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Thread: Coldest Cub--Why?

  1. #1
    mvivion's Avatar
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    Coldest Cub--Why?

    Okay, you mechanical wizards out there in Supercub.org-land, here's a puzzle for you:

    A, shall we say, Brand X model 18, 180 hp, practically new airplane. Minnesota mornings, and afternoons, for that matter. Let's say anywhere from -20 all the way up to +5. Fahrenheit, okay?? I don't do Celsius.

    The oil cooler is on the aft baffle. Completely covered with, er, a covering substance that comes in rolls.

    Absolutely no trace of cabin heat. Maximum OIL temperature in these temps is to date 94 degrees F. MAXIMUM!!

    CHT's running around 200.

    There is no defroster, and it is nearly impossible to keep the windows defrosted.

    There is no forward heat muff on the forward crossover tube of the exhaust, so that's some of the lack of cabin heat.

    What I can't understand is why this thing never gets above human body temperature, OIL-wise.

    Any thoughts would be appreciated.

    MTV

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    heat

    Hello MVivion. I don't know the answer to your oil problem, but yesterday at -20C (-5F) with my 160 with Leading Edge Exhaust and F. Atlee Dodge rear seat heat installed, no defrost kit yet my passenger and I were comfortable and I actually was only using intermittent heat. I had it plugged in overnight with the Reiff pads and bands and a good fitting(modified) Articovers engine blanket, spinner and blade covers. We had 114 degrees oil temp showing at start up and when the oil from the sump got up to the temp sender it was 124 degrees. the front mounted oil cooler was covered with something on a roll completely and the oil temp rose to about 165 degrees not working hard. I have flown this airplane at -38C and the heat on my heels is plenty hot. I usually just run the rear seat heat flying solo. I have the Vernatherm oil thermostat on the engine. Do you know if you have it? Some of the Lycoming experts can probably explain how it works and if it is a benefit for cold weather. I just wish I could seal up the window weatherstrip a bit better to keep the draft down for the passengers top half. Our CHT is always 300-325 in the cold after climb out. Hope you find your answer.

  3. #3
    Steve Pierce's Avatar
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    Is the vernitherm working? At those temps the oil should not even go to the cooler. Where is your blast air coming from for cabin heat. SJ has the Sutton exhaust and when everyone was down here I heard someone ask him about his heater. He said it worked great.
    Steve Pierce

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    Will Rogers

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    Erik's Avatar
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    Mike,

    Is this a new problem or has it always been like this?

    Do you have a defroster at all, or is it just not putting out heat?

    I have a year 2001 Cub Crafters 180 HP conversion on my Cub, so I assume it is similar to what you have. I have the aft oil cooler 100% blocked off with an aluminum plate, and I have a defroster installed. At 0F, I can get about 160F oil temp and good cabin/defroster heating action. I don't see why you would be any different.

    Erik

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    mvivion's Avatar
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    Steve,

    I'm suspicious of the Vernatherm. Is there any easy way of telling if it's sticking open?

    There is NO defroster installed. This is a new airplane, thus a new problem.

    The cowling on these things is so wide open, I'm not surprised it runs cold, but this is ridiculous.

    C-FVUA--Yep, I've run a lot of Cubs with the Atlee heat kits. Part of the problem with this one is there's no forward muff, so you aren't getting pre-heat.

    The intake on this thing is 90 degrees to the airflow up on the front baffle. Doesn't make any sense to me, though it may have been done that way for ice protection.

    We are going to install a defroster soon, but all that does is takes ALL cabin heat and puts it on the windshield. Actually, since there's hardly any cabin heat, I'm not sure what it'll do.

    I really hope this is something simple like a stuck vernatherm.

    They put the lightweight Tanis system on this thing and a worn out Tanis engine cover, so the engine never gets warm overnight either. That is the owner's fault.

    Keep the ideas coming, folks.

    MTV

  6. #6
    Widebody's Avatar
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    Mike, I'd have Lowell M. right there or Randy R. close by take a look at it.
    You've got two of the best close by. My CHT runs up to 250 at idle and 350 in flight at -20f and about 165 oil temp with oil cooler blocked off on left rear baffle, your air pickup should come from the bottom cowling for the front and when you install rearseat, the right rear baffle. I have L.E. Exh. and all the heat from the muff goes directly to the cabin, front and rear. I rob carb heat from the stack. I close off the baggage area behind the rear seat when it's cold with a blanket and the other day when it was -10f myself and biologist had coats off with just a t-shirt/flannel on and were very comfortable. Couldn't resist telling you how warm we were . You've definitely got problems somewhere .

    Brad

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    mvivion's Avatar
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    Brad,

    Yeah, I've been discussing with Lowell. UND airplane, and they don't fix things that aren't broke. Cold CFI ain't "broke", so trying to find a simple solution.

    I don't think the heat system in this airplane in stock configuration CAN make much heat, but this engine should run warmer.

    These guys are so cheap they won't buy an engine cover that completely closes up the cowl. Duh. So the engine starts the day cold.

    Thanks for the "warm" message . I'm about to go get froze out again.

    MTV

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    Steve Pierce's Avatar
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    Vernitherm should be open to allow the oil to bypass the cooler. Best way is to remove the vernitherm and heat some oil and see how much it extends at what temp. Don't remember the spec but Lycoming could tell you. You could remove the snap ring which allows you to take the vernitherm part out of the plug, reinstall it and then install the old fashioned ball and spring in the other hole on top of the accessory case by the crankcase vent. The ball and spring requires the oil to get hot and thin before it unseats the ball and allows the oil to run through the cooler.

    I think I will stay here in Texas where 30 degrees is cold.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  9. #9
    mvivion's Avatar
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    Minus 18 F at start. Very petite and tough young lady in the front seat. She's doing well despite being frozen. Her landings are polishing up nice. Near to solo time.

    I'll be cold till 4 this afternoon.

    MTV

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    Are the inter-connect baffles in place/missing?

    Dennis

  11. #11
    mvivion's Avatar
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    Yep, the intercylinder baffling is in place.

    MTV

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    SJ's Avatar
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    Mike,

    Crazy idea, but what about calling the manufacturer of the airplane?

    sj
    "Often Mistaken, but Never in Doubt"
    ------------------------------------------

  13. #13
    mvivion's Avatar
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    Mechanic did that.

    MTV

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    55-PA18A's Avatar
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    Geesh,...what's this? A guy moves down south and then thinks he's got to have heat in a Cub.

    Jim

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    mvivion's Avatar
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    Crookston has been consistently colder than Fairbanks the last couple weeks.

    And, that doesnt count wind chill, either, which has been substantial as well.

    Call me a wimp .

    A cold wimp. -18 at the moment, and fixing to go do an hour and a half more.

    MTV

  16. #16
    Dano Bardwell's Avatar
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    cold cub

    Mike have you checked to see if your temp gauge/prob are reading right?

  17. #17
    Erik's Avatar
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    Quote Originally Posted by mvivion
    I don't think the heat system in this airplane in stock configuration CAN make much heat, but this engine should run warmer
    But Mike - I just told you my engine and yours are similar and mine DOES make heat. So why doesn't yours then???

    I like Cubskull's idea concerning the possibility of a inaccurate temp gauge/probe. But that doesn't account for you not getting heat in the cabin. Are you sure you're getting airflow through your cabin heat system (muffler shroud into the cabin)?

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    Hello Mike.

    I don't think you're a wimp. Anyone can live nearer the equator, you have to be tougher and smarter to brave the colder climates....... Or that is what I tell people who suggest otherwise. The Darwin theory of evolution comes to mind as well. Hopefully you get it sorted out. Nobody will be able to call you a heater hugger anyway. Cold weather tends to cut down on riff raff!!!

  19. #19
    Cubus Maximus's Avatar
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    After 3 week of this, lots of people around here are beginning to think the riff raff know something we don't...

  20. #20
    Snert's Avatar
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    Cold vs. COLD
    60 above zero:
    Floridians turn on the heat.
    People in Minnesota plant gardens.
    50 above zero:
    Californians shiver uncontrollably.
    People in Duluth sunbathe.
    40 above zero:
    Italian & European cars won't start.
    People in Minnesota drive with the windows down.
    32 above zero:
    Distilled water freezes.
    The water in Lake Superior gets thicker.
    20 above zero:
    Floridians don coats, thermal underwear, gloves, wool hats.
    People in Minnesota throw on a flannel shirt.
    15 above zero:
    New York landlords finally turn up the heat.
    People in Minnesota have the last cookout before it gets cold.
    Zero:
    People in Miami all die.
    Minnesota people close the windows.
    10 below zero:
    Californians fly away to Mexico
    People in Minnesota get out their winter coats.
    25 below zero:
    Hollywood disintegrates.
    The Girl Scouts in Minnesota are selling cookies door to door.
    40 below zero:
    Washington DC runs out of hot air.
    People in Minnesota let the dogs sleep indoors.
    100 below zero:
    Santa Claus abandons the North Pole.
    Minnesota people get upset because they can't start the Mini-Van.
    460 below zero:
    ALL atomic motion stops (absolute zero on the Kelvin scale.)
    People in Minnesota start saying..."Cold 'nuff fer ya?"
    500 below zero:
    Hell freezes over.
    MINNESOTA public schools will open 2 hours late.

  21. #21

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    Too much air plus other little problems. I would first confirm that the oil temp prob is correct. This can be done by heating up a can of oil with a digital oil temp and the prob measuring the same fluid. Next I would check the plumbing for correctness.
    The verna therm won't need testing for cycling. In this case upon inspection it should appear to be closed tight thus diverting all oil to the cooler all the time. The pressure relief spring spring is either high or low oil pressure. The induction system also cools the oil and nothing to do there. A fully closed vern is most likely the prob. I also would run thin oil for the temps. Duct tape the cowl openings a little more each time until you get the operating temps. If your problem isn't corrected, that engine wont last very long running at 94 degrees, but I'll but you already know that. I have a friend that has closed down his very similar cowl openings by 35% thus reducing cooling drag. He runs fine on summer days. I plan experimenting with this to see if there is speed to be obtained by reducing cooling drag.

  22. #22
    mvivion's Avatar
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    Thanks for all the ideas, guys. I'm waiting for the 100 hour to get into it. If we can keep it flying during the cold to GET TO the 100 hour, that is. Otherwise, it may be a moot point, and next years problem. 9 to go. The owners don't do out of cycle maintenance unless something is actually broken, so getting an authorization from them to "scout" is tough. Besides, they sit in a warm office, so....

    Smart mechanic here, so we'll come up with something. Fortysix--I agree the cowling is WAAAAAYYyy too wide open on these things for these temps. For glider towing in Phoenix, it would be perfect, though.

    I've never taped over cowl inlets. Takes off paint, and really attracts attention from unwanted corners. Most inspectors won't get deep enough to see a little tape on the oil cooler, but putting it out front is asking for it. Also, air flow does weird stuff, and I'd be really reluctant to get too wild and crazy out front like that. My old Cub, I built block off plates of aluminum that screwed to the firewall with rivnuts in the firewall. These blocked off the cheek cowl openings, and really helped moderate and organize engine temps. These cheek openings are HUGE on this, but again, getting permission would be out of the question, without an STC.

    ANyway, thanks for the ideas, and we'll see what we see.

    MTV

  23. #23

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    Wasn't implying to fly around with duck tape, just experiment out of site to see what can be obtained. If this CC has the composite cowl, it probably is more even more efficient than the my factory.

  24. #24

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    You might want to check how much airflow is going through the heat ducts in flight, tie a piece of cloth to the outlet to have a visual. too much airflow will not heat the air, no airflow shows blockage.

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