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Thread: Engine Runs (Ran) Hot

  1. #1
    WindOnHisNose's Avatar
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    Engine Runs (Ran) Hot

    I had my engine overhauled two years ago, had the cylinders "ported and polished" by a reputable outfit in California. 160 hp Lycoming. Overhauled the engine, the Slik mags..."It will be even more hp than 160" I was told by Mark Baker and several notable others. Cost more, but it would be worth it...

    The engine ran hot...like it would go over redline when it was 80 degrees OAT, and I was told that when hp goes up, so does heat. Made sense. Maybe I would need a bigger oil cooler. So, I called Randy Rubbert, Reynolds ND, and he agreed and had a larger capacity oil cooler... which I promptly put on.

    Still, the engine ran close to redline...and again would go past redline when it was hot.

    I was told by some reputable people that the redline was a relatively random data point, that in fact it is not harmful for our engine to run over redline, but that it made our oil break down faster, hence would need an oil change.

    I was advised that this could be a timing issue, so I asked my terrific AI to check it, and it was, indeed, off a bit. But still the engine ran hot.

    I just found out what the right answer was...since it is now running nice and cool, even in warm weather since "the fix".

    What was the fix?

    Randy

  2. #2
    www.SkupTech.com mike mcs repair's Avatar
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    huh?? you skipped some details..

  3. #3
    behindpropellers's Avatar
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    Calibrated the gauge.

  4. #4
    WindOnHisNose's Avatar
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    Calibrated the gauge. Spot on.

  5. #5
    WindOnHisNose's Avatar
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    What details do you want, Mike?

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    WindOnHisNose's Avatar
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    (this is kinda like Click and Clack on NPR)

  7. #7
    WindOnHisNose's Avatar
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    Larry, the A&P, checked the timing of the engine. Slightly off. Corrected, no change in engine temps.

  8. #8
    WindOnHisNose's Avatar
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    At the engine overhaul, the baffling was changed, bought a kit that Roger Meggers felt was the best.

  9. #9
    68Papa's Avatar
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    I'm confused??? What was the fix? Oil temps hot? CHT hot? Calibrated?? Clarify???

  10. #10
    Steve Pierce's Avatar
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    Those original Stewart Warner gauges are all over the place. That engine shop you referenced bought all the spares from a foreign operator of Super Cubs and got a lot of new old stock gauges and they tested them. Verified what I figured out and you have figured out. Very broad tolerences. Mine in my Cub shows cool on the top end and warm on the bottom which is what they figured out during testing, they are not linear.
    Steve Pierce

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  11. #11
    cubdriver2's Avatar
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    Easy to check with a soup can, some oil and a propane torch

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

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    One of my handiest shop tools as an infra red thermometer. It has saved me a lot of grief with airplanes, boats (especially boats) and cars. During the Ebola outbreak it was also a great assurance when I had sick passengers that they were not running a fever without risking exposure. I own three of them. One for the hangar, one for the boat and one for the shop. Good ones are not that expensive.
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  13. #13
    WindOnHisNose's Avatar
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    GeeBee, I used my handy dandy infrared sensor, too, and the temps were right on.

    I might also mention that this engine went from being an easy starter before the overhaul to a much more difficult starter. This was true particularly for hot starts...took a lot of cranking to finally get it to start...would sort of cough and sputter when it did start.

    We checked the baffling, and it was brand-spanking new and so that wasn't it.

    The culprit turned out to be the Slik mags. The e-gap was way off. We had replaced the mags when the engine overhaul was done. Tim pulled one of the Slik mags, found the egap to be way off. He reset the egap.

    This fixed not only the engine temps, but also the starting difficulties. It is a much happier engine now.

    I thought I would share this experience with those of you who have Slik mags, in case this happens to you. We chased this problem for over a year before finding out what the problem was.

    Randy
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  14. #14

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    Did you remove the sensor and put the beam right on the sensor? Engines will have all sorts of hot and cold spots on them, but if you beam the sensor and compare the gauge to the thermometer, quick easy and usually correct.

  15. #15
    www.SkupTech.com mike mcs repair's Avatar
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    internal mag timing issue? (hard start too)

    to high oil quantity?

  16. #16
    www.SkupTech.com mike mcs repair's Avatar
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    duh, just read your other post..

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    Steve Pierce's Avatar
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    Quote Originally Posted by WindOnHisNose View Post
    GeeBee, I used my handy dandy infrared sensor, too, and the temps were right on.

    I might also mention that this engine went from being an easy starter before the overhaul to a much more difficult starter. This was true particularly for hot starts...took a lot of cranking to finally get it to start...would sort of cough and sputter when it did start.

    We checked the baffling, and it was brand-spanking new and so that wasn't it.

    The culprit turned out to be the Slik mags. The e-gap was way off. We had replaced the mags when the engine overhaul was done. Tim pulled one of the Slik mags, found the egap to be way off. He reset the egap.

    This fixed not only the engine temps, but also the starting difficulties. It is a much happier engine now.

    I thought I would share this experience with those of you who have Slik mags, in case this happens to you. We chased this problem for over a year before finding out what the problem was.

    Randy
    That was those bad points they were making. I have had no issues with the new ones. Pulled an IO-540 off an Extra 300 with a couple of holes in the pistons from detonation because of these points.
    Steve Pierce

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    That's great info Doc. I've been fighting high temps and hard starting for 4 years since I had my hot rod engine built with new slick mags by a reputable Ca shop. I think I've put off pulling the mags for way too long while making minor improvements in other areas.
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    If the timing checked correct what was the mechanism that caused the engine to run hot? Would it be weak spark caused by the firing happening at less than maximum magnetic field? Thanks in advance.

  20. #20
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by qsmx440 View Post
    If the timing checked correct what was the mechanism that caused the engine to run hot? Would it be weak spark caused by the firing happening at less than maximum magnetic field? Thanks in advance.
    the INTERNAL timing of the gears in the mag was off...

  21. #21
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by qsmx440 View Post
    If the timing checked correct ...
    that just indicates where the points OPEN/CLOSE

  22. #22
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    I had my engine overhauled two years ago, had the cylinders "ported and polished" by a reputable outfit in California. 160 hp Lycoming. Overhauled the engine, the Slik mags..."It will be even more hp than 160" I was told by Mark Baker and several notable others. Cost more, but it would be worth it...
    Did you have more power?

  23. #23
    WindOnHisNose's Avatar
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    Kase, I do have more power.

    Roger Meggers strongly encouraged me to do the port and polish addition, and I think it has made a difference in hp, but have no data to say that definitively. Lycon, the company who did the porting and polishing, has an excellent track record.

    I really don't have the engineering/mechanical background to understand, much less explain, what the relationship is between the e-gap and engine timing. We "timed" the engine as a means of addressing if that could be why the engine ran hot. That checked out. It was only when we went to the e-gap examination that a problem was identified with the Slik mag, and the engine has run beautifuly since then.

    Today I flew back from Fargo in 85 degree temps, and ran it pretty hard. The temps stayed below 200 degrees, a significant change from what I found before the e-gap was changed.

    I really do hope someone can explain this to me. I just don't get it, but am pleased with the outcome!

    Randy
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  24. #24
    kase's Avatar
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    Thanks Randy, I have another cub engine ready to go together except for the cylinders. Trying to decide if I should have the port/polish done.

  25. #25
    WindOnHisNose's Avatar
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    Quote Originally Posted by kase View Post
    Thanks Randy, I have another cub engine ready to go together except for the cylinders. Trying to decide if I should have the port/polish done.
    Call Roger, Alan!

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    Quote Originally Posted by kase View Post
    Thanks Randy, I have another cub engine ready to go together except for the cylinders. Trying to decide if I should have the port/polish done.
    Do it... they run smoother and produce more power all with more consistent temps and if you're talking to Lycon do a little research and ask about the main jet modification and flow test they can do.
    Last edited by OLDCROWE; 07-17-2017 at 08:08 AM.
    "Don't feed the hipsters"
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    Steve Pierce's Avatar
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    Randy, the points in the magneto wear over time. We check and adjust magneto to engine timing at annual inspections and usually have to adjust the timing a little. That adjustment is to make up for that point wear. With Slick mags after about 500 hours you should pull them and adjust the internal timing (e-gap) because that point wear has changed the internal timing. Slick made all their parts in house, down to the screws. When Champion bought Slick they out sourced most of the parts and made 14 changes at once. They had cam problems, carbon brush problems and the points would wear excessively in the first few hours. I had to pull an AEIO-540 for Ken at LyCon at the US aerobatic contest a few years ago becasue a mag had worn and retarded to 35 degrees in 14 hours, detonated and burned a hole in one piston and started on several more. Had lots of calls from people all over the country trying to diagnose their hard starting issues. Some had changed carburetors and all kinds of other parts. My contact at Champion was very forth coming but Champion was not. They cost a lot of people a lot of time and money. Who makes 14 changes to something at one time. Growing up with my Dad (mechanical engineer) I know that is dumb.
    Steve Pierce

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  28. #28
    Steve Pierce's Avatar
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    LyCon does not port and polish by hand. They have a CNC mill programed to do the work. Ken told me that way they are all the same every time. They do make more power, there are other tricks they do but the big thing to me is the smoothness. Years ago I installed a factory reman on a friend's Dad's Bonanza. He flies 300 plus hours a year and this was his 3rd or 4th factory reman. We got the engine from LyCon, all they did was port and polish the cylinders. Even today when ever I see him he talks about how smooth that engine is, "like flying behind a sewing machine".
    Steve Pierce

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  29. #29

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    When you guys port and polish, is that still normal category? I had an aerobatic engine shop say that he could not do that to my 0-540. Just asking.

  30. #30
    Steve Pierce's Avatar
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    Quote Originally Posted by barijr View Post
    When you guys port and polish, is that still normal category? I had an aerobatic engine shop say that he could not do that to my 0-540. Just asking.
    Some can and some can't. LyCon has the FAA's blessing, Rhonda Barrett told me they can't legally do port and polish on a certified engine.
    Steve Pierce

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    That's what they said, thanks. I have banner towers and if you could could pitch the prop a couple more inches for a little more bite, that would help.

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