O-235-C1 Oil Temperature

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Sector95

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I've been struggling with oil temperatures on my 7ECA, hoping you folks might have some advice.

Today was 95 degrees, which is admittedly warm, but my cylinder head temperatures weren't out of hand, right around 330 in cruise @ 2300 RPM. Oil temperatures still climbed to redline and I had to pull power back to around 2000-2100 RPM to get the temperatures to start dropping, and even then it wasn't significant.

I did an oil change after I landed, since the oil already had 40 hours on it and I figured having just run so hot it might be wise.

I then decided to fly again after the oil change, now 80-85 degrees, and again in cruise oil temperatures steadily climbed to 235 before I opted to head back and call it a day. Total time in climb and cruise power was maybe 15-20 minutes.

We tested the oil gauge with hot water, seems accurate, so I don't think it's a bad gauge. My aircraft has a Casper Labs oil filter adapter on it, which is where my oil temperature probe screws in. Any chance that might cause errant readings?

At annual, one of my mags was overhauled and both were retimed. Is it possible the previous owner has the timing intentionally retarded to manage temperatures? I don't recall having issues this severe last year.

Or is this normal for O-235's and I'm chasing a ghost?
 
Hi,

If memory serves me correctly that engine does not have an oil cooler installed as standard.
If it does not, it could be a issue and you may need to install one.

Magneto timing that is incorrectly set will most certainly cause that issue.

Other possible issues could be engine cooling baffling age, condition and how well sealed is it inside the engine cowling. I have seen 0235 Lycoming engines with oil coolers installed but it involved an adaptor fitting in conjunction with the oil filter adaptor.

Good Luck, Brian
 
Slipinonfinal said:
Hi,

If memory serves me correctly that engine does not have an oil cooler installed as standard.
If it does not, it could be a issue and you may need to install one.

Magneto timing that is incorrectly set will most certainly cause that issue.

Other possible issues could be engine cooling baffling age, condition and how well sealed is it inside the engine cowling. I have seen 0235 Lycoming engines with oil coolers installed but it involved an adaptor fitting in conjunction with the oil filter adaptor.

Good Luck, Brian
Click to expand...

I think I'm going to need to install an oil cooler at this point as well. Any idea where I can source an adapter from? The Lycoming one I've seen referred to seems impossible to find.
 
Is this the darn-near bulletproof engine supplied with thousands of early 7ECAs? If so, you shouldn’t need anything beyond what has successfully flown in those aircraft for over a million flight hours. Check the timing, make sure the baffles go up and forward, and remember - the oil temp is in the green arc all the way to 245. Green arc means normal operating temperature.
 
Bob has a good point here on the tried and true of this engine. Confirm that the timing on both Magnetos is correct first. A competent experienced person such as a A&P must check those Mags as it's too easy to screw that up. Also if only one mag is firing that will also cause the engine to run hot as well. (which means you should be doing a mag check on the ground prior to flight to confirm both are functional) Lots of pilots only do it on the first flight of the day. You can forget to turn a magneto on, believe me I know. Humans get distracted. A mag check every time helps prevent that from happening. Live by the check list.

If you still need a oil cooler and adaptor for that 0235 you will prob have to contact a good aircraft engine overhaul facility.

I have received a lot of good advice over the years from this and the old Yahoo citabria pilots group web site which is why I write here as I want to pay it forward. Remember you can get lots of helpful advice here as a great brain trust on this web site but it will never replace a competent set of eyes as that of a experienced A&P looking at your issues there ON THE GROUND.

Cheers, Brian
 
Thanks for the replies guys, I am working with the A&P that did my annual, just doing some homework and collating some data before deciding on what the best path forward is. Baffles look brand new, tight, and are up-and-forward (in fact I get compliments on the baffles when folks see them). Cylinder head temperatures seem to be totally kosher, so I _think_ it's getting adequate cooling. Should I just be expecting the oil temperatures to redline in 90+ degree weather? Other aircraft I'm flying with don't seem to have any cooling issues on those same days, granted they're different engines. It heats up so quickly that I can't really ever get any altitude on hot days, will be at redline in 15-20 minutes where I have to pull power way back to get it to cool.

Here's a picture from Friday, which was the warm day mentioned in my first post, after the temps had already spiked and I pulled power way back. As you can see, I hadn't even made it to 2000 feet yet.
PXL_20230429_005555903~2.webp

Did a little experiment today, which was much cooler day (65F). Curious to hear your thoughts on the validity of the test, as the results are kind of interesting (I'm wondering if it's just wishful thinking).

Compared temp gauge to thermocouple, both gauges agree throughout the range up to 210.

Then on the airplane, I put a sticky thermocouple pad on the oil filter and ran the lead into the cabin (the cooling fins are from the previous owner, I'll give some more background at the end of the post):
PXL_20230501_012613705.webp

When flying at ~2350 RPM in level flight at about 100 MPH, cylinder temps at 330F: oil temp gauge reads about 215F, while the thermocouple is reading ~194F, about a 20 degree delta.

When descending into the airport at landing, ~2050 RPM, 103 MPH, cylinder temps at 245F: oil temp gauge reads about 185-190F, while the thermocouple is reading ~176F, about a 10-15 degree delta.

Is it at all possible that the gauge is just reading hot at that location? Or is the oil filter surface not a very accurate reading location?

I get the sense that the previous owner was chasing this issue as well, due the fact that there is a new temperature gauge, new baffles, and a kind of janky blast-tube setup to the fins on the oil filter. He put on the Casper Labs oil filter adapter, which is where the temperature probe goes into, and when I talked to him he mentioned that he hadn't actually ran the airplane in the summer without it, so he couldn't tell me if it reported cooler with the oil screen.
 
Are you saying the engine was modified for the filter, and the temperature sender was moved somehow?
 
Bob Turner said:
Are you saying the engine was modified for the filter, and the temperature sender was moved somehow?
Click to expand...

The temperature probe in the stock configuration goes into the back of the oil filter screen housing as I understand it. With the oil filter adapter, the temperature probe now sits in the back of that fixture:

temperature probe.webp
 
How difficult is it to convert back for a test flight? This really is a bulletproof airframe/engine combo. Surprised you haven’t received comments from other owners.
I taught my neighbor to fly in one - it has been gone for a decade, but I recall zero problems.
 
Bob Turner said:
How difficult is it to convert back for a test flight? This really is a bulletproof airframe/engine combo. Surprised you haven’t received comments from other owners.
I taught my neighbor to fly in one - it has been gone for a decade, but I recall zero problems.
Click to expand...
Can't imagine it's too hard, I'll give that a go this weekend. Everything I've read has basically echoed your sentiment, so I'm suspecting (hoping) that it's just an inaccurate reading for whatever reason.
 
You might consider purchasing an IR non-contact temperature gun. It would take only a minute to scan sump, oil filter, and oil temp pickup and compare them to the gauge. I bought one of those guns several years ago and find it useful for all sorts of stuff.
 
Sector95 said:
Can't imagine it's too hard, I'll give that a go this weekend. Everything I've read has basically echoed your sentiment, so I'm suspecting (hoping) that it's just an inaccurate reading for whatever reason.
Click to expand...
for what it's worth, the 7ECA that I had originally came to me with an airwolf remote oil filter and I couldn't get an accurate oil temp reading from where the sender was mounted in the adapter fitting. we removed it and installed a B&C oil filter adapter and everything was perfect after that.
 
Wow interesting, So now we have on record possibly two different oil filter adaptors that by design don't have a good oil temp pickup point. That deserves a survey of 7eca aircraft with the 0235 lycoming and an oil filter adaptor out there with the same issue's. Will be interesting to see Sector95 results running just the oil screen and standard oil temp bulb location.
 
Bartman said:
for what it's worth, the 7ECA that I had originally came to me with an airwolf remote oil filter and I couldn't get an accurate oil temp reading from where the sender was mounted in the adapter fitting. we removed it and installed a B&C oil filter adapter and everything was perfect after that.
Click to expand...
Out of curiosity, what tipped you off that the reading was inaccurate? Did it read high or low?
 
Slipinonfinal said:
Wow interesting, So now we have on record possibly two different oil filter adaptors that by design don't have a good oil temp pickup point. That deserves a survey of 7eca aircraft with the 0235 lycoming and an oil filter adaptor out there with the same issue's. Will be interesting to see Sector95 results running just the oil screen and standard oil temp bulb location.
Click to expand...

This is the version of the Airwolf system that my 7ECA had and looking at it now, I'm not sure why they used this one and not the more simple version without the vernatherm (isn't that a vernatherm on the left?).
1683112860733.png

But you can see the port for the sender on the right, it's too deep and I couldn't figure out how the air pocket in there was supposed to bleed out and fill up with hot oil. So we didn't get a reading at all, it usually didn't come off the lower stop unless it was really hot outside. I suspect it was designed for a sender with a longer probe? 😳
 
I am not a fan of airwolf oil filter adaptors but I do know in some instances they are more practical. The down side is they create more possible leak points and in any aircraft engine add on you want less leak points and a low parts count. This product does neither of those. As to the port for the oil sender I can't believe for a minute that the probe just sits in the hole without oil circulation as these temp bulbs are not designed to pick up air temp, oil bath temp only. Also I do not like the older basic oil temp bulb and gauge choices. I do not consider them as accurate. They have some issues in my book. The newer design temp bulbs such as in the E.I. oil temp gauge have a short reach oil temp bulb and I have never had any issue with them reading temp accurately. IMH (opinion)
Thinking now about about sector95 getting the oil filter adaptor pulled and screen put back on! Boy I don't relish that job.
Cheers, Brian
 
Slipinonfinal said:
As to the port for the oil sender I can't believe for a minute that the probe just sits in the hole without oil circulation as these temp bulbs are not designed to pick up air temp, oil bath temp only.
Click to expand...

If someone has one and can explain to me how a short probe gets exposed to the flow of hot oil from where it sits in that cavity, I'd appreciate it. I didn't see it happening and the behavior of the gauge matched what you'd expect from a working probe that wasn't being exposed to hot oil
 
with the B&C, there is no cavity, the sender comes in from the back right into the chamber where all of the oil is.
1683118143828.webp
 
Threw the oil screen back on and went for a flight on a ~65 degree day. Temperatures stayed in the 210-220 range with CHT's right around 300, right about the same as the oil filter adapter. We have some 80-90 degree days coming this week, I'll do a test flight just to make sure, but I don't think it was the culprit at first brush.

In the mean time, any ideas on what might cause higher oil temperatures even with seemingly normal cylinder head temperatures? Or can anyone compare notes with their 7ECA in similar ambient temperatures?
 
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