. Clark1961

    Clark1961 Touchdown! Greaser!

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  4. Ryanb

    Ryanb Final Approach PoA Supporter

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    Anytime the temp goes below 40F ours get preheated.
     
  5. tinerj

    tinerj Cleared for Takeoff

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    If the overnight temperature is above 28 and the pull it out of the hangar for take off temperature is 45, then I start it without preheat.

    Once I start it, I like to see movement of the oil temperature hand before take off.
     
  6. Stewartb

    Stewartb En-Route

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    Lycoming and Continental both have published cold start service letters that discuss temperature minimums, preheat requirements, and oil types. Read the one that applies to your engine.
     
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  7. James331

    James331 Touchdown! Greaser!

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    it's 20F or below for continental


    [​IMG]
     
    Last edited: Feb 13, 2018
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  8. denverpilot

    denverpilot Taxi to Parking

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    What?! Pilots read the manual?!

    This is PoA! We’ll have none of THAT! :)
     
  9. frfly172

    frfly172 Touchdown! Greaser!

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    I pre heat below 40, anything below that ,my airplane is a real PITA to start,without preheat.like to get the oil above 50 when starting.
     
  10. swingwing

    swingwing Pre-takeoff checklist

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    I’ll turn on my preheater for at least 5 hour before I fly if temps are below 35 F. Sometimes I get into locations where preheating is not practical and I’ll start without, but I’ll never attempt it below 20F. I got a homemade campstove heater to use if temps are too low but it is a real PITA.
     
  11. azure

    azure Final Approach

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    I usually preheat below 50F. I use multiweight, Aeroshell 15W50.
     
  12. Stewartb

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    Hmm. I preheat per manufacturer's recommendations. If I preheated at 50* I'd preheat 9 months of the year!
     
  13. Checkout_my_Six

    Checkout_my_Six Final Approach

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    yup....and you also save in wear and tear. ;)
     
  14. NoHeat

    NoHeat En-Route PoA Supporter

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    Continental has only one letter that I can find, applicable to all engines. SIL 03-1 It says to preheat if cold-soaked below 20 F for 2+ hours, and it expresses some thoughts about how to start a non-preheated engine between 20 F and 40 F.
     
  15. azure

    azure Final Approach

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    Okay, let me qualify that: I don't preheat just because the overnight temp drops below 50F. Only if the ambient temp for most of the morning before planned departure is < 50F. I figure exposed metal will equilibrate to ambient fairly quickly, and then conduction will bring the cylinders to roughly the same temp. I rarely leave in the early morning anyway. That means no preheat needed for about 7-8 months out of the year. The other months, I fly much less anyway, so I'm not using the preheater *that* much.

    Though, I don't pay the electric bills here, and my hangar rent is the same regardless, so it's not really a factor for me.
     
  16. Norman

    Norman En-Route

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    Granted that while there are differences in engine construction would anyone buy a car with an engine that needed to be preheated? I think not.

    For the record, I have been in situations where I needed to cold start a plane. No damage resulted from doing that. When I had to do so I let the engine run at idle speed for a bit before applying power.
     
  17. Stewartb

    Stewartb En-Route

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    The bottom of the green for my engine oil temp is 70*. I don’t apply taxi power until I see that and it doesn’t take very long when the engine is started at 25* or so. In that time I’m waiting for the muffler to provide some defrost heat anyway since windows fog quickly in a cold plane with a warm human inside. I know lots of guys that use 32* as a preheat threshold. There’s no evidence that I’ve seen that supports that limit but it won’t hurt anything, either. My little Odyssey battery spins my big Continental to life easily down in the mid-20s but it takes lots of prime to do it. Below that temp? There’s a fine line between adequate prime and flooding. And THAT’s why I preheat.
     
  18. Checkout_my_Six

    Checkout_my_Six Final Approach

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    let me leave this right chair....note the differences between Aluminum and steel, major engine components in aircraft engines. :D [​IMG]
     
  19. Stewartb

    Stewartb En-Route

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    So for my engine that operates in the 400* range and starts in average temps around 50* and down to manufacturer’s published limits at 20*.... how much different are the engine tolerances at 20* and your preferred 40*? Since the manufacturer has done virtually all the engineering and testing, provides warranty, and accepts liability for their products... what do you offer that outweighs what they say? I don’t have a particular objection to anyone preheating. My question is why you think your practices are better? What evidence do you have. Not internet BS smoke and mirrors, but real evidence?
     
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  20. Checkout_my_Six

    Checkout_my_Six Final Approach

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    that's engineering data my friend.... ;)
     
  21. Stewartb

    Stewartb En-Route

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    It’s a table of values. How does it apply to my specific question?
     
  22. Checkout_my_Six

    Checkout_my_Six Final Approach

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    well....what are these parts made from? ...and what temps are the parts designed to? What about the extremes?....what about the tolerance stackup?
     

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  23. GMascelli

    GMascelli En-Route

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    45 and below I’m sending a text to the hangar switchbox and turning on the preheats, oil and cylinders. During the winter months I always plug in and cover cowl and prop with moving blankets.
     
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  24. Stewartb

    Stewartb En-Route

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    More smoke and mirrors. Never a straight answer.
     
  25. MauleSkinner

    MauleSkinner En-Route

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    If you'd calculate your density altitude, the answer would be obvious! ;)
     
  26. Fearless Tower

    Fearless Tower Touchdown! Greaser!

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    Out of curiosity, is that published, or just a personal presence. All of my airplanes will taxi at less than 1000 rpm. My Beech 18 has published min temp for runup and min temp for takeoff and flight but I’ve never seen a minimum taxi temp.
     
  27. James331

    James331 Touchdown! Greaser!

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    You're cruising at 400f CHT? Do you have louvers or anything?

    Normally I lean and cowl flap for 380 climb and 350 cruise
     
  28. Stewartb

    Stewartb En-Route

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    Whether on tires or wheel skis it takes generous application of throttle to move my plane out of the gravel tie down and along the gravel and sand taxi area. Maybe more important is that my average taxi length is about 600', so there's not much warming to do during taxi. My Cessna oil temp green range starts at 70*. My SAP IO-400 low green is 75*. I usually want to see 275* CHT before pulling out of parking and with that oil and cylinder temps are good to go at about the same time.
     
  29. flyingbrit

    flyingbrit Filing Flight Plan

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  30. Norman

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  31. Tarheelpilot

    Tarheelpilot Pattern Altitude PoA Supporter

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    So, just to be clear you don’t think the engine manufacturers considered dissimilar metals and clearances inside the engine when they made recommendations for cold weather operations and you know enough about said clearances and engine design work that you are willing to throw your engineering around to justify a warmer temp than the manufacturer recommended.

    If you said you like preheating at a warmer temp than manufacturer recommends because you are a conservative owner and you want to do everything possible to ensure long engine life then I would agree with you. But to imply that others are hurting their engines by following guidance from the manufacturer is a bit of a stretch. You haven’t presented enough information to corroborate your statements.
     
  32. Tarheelpilot

    Tarheelpilot Pattern Altitude PoA Supporter

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    My truck has to be plugged in during my winter months. Doesn’t bother me in the slightest.
     
  33. gkainz

    gkainz Final Approach PoA Supporter

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    my truck doesn't have to be plugged in during my winter months, but it makes it nice to have heat in the cab much quicker when it is.
    It does start much quicker when plugged in...I usually plug in if temps go below 0F.

    Oh, and just to keep it aviation-related, our club policy is to plug in our planes while hangared when temps are 40F or below.
     
    Last edited: Feb 14, 2018
  34. Tarheelpilot

    Tarheelpilot Pattern Altitude PoA Supporter

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    That thread wasn’t the same situation. Inaccurate reference.
     
  35. Stewartb

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    I can count my truck plug-in days for the past 25 year on one hand. Starting those at -40*F is without heat is simple, even with diesels. At -45* for a few days the diesels get too stiff but the gas motors fire right up. I recall the Duramax manual saying to plug in below -30*. Most of the time there isn't a power outlet available so we do without. My trucks use 5-30 synthetic oil and my other 4-cycle equipment uses 0-30. But that has little to do with starting an air cooled airplane engine.
     
    Last edited: Feb 14, 2018
  36. Checkout_my_Six

    Checkout_my_Six Final Approach

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    yup.....I'd avocate warmer startups are less wear and more better for all the moving parts.

    A good friend of mine was a Lycoming engineer and for grins did a stackup analysis of an old design and discovered a few things. Those "things" never made it to the marketing glossy documents. The first was the "possibility", a remote one but, none the less, possibility of spinning a main bearing due to a cold thermal interference. The parts have to be mixed and matched just right on a "new" engine....but mathematically he was able to have metal to metal contact on the front main journal bearing....enough for it to spin ....at temps around 32 F. An older engine, one with wear, wouldn't have this issue. Another discovery was the possibility of a thermal induced line-to-line or metal contact in the choke area of the cylinder with the piston & rings. All due to differences in thermal expansion or coefficient of thermal expansion between steel and aluminum parts.

    The second observation is well known and the evidence can be observed when tearing down tired cylinders....
     
  37. Tarheelpilot

    Tarheelpilot Pattern Altitude PoA Supporter

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    Which “old design” did he do the stack up analysis on?
     
  38. Checkout_my_Six

    Checkout_my_Six Final Approach

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    IO-540.....but, they all are very similar in the stackup.

    We aren't seeing airplanes fall out of the sky because of cold starts.....IMHO it just makes good practice to pre-heat....and I choose 40 deg F as my comfort or safety factor.
     
  39. Fearless Tower

    Fearless Tower Touchdown! Greaser!

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    That makes sense. I’m based on pavement, so taxiing is a little different for me. I usually end up getting to the runup area and waiting for the several gallons of oil to come up to temp.
     
  40. James331

    James331 Touchdown! Greaser!

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    I might talk to who ever made that policy if I were you, I don't think any of the engine manufactures recommend that, and making things up as you go isn't a good idea.