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Thread: New (to me) Supercub... Running hot? Charging issues too

  1. #1

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    New (to me) Supercub... Running hot? Charging issues too

    o-320 160HP.

    Flew it around today. It's 40 F outside.

    Short climbs of just a thousand feet or so are showing 460 on the CHT for number 3. Other cylinders are in the low 400s.
    A longer climb, slow airspeed.. showed CHT on number 3 of 490.

    Cub is a widebody BCSC. Only 40 hours on the motor.

    EGTs told a similar tale. 1400s on the others.. and number 3 near 1600.

    Have another head scratcher on the voltage display. Seems it's charging. Voltage shows 15+ Plane started ok when cold. I took it around the patch twice. Got back in it didn't start. I propped it.

    As I fly around.. sometimes it seems voltage is at 15+.. others it's down under 12.

    Appreciate the help.

    JP

  2. #2
    n40ff's Avatar
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    I never see EGT's that high....?

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    That is way too hot. What RPM's are you climbing at? Recheck the timing and the intake for leaks. What is your read up on proper baffling. How big are your cheeks? Do you have a seaplane lip? What rpm drop do you get when you pull carb heat (should be around 100 -125). Any carb mods?
    DENNY

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    wireweinie's Avatar
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    Yes, 15 volts is to high. This will cause battery problems. 14.2 volts is ideal. +/- about .2 is still okay. More than that, it should be addressed. 12 volts or less in flight means you're not charging (that's just the battery). What charging system is this and how much time since installed? Has it ever worked correctly?

    Web
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    Many questions I don't know all the answers to.

    I'm not asserting the EGT number is correct, but just going off the fact that #3 is 15% higher than the others.
    RPM climbing out is a couple hundred under redline.. So from memory that's 2400 ish.

    I THINK the seaplane lip is on there. Lip on the bottom of the cowl for low pressure is maybe 3 inches??

    No idea on charging system. I just bought it. I would agree at some times I was on battery only. The times did not coincide with power at idle or anything. IF I had to guess.. I'd say the battery ran down to something like 11.5.... then charging system was off to the races again at 15+ . This cycle repeated a couple of times.

    Thanks
    Jason

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    oh

    I believe there was no drop at all with application of carb heat.

    JP

  7. #7
    wireweinie's Avatar
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    Quote Originally Posted by JP11 View Post

    No idea on charging system. I just bought it. I would agree at some times I was on battery only. The times did not coincide with power at idle or anything. IF I had to guess.. I'd say the battery ran down to something like 11.5.... then charging system was off to the races again at 15+ . This cycle repeated a couple of times.

    Thanks
    Jason
    Just with the info you've shared; IF the system was wired correctly, there are problems with the regulator. Otherwise, I'm extremely suspicious of the wire connections. Give me a brand and model of charging system and I can give you better troubleshooting ideas.

    Web
    Life's tough . . . wear a cup.

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    When you lean the engine in cruise can you get 150-200 degree rise in egt before the engine starts to run ruff? what type of mags? emag? check your baffling for leaks along with your intake. the higher comp pistons can make an engine run hot but your #'s on a 40f day are really high, hows your oil temp? Is the engine burning oil?

  9. #9

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    I didn't lean at cruise.. but I did see maybe a 50rise in a test on the ground.

    not emags
    I do need to check the baffling.
    oil temps stayed good. I don't think I saw anything over 180.
    Haven't put enough hours on it to say I'm burning oil. I've only flown it twice now, and not any more than a half hour. I've only owned it for a day.

    I'll see if I can get some info on the charging setup... and a brand name off the mags.

    Thanks. I knew the knowledge was here. I think I got a pretty good deal on the plane... but I knew there would be a 'cost' to shaking the bugs out. It's 8 years old.. with just 40.1 hours on it as of today

    JP

  10. #10
    behindpropellers's Avatar
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    Need more details.

    What kind of engine?

    Did they set the ring gap correctly? Who built the engine?

    What kind of instruments are giving you this reading?

  11. #11

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    hmm, 40 hrs in 8 yrs is not good these engines don't like to sit. Was it properly preserved? You should check your EGT rise in cruise, idling on the ground is not the same. As for EGT#'s they don't mean much because depending on the placement of the probes in the pipe it will effect the reading, but use them for a base line to run the proper LOP or ROP setting. If you can't get at least a 150 degree rise you could have an intake leak or need to have the carb looked at. What model 0320 is it?

  12. #12
    behindpropellers's Avatar
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    Is this the one that Larry Mayer was selling in MT?

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    It's a wide deck o-320 . (-27A)

    Overhaul Dick Waters in Florida it looks like Air-Tec

    it took two years and 4 months to get 25.5 hours on it.
    10 hours the next 4 years.

    Couple hours a year the past two years it seems.

    As for the instruments.. simple analog gauge for CHT and EGT.. with a small knob to cycle through sensors 1 thru 4 on each.

    I'll see what kind of rise I can get at cruise tomorrow. I stick by the thought that even warmed up.. the carb heat didn't seem to do anything.

    JP
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  14. #14

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    Quote Originally Posted by behindpropellers View Post
    Is this the one that Larry Mayer was selling in MT?
    No. East Coast. Was right at my home airport.. Twitchell's

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    Do you have high compression pistons? Sounds like you are running lean or have intake leak. When you climb you want the RPM to be 2600 RPM or higher. That will allow the carb economizer to add more fuel and help with cooling. If you could post some pics of the plane and items mentioned that would help. If a pepperbox jet was used when the motor was built it has to be drilled out quite a bit for proper flow on a 160. If you can talk to whoever built the carb that would help. If you have slick mags, they are notorious for having low time problems (internal timing)!! Where do you live?
    DENNY

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    aktango58's Avatar
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    There was lots of discussion previously on what I thought was a BCSC having cooling problems and what they changed to make it work. Ted Waltman had a lot of insight on that.

    A couple of things come to mind really quickly- first, climb out on full power. Using full power will actually get you more fuel into the engine for cooling.

    Next- as said before, probes can read differently or be installed differently, so best to watch for changes on the monitors.

    Carb cleaner sprayed on the intakes (especially at joints) with the engine running will quickly tell you if you have a leak; look for fuel stains prior to that though.
    I don't know where you've been me lad, but I see you won first Prize!
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    Thanks

    I'll work on this. Climbing at full power (I've got a lot of glider tow experience, so managing temps is nothing new)

    I'm going over there today. I'll get to the bottom of the issues... eventually.

    Thanks.
    JP

  18. #18
    skywagon8a's Avatar
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    Quote Originally Posted by JP11 View Post
    As for the instruments.. simple analog gauge for CHT and EGT.. with a small knob to cycle through sensors 1 thru 4 on each.
    Are these instruments electrically powered or self powered? If electrically, the trouble may have something to do with the generator not working. If not put the CHT probes in boiling water to find out if they are accurate. 400 is too hot for this time of year.

    What is your mag drop on run up? If high there could be a timing issue. There is also the chance that the rings never seated. Have you looked inside the cylinders for rust?
    Last edited by skywagon8a; 12-04-2018 at 07:27 AM.
    N1PA

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    I put the all the CHT probes in a can of oil at the same time, heat the oil to 400-450 and watch gauges.

  20. #20
    TurboBeaver's Avatar
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    Jason,
    Your carb heat sounds like mine......... Thanks Denny for posting the 100/125 numbers. Those sound spot on. There is a general trend with Cub airboxes for folks to accept 20/50 rpms nowadays. They all say " I never had a problem" . I had a personal friend destroy a total rebuilt beautiful 18 because of a bad case of ice his micky mouse airbox and routing couldnt handle! Could have easily cost him his life. If those cly readings are correct you
    likely have an issue? What does Dale Twitchell think. They
    have been though this for 60 years????

  21. #21
    stewartb's Avatar
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    The first thing I'd check is to make certain the rear baffle has a standoff at #3 to allow airflow through the cylinder fins.
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  22. #22

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    A few answers.

    Found a few leaves down under #3 Cylinder. Cleaned those out.
    Fixed a few very small issues with baffling.
    Found an intake leak on number 2.

    I believe it's running lean, as leaning it out at cruise yielded NO real increase in RPM.
    Short flights today.. never saw oil above 150...

    CHTs were better, and more balanced. Still up on 3 a bit close to 450.

    with wind blowing 20.. it was a handful, and jumped off the ground in about a hundred feet.

    Mechanic is going to fix the intake, and we'll work through the issues.

    I'm suspect of the gauges in general. I saw CHTs very quickly into the 300s at idle, and EGT of 1400 at idle. The gauges are self powered, as they did not move when I turned the master off.

    Battery is 8 years old.. and not really holding a charge. I had to hand prop it, even after going flying for 10 minutes, and it showing charging the whole time.

    Thanks.
    JP

  23. #23
    aktango58's Avatar
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    Make adjustments one at a time, otherwise you will not be able to identify where the improvement comes from...
    I don't know where you've been me lad, but I see you won first Prize!
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    I would bet the gauges/probes are fine, but, I would do test as noted above on them. What prop are you running? What type of baffling material do you have silicone or felt?
    DENNY

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    when i put the H pistons in my 0320 i had to up the jet size in the carb but can't remember to what size i drilled it out(that was 10yrs ago) so you may want to check, could be one of a few issues.

  26. #26
    tedwaltman1's Avatar
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    What does your cowl look like? Intake area? Outlets? Std cub style cheeks at sides or very tightly cowled? If you don't have sufficient airflow in/out you won't ever get proper cooling.
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  27. #27
    www.SkupTech.com mike mcs repair's Avatar
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    Bad intermittent ground between alternator and airframe/battery

    Maybe bad cell in battery regarding the 15 volts(alternator is trying really hard to get the battery charged, but can’t then) what type battery?

    Intake leak, look for the gasket at cylinder to be half blown out Or hose clamp loose. Also check intake tube coming out of sump is solidly attached


    Sent from my iPhone using SuperCub.Org

  28. #28
    stewartb's Avatar
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    Borderline lean will show up in cool temps. If the engine gets hot from first climb it's very difficult to get it back into normal range after. Adequate fuel flow is critical. Maybe it's time to ream the jet.

    #3 being hottest warrants checking air clearance aft of #3.

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    Dale Twitchell is on the case. I'm headed back to work tomorrow. Prop is a 74DM54 Sensenich. I saw just 2600 on climbout around 45 to 50kts

    He said we'd tackle this intake leak before messing with anything else.

    It seems like I'm not the first to mess with these type issues. I'll work through trying to learn from others.

    Thanks
    Jason

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    Battery's an Oddysey PC680. Got a new one coming.. that one is 8 years old. Then we'll see what it does. Dale said it always showed just under 15 volts.

    JP

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    stewartb's Avatar
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    Re: baffles. Here's an older thread with some info to consider. http://www.supercub.org/forum/showth...19-My-SQ2-Mods
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  32. #32
    nanook's Avatar
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    Mount a GoPro in there and see what your baffle seals are doing in-flight. Air is supposed to go down-around-through cylinder fins. When your baffle seals aren't working, goes straight out the back...
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  33. #33

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    The PC680 manual warns against going over 15.0v, most AGM's chemistry can't take it. I put a sticker on my typical 2/10/50 amp charger: no agm's!
    What's a go-around?

  34. #34
    wireweinie's Avatar
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    Quote Originally Posted by Skywalker View Post
    The PC680 manual warns against going over 15.0v, most AGM's chemistry can't take it. I put a sticker on my typical 2/10/50 amp charger: no agm's!
    Automotive type chargers are constant voltage chargers. That means that the voltage will remain at a set point, usually 14.2 to 14.5 volts. Only the charge current is regulated. If you have worked with nicad batteries, that charger is a constant current type. The output can be set to a desired level and the voltage will rise or fall in order to keep that level of current moving.

    I have a limit of five amps on most non lead/acid batteries, but that is simply due observations over the years, not any rocket science. With ANY battery of ANY type, a slower charge rate over a longer period of time is better for the health and longevity of the battery. A high charge rate (more amps) will cause the battery to heat up and can cause internal damage. Think 'one amp overnight' instead of '15 amps for an hour'.

    Nothing wrong if you don't want to use that charger on your AGM batteries, but it's an unnecessary precaution. If you set it on the 2 amp setting, you'll prevent heat damage to your batteries.

    Web
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  35. #35
    stewartb's Avatar
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    If you ever truly kill an Odyssey overvolt charging can tickle it back to life, but you need to sit there and monitor it. A liitle too long on high will cause it to deform the case.

    If my plane saw 15v I’d be on the phone with B&C to get my voltage regulator fixed.

  36. #36
    wireweinie's Avatar
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    Lol. I once blew the rubber sealing plugs out of an old Odessy. Before that, I didn't even know those plugs were there.

    Web
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  37. #37
    cubflier's Avatar
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    It's hard to tell from your posts if your regulator is outputting 15+v all the time or is it sometimes 15+ and then cuts out or appears to charge at 12v? Also do you have a B&C LR3(B or C) brand regulator?

    If it's a B&C LR3 type, in addition to the trouble shooting steps in the B&C (assuming that's what you have?) installation instructions there are two other I use that seem to help.

    1) Check the voltage between the ground at your battery and the ground of the regulator. This should be zero or very close. Any reading here will be amplified by the two reference diodes inside the B&C regulator and will change in a disproportional amount the output to the field windings(which elevates charging output) and the base of the crowbar latch that is designed defibrillate your expensive electronics as it pops your bus circuit breaker.

    2) Check for continuity between pin 4 and 6. If it exists then your output transistor (the thing on the outside of the case) is shorted and your regulator is running wide open. I don't think this is your problem but worth checking.

    If all connections are true and the trouble shooting guide steps test ok, then see if your new battery charges ok. If it still charges at an elevated voltage then there is an adjustment screw on the regulator. Per the instructions adjust it to factory setting making sure you are checking the output voltage at the battery.

    Good Luck - Jerry
    Last edited by cubflier; 12-06-2018 at 01:57 PM.
    If it looks smooth...it might be

    If it looks rough...it is!!
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  38. #38

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    The 10 amp setting on my cheapo Century charger will run right over 15v on a small batt, I only use smart wall blobs on small agms.
    What's a go-around?

  39. #39
    wireweinie's Avatar
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    'Cheapo charger' sounds like the operative phrase. Check the voltage on a lower setting, if available. If not, don't use it I guess.

    Web
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  40. #40
    Eddie Foy's Avatar
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    I like battery tenders. I still keep a manual charger to get some life in a lead acid battery because some "smart" chargers can't deal with a fully discharged battery. Lead acid batteries will eventually go the way of the dinosaur. IMHO.
    "Put out my hand and touched the face of God!"
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