Hello, fellow ‘Coupers, William E. Dubois of “Race 53” here. I hope you’ll forgive a long post, but I’m at my wit’s end and I need advice. Our ’47 CD is suffering from over-heating oil. I’m redlining at 225 within 20 minutes of lift off, in level flight at 2500 rpm, and if I don’t back off, it creeps higher. We’re flying a mile above sea level, mixture set for peak EGT. I check temps on two cylinders, the back left runs 450, and the right front runs 400. EGTs are normal (the right lower). This is on a rebuilt C-85 with the 0-200 stroker conversion. Here’s the weird thing, however: After the initial (epic) problems with this engine that I’m sure many of you have read about, it ran fine for a year or so, at least as far as temps. We had put in an electronic engine monitor, but it drove me batty: The tac was hyper sensitive, we could never get the fuel flow programed right, the screen was hard to read from reflections, and the EGT leads frequently came off and caused all kinds of alarms. I had a Luddite hissy-fit and put steam gauges back in at the next annual, aided by the offer of a refund from Electronics International, who were tired of dealing with my frequent calls and emails. With the steam gauges back in, for the first time on this engine, I starting seeing oil temp problems. Other issues, including a hard landing that took the plane out of service for many months replacing stringers and skin on the nose, followed in rapid order by a front fork rebuild, then a replacement Tmast have all resulted in this plane flying VERY little in the last few years. (((sigh))) I really miss flying. Anyway: I’ve switched to 100W from the multigrade, patched a few holes in the upper baffling, and have tested the oil sender using a meter, boiling water, and a hair dryer. It’s working fine. The baffling is not the standard “chimney” type shown in the parts manual, but rather shields that guide air around the lower cylinders. It’s been pointed out to me that this could be an issue, but if the temperature readings on the digital monitor were to be believed (Oil, Head, and exhaust) it seemed to work fine. What could be going on inside my engine to overheat oil and not be overheating the engine overly much, and what should I try next?
