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Thread: Low oil temp on J-3

  1. #1
    55-PA18A's Avatar
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    Low oil temp on J-3

    A friend with an 85 hp J-3 and I were discussing oil temps during fall/winter flying. He mentioned he consistently gets 110 degrees above ambient air temperature. That's OK during warm weather, but when it's cool he would like to get his oil temp up to burn off moisture in the oil. He puts an insulated cover over his oil sump, but would be interested in what others with open-cowled aircraft do to increase oil temp.

    Jim
    Last edited by 55-PA18A; 10-24-2021 at 02:01 PM.

  2. #2
    Crash, Jr.'s Avatar
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    I've put the Wag Aero oil sump blanket and intake runner covers on mine as well as taped over the little "mouth" in the front of the cowling that blows cooling air on the sump. Still only get 140 degrees max this time of year and 160 in the summer. Sorry, can't be of much help as I'm in the same boat.
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  3. #3
    Richgj3's Avatar
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    I had a Legend Cub. 100 HP O-200. I got 110 over ambient all year round. My buddy had a Legend. Just like mine we used to fly together and get the same oil temp. In the winter I put the oil tank blanket on and covered the hole with a metal plate. He didn’t. We still got the same oil temps in the winter.

    100-110 over ambient is all you can expect. IMHO.

    I now own a C170B with the C145 motor. Same cylinders as the O-200. No oil cooler. 110 over ambient. Blocking the hole in the cowl that blows on the case gets maybe 10 to 15 degrees more in the winter.

    Rich
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    cubdriver2's Avatar
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    My 11 had over 400 hrs of ski time and most days it never got to 110F. I put 2200hrs on it and ran fine right up till I wrecked it. Don't worry about it

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  5. #5
    BC12D-4-85's Avatar
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    Anyone remove the cylinder eyebrows in winter and test engine temps?

    Gary

  6. #6
    mvivion's Avatar
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    Quote Originally Posted by Crash, Jr. View Post
    I've put the Wag Aero oil sump blanket and intake runner covers on mine as well as taped over the little "mouth" in the front of the cowling that blows cooling air on the sump. Still only get 140 degrees max this time of year and 160 in the summer. Sorry, can't be of much help as I'm in the same boat.
    I did the same on my PA-11, with a C-90. Same results, but I never flew in colder than zero F. Never saw an issue that concerned me.

    Just go fly. These little engines been flying around in winter for decades, and seem to have done okay.

    MTV
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  7. #7
    skywagon8a's Avatar
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    Quote Originally Posted by BC12D-4-85 View Post
    Anyone remove the cylinder eyebrows in winter and test engine temps?

    Gary
    Not a good suggestion as the eyebrows are used to turn the airflow down so all the cylinders get the same air. Unless you install a sophisticated temperature probe system measuring barrel and base temps, leave it well enough alone.
    N1PA
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    Crash, Jr.'s Avatar
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    I have a picture somewhere of a "winter kit" that someone did where they added a couple plates in front of the eyebrows with about 1" holes to let less air through.

    Here's one thing I've been wrestling with is the difference between CHT and oil temp. Of course they have a relationship but I don't think blocking off cylinder cooling flow is going to raise oil temp all that much and might cause issues with burning valves. My brother's A65 burnt a valve on the #3 cylinder recently and had done it before in the logbooks. That engine does 80-100 degrees above ambient on the oil temp all the time. My theory is that the CHT's are probably fairly high on these small continentals because they're run so hard but the CHT isn't monitored and all you get is feedback from the oil temp which is low in comparison to Lycomings so there's a disconnect there that they need to be leaned and have cooling air blocked off to get temps up. Just my theory and I'd like to hear from someone that's had a CHT on a small continental as to how the CHT and oil temp relate to each other.
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    mvivion's Avatar
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    The thing I worry about with covering or blocking part of the cylinder flow is turbulent air, as well as lack of flow. Too easy to develop hot spots on a cylinder, as well as potential valve train issues.

    MTV
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  10. #10
    Crash, Jr.'s Avatar
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    Click image for larger version. 

Name:	cyl baffle1.JPG 
Views:	30 
Size:	51.2 KB 
ID:	58107

    Here's the picture I was referring to. I agree with MTV, definitely the potential for causing more issues than they solve.
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  11. #11
    BC12D-4-85's Avatar
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    Without a multi-probe CHT/EGT the effects of cold dense air on air-fuel mixtures is another concern. My PA-11 with that setup would run near an EGT peak on #2 at -20F. Carb heat helped lower the exhaust temps. They are not a cold weather engine compared to a Lyc. I always had water condensed inside the oil filler after a winter flight.

    Edit: Logged data showed indicated oil temps ranged from 160F at -20 to 180F around 0F in that PA-11-90. Cowl hole below prop closed. ~2350 rpm.

    Gary
    Last edited by BC12D-4-85; 10-25-2021 at 02:01 PM.

  12. #12

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    Fly more often and use Camguard in your oil. Mine only got up to 160 today, flew with my door open, such a nice day, I’m not worried.

  13. #13
    Crash, Jr.'s Avatar
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    Any thoughts on changing from 20W50 phillips to something like Aeroshell 80 plus for the winter? Think that would help the oil temps?

  14. #14

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    im kind of a nerd for getting all the water out of all of my engines oil. and tried a few things on c85's, c90s and 0200's. ive invested my entire life into my cub and want to do eveything i can to make it (particularly is extremely expensive motor) to last my lifetime (or to make TBO and beyond).

    for winter on a stock style J-3 exhaust if i remember right.
    1. wrapping the oil sump raises oil 10-30 degrees depending on material and its airtightness
    2. running the oil topped off seemed to get the temps up, i think its because theirs less ratio of oil splashing down the oil tank which is acting like a big heat sink.
    3. clamp a peice of sheet metal to the carb heat intake to act as a ghetto air-scoop. (the stock front air intake on J3's doesnt flow air worth beans). T into the carb heat scat tube and attach that to your oil tank wrap in a way that it blows hot ram air on the oil tank when carb heat is off. (i beleive i had routed this additional line in a way that it also supplemented my cabin heat but it been a while since i looked at that plane and might be wrong about that memory.)

    if i remember right those mods got the 85 hp J3 i was flying oil temp from 110-120F up to 180ish on a 30 degree day.
    anytime i found water on the dipstick, on the next flight i'd do a 40mph full throttle turning/slipping climb and get the oil temp up to 210 and that would burn off the water.

    other tips.
    1. make every flight at least 1 hr in the winter. a 30 minutue flight even in the summer with my 0200 makes tons of water. (if your dipstick is full of cottage cheese, so are you valve covers and accessory case)
    2. dont use mutli-viscs in low comp continentals, particularly when running leaded fuel.
    3. stick with w80 or w100 with some cam guard or fly your plane often. theirs some very eye opening and confirming resaons for that savvy avation put on youtube called "all about oil' that is very well worth the watch.
    4. dont cover your inner cylinder baffels. i only see potential problems doing that.
    5. my preheater is a $5 hair drier blowing directly on the oil sump. 30 minutes gets me from 32f to 120F on my temp gauge and 1 hr gets the entire engine to 140+. the result is that my oil temp gets up to 180 WAY WAY quicker making the water start to burn off sooner.
    6. i distrust and dislike the glue on oil sump heaters for many reasons. 1. they create cold spots in the motor and those cold spots act as water condensers. 2. they are dangerous as hell, we found many sump heaters that where peeling off which was causing dangerous overheating (as in smoke in the hamger), and failing wiring that was 1 gas fume away from burning up a plane and hanger 3. they dont warm the cylinders worth beans compared to a hot airbath and 4. they take forever.


    additional brainstorm i just had.
    how about building some baffels that route the hot inner cylinder air down onto the oil sump?

    and of course we'd NEVER EVER do any of these mods to a certified aircraft because that would be extremly dangerous and highly illegal, these mods are only safe if its an experiment.


    theirs a couple tricks for lowering small continental oil temp too, but i'll leave that for the summer.
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  15. #15
    cubdriver2's Avatar
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    I don't worry about it. If you reach that magic 180f at sometime during the flight and boil off all the moisture ( doubtfull) you will still be making water again below that temp while defending back down and taxiing back to the hangar.

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  16. #16
    BC12D-4-85's Avatar
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    After flying remove the oil dipstick to let the water in the sump escape some. You can see steam rising out when cold. Put the oil stick on the pilot seat so don't forget it's removed.

    Gary
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