Are you doing aerobatics? If you top off the oil, how quickly does the level go down before stabilizing at some lower level? How are the compressions? Have you ever done an oil analysis?
O-235-C1 Oil Temperature
- Thread starter Sector95
- Start date
Haven't done aerobatics on this oil, but when I do it's pretty tame stuff typically. The plane burns about 1 quart per 10 hours or so. Oil analysis always come back in the green, have a long history of them, previous owner was diligent about that. Have a sample from last change that I just sent in, waiting on its results.
Sorry I thought I had already posted compressions. These were done on a roughly 38 degree day in an unheated hangar, if that's relevant.
65, 67, 68, 62
Last year during prebuy in April they were "75 or better". Year before that with previous owner they were 75, 78, 76, 79.
Fun fact, number 4 actually had *zero* compression this year at annual, but turned out that the valve setting was too tight and just holding the valve a little open when the engine was cold.
I don't know how significant it is to have low compressions from a cold engine on a cold day. If I were you, I'd get the engine warmed up and redo the compression test, you may have answered your own question here.
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Heya everyone, figure I might as well update you folks on my journey since you've been so kind as to help thus far!
Since we last chatted, I completed a series of the diagnostic steps everyone graciously supplied to me here, including another compression test, and hitting the cylinders with a temp gun after a ground run-up. Ambient temperature was about 80F or so, CHT on #3 read 220 at engine shutdown after run-up.
In light of the sudden drop in cold compression since annual, and some scoring on the sidewalls we found during a bore scope, we're going to pursue overhauling the number 4 cylinder to see if we see any improvement, which will likely take 2-3 weeks. I'll keep you all updated!
I do find it interesting that both the cylinders on the pilot's left side of the engine are faring much worse than those on the right, but maybe that's just a coincidence.
Thanks again!
Since we last chatted, I completed a series of the diagnostic steps everyone graciously supplied to me here, including another compression test, and hitting the cylinders with a temp gun after a ground run-up. Ambient temperature was about 80F or so, CHT on #3 read 220 at engine shutdown after run-up.
| Cylinder Number | Compression Cold | Compression Hot | Base Temp | Cooling Fin Temp |
|---|---|---|---|---|
| 1 | 75 | 75 | 155 | ~175 |
| 2 | 64 | 61 | 168 | ~175 |
| 3 | 76 | 74 | 155 | ~175 |
| 4 | 54 | 62 | 180 | 194 |
In light of the sudden drop in cold compression since annual, and some scoring on the sidewalls we found during a bore scope, we're going to pursue overhauling the number 4 cylinder to see if we see any improvement, which will likely take 2-3 weeks. I'll keep you all updated!
I do find it interesting that both the cylinders on the pilot's left side of the engine are faring much worse than those on the right, but maybe that's just a coincidence.
Thanks again!
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glad to hear you are making progress but #2 is very low also, why not pull and overhaul it too?
I was actually having that internal debate earlier; my hesitation comes from the thought that maybe the cylinders failing is a symptom, and not necessarily the root cause. Just odd to me that these cylinders would wear themselves out in just 500 hours for no apparent reason, but I guess to be totally fair, that 500 hours was over 13 years, so maybe not such a stretch to think they might not fare well.
I'll chat with my mechanic on when I meet with him to pull #4, because I do agree with you, it'd be great to have both done and dusted while the plane is down.
If compression gasses are causing your oil temps to run high, I'd guess that getting both #2 and 4 back into fighting shape would solve the problem.
What spark plugs do you use? I switched from 40s to 38s in my ECA and I swear it runs at least 10* hotter. Not uncommon for it to settle in around 235* on a 100* day after an hour of flying
nbainbridge
Member
@Sector95 sorry, late to the thread. B&C is my company. Sometimes we have customers use the Tempest filter with our OFA and get higher temps, then they switch back to a Champion and the temps go back to normal. I have never found a reasonable explanation for this phenomenon, and the Tempest works great 99% of the time. I wanted to mention it in case it helps.
Bob Turner
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Nice that you are here. I use two of your starters on Cubs (TC was a great help) and if the Sky Tek craps out again we will make it three. Good product!
nbainbridge
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@Bob Turner Thanks Bob. We're always working hard for our customers!
November67
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Perhaps a bit late too, but reacting to the compression values of Sector a bit earlier in this thread, according to Mike Bush the compression test is a not very accurate way of telling you how healthy your engine is, for a lot of reasons. If you have the time, take a look at this link:
Slipinonfinal
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To November67,
Mike Busch,
Certainly is savvy however remember that compression checks are still a requirement as he points out and they still can alert you to a maintenance issue with the engine. Compression checks are just one tool in the tool box and other tools can and should be used at the same time. For example spark plug condition, engine monitors can also tell you a bunch if understood and used correctly. I am also a huge fan of engine oil analysis as it is a very economical way of keeping tabs on the heart beat of that expensive beast in front of you.
Cheers, Brian
Mike Busch,
Certainly is savvy however remember that compression checks are still a requirement as he points out and they still can alert you to a maintenance issue with the engine. Compression checks are just one tool in the tool box and other tools can and should be used at the same time. For example spark plug condition, engine monitors can also tell you a bunch if understood and used correctly. I am also a huge fan of engine oil analysis as it is a very economical way of keeping tabs on the heart beat of that expensive beast in front of you.
Cheers, Brian
Slipinonfinal
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To: Nbanbridge,
I met and talked with your Father many times over the years. He was a huge asset to the aviation community. Great company that truly deserves its legacy. Great to see you here on this site!
Cheers, Brian
I met and talked with your Father many times over the years. He was a huge asset to the aviation community. Great company that truly deserves its legacy. Great to see you here on this site!
Cheers, Brian
VaporGlobalAviation
Well-known member
My ECA ran at 230-235 this summer. 100F days. Just out of annual with zero discrepancies. I’ve resigned myself 245F is the max for a reason. Not going to worry about it any longer. Certainly will watch it, but not worry.
Agilestick
1968 Champion Citabria 7ECA - 115hp
This is the first summer I have been flying my Citabria (7ECA - O-235-C1). On the 100F degree days, my oil temp will rise slowly to 240F or thereabouts. On descents, it can drop 20F in 10 mins or so. On a 95F day, the oil temperature will be 220F - 230F which makes sense to me. Oil pressure always sits around 70PSI. I figure that's normal for the engine. CHT is a steady 330F and EGT around 1300F. I have tracked the temps and pressures since I purchased the plane last December.