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Recently purchased (February) AA1B with STC for O-290 installation. Now that warmer weather is here I am having issues with uncomfortably high oil temperatures, curtailing my flying any time the ambient (ground) temps are above 80F. First time I noticed the issues ambient was around 85F and the oil temperature was running at the top of the green (230F to 240F, red-line is 245F) while in cruise at 2500 MSL @ 2300RPM. This made for a very uncomfortable (and short) flight!!
Baffling is not new, but I’m not seeing any obvious gaps. Oil cooler air flow is unimpeded as I checked the back side if the fins with a camera, and the flow thru the fins looks ok with light showing thru from flashlight on back side.
Looking for some ideas and/or a starting point for troubleshooting the issue. This will make the airplane unusable here in North Texas during the summer. Thanks!!
Jeff – AA1B-0625
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My AA-1B is fitted with an 0320-A2B that I installed in 1983. I have gone through periods of fighting high oil temps also. Being yours is a ’76 B model like mine, you have the added advantage of the larger inlet nose cowl (square inlets).
Areas I have had issues with in the past (other then baffling) has been the oil thermostat valve not fully opening, and blow-by on the rings.
How quickly does the oil darken after oil change? Is it black after only say 5 hours? Exhaust gases going into the case will greatly heat the oil. Do a compression check and listen for air blowing into the case and out the vent.
My baffles are not perfect, but at about 350 hours since O/H my oil temp stabilizes about 190 in the summer.
Rich
AA1B-0632 -
Hey Jeff,
Sorry to hear you are dealing with High oil temps. I just went through that issue on my AA1A with a O290D2. I ended up replacing my engine! but I learned a lot trying to fix it.
Here is what I recommend. How much oil is coming out of the breather tube? if its a lot and oil is turning black after 2 hours then you have blowby and you need to have new rings or the cylinders OH.
Baffling, I literally sealed everything with liberal amounts of high temp rtv! Also new baffling is cheaper than a smoked engine…
Vernatherm, replace it and have the oil cooler flushed out.
Check all oil lines for any collapsed areas or sharp bends. Replace them if they are older than 8 years old.
Hope that helps
Dan
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