Big day here today. We’ve been fighting oil temps something fierce. This week we installed a new, larger, Positech oil cooler on the firewall and installed a new vernatherm (thermostat) into the engine. We put everything together and ran it yesterday, doing our “leaf blower” test and didn’t like the results.

When we got back to the hangar I used my new infrared thermometer to check temperatures at various parts of the engine. Interestingly they all looked good. So, I checked the engine right at the oil temperature probe, and it read about 125F. We switched on the GRT, and it was reading over 160F still. Hmmm, that’s odd. Recall I’d tested this probe with boiling water already, and it read properly, but I’d done everything but put in a new GRT probe so I had it handy. I ran in and grabbed it, donned some gloves, popped out the old BMA sensor and put the new GRT in, and spun the prop some. It read about 125F. Hmmmm, that’s what the IR thermometer says. Winds prevented us from flying yesterday so when I woke up at 7 this morning and saw 70 degrees and calm winds I rousted Elizabeth out of bed. As then engine was warming up, and told her that if-when she turned final-the oil temperature was below 210F, she could (at her option) do a touch-n-go to see if the temperature would continue to climb on a second pattern or if it was stable. At 140F oil temperatures I cleared her to depart. As she turned base she announced that this pass would be a touch-n-go! Yippee! On downwind for the second pass she called that the oil temp was holding steady about 180F! Outstanding! It made for a very pleasant Father’s Day.

So, the question is, was it the sensor or the vernatherm? Dunno. Probably the sensor, and I don’t know why it tested ok. I probably should’ve replaced it at the first sign of trouble. It was the cheapest part anyway, and the only sensor I didn’t get from GRT, so I should’ve just chucked it. Lesson learned, I guess. I won’t be fully convinced we’re out of the woods until we fly when it’s really hot, and happily it’s going to be really hot this week. So, I’ll check out the airplane tonight and make sure everything is as we would expect, safety tie the new sensor and vernatherm, and maybe add the third cooler back into the loop. I still have things to learn, after all. I think this tells me I can leave my third cooler in the loop. I think it also tells me that that I can put my hoses back in (in favor of hard tubed aluminum). We shall see, but we’re on the path again.

I will be traveling all next week, so we’ll get the plane in a stable flying configuration and let Beth get comfy with it while I’m gone, assuming the oil temperature problem really is fixed. Once she’s happy with how the plane is performing, she can start testing all the things we need to reconfirm since painting it. First she’ll do solo stall testing and prove that’s good, then two pilot stalls. Then we’ll work up to speed and check for flutter again. Once that’s out the way, we’ll need to decide if we want to get really comfortable that we can depend on it to get to Osh Kosh and back, or go to Wisconsin for our vinyl work. Time is short, and they need a week to do the decals. I’m leaning towards get happy with plane, get ready for KOSH, dole out a few rides, and get the stickers right after Osh Kosh. But, it is really tempting to try and doll her up for Osh Kosh. Watch this space.

Posted By: Brett Ferrell
Sunday June 20th, 2010 at 9:57 PM

Categories: Blog
Tags: Blog

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