Tracking down an oil leak on our RV10 was a long and time-consuming process. We spoke to our neighbors and friends and other RV10 builders and the great folks at Barrett Precision Engines. Many people combed over the engine and gave us ideas to try. In the end it took weeks and about 50 hours of flying to figure out--very disheartening each time to think ?We got it!? only to fly again and see just as much oil as before all over the bottom cowl and belly. But finally, we did find the culprit.
Right from the start, we had oil flowing out the bottom of the cowl area at about a quart every 2 hours. The oil was pooling on the pilot side, bottom cowl and blowing out the back, all the way to the tail light. The first guess was the oil quick drain, as it was closest to the pooling. Maybe it had a bad o-ring, or it was getting hit by something. We swapped that out for a plug. No difference.
Based on posts on Van?s Airforce, and talking to folks, the oil breather tube routing was the next guess. The theory was that air inside the cowl was blowing in such a way to suck out the oil. The inside of the bottom of the breather was always slick with oil. Over the next few weeks, we changed its shape, the direction it faced, made it longer to extend below the cowl, even put a hole in the back as was done on our Cardinal, to mitigate suction. None of this changed anything.
Many people claimed that they had the same problem and installing the Anti-Splat Oil Separator cured it. Our thought was that we wanted to make sure we solved a potentially big problem rather than just applying a band aid, so we held off on the oil separator for a long time. Fearing that the rings had not seated or that the cylinders might be glazed, we tested compression, internal engine pressure with a manometer in the oil filler opening, boroscoped the cylinders, checked the mags. All were fine.
At this point we gave up and installed the oil separator. This moved the oil breather line from the Pilot?s side to the Copilot?s side of the airplane. And then we found an interesting thing, the oil was still pooling on the pilot?s side cowl and down the nose gear, just as much as before.
Monty Barrett was a great help in helping us track this down. We would find oil and send him a picture or call him on the phone. And he would tell us that was not likely to be the problem.
Scratching our heads and thinking back to finding leaks on my Cardinal RG I remembered that we used to spray foot powder on the engine to find an oil leak. So, I bought a couple of cans of spray foot powder and sprayed down the engine and flew the plane. When we landed oil was dripping out of the cowl and we took it off again and called Monty. At one point during the series of calls it looked like the oil was coming from the fuel pump, and he thought that unlikely. And then our friend Joe Migis found that there was oil on the bottom of the BandC 90 degree oil filter adapter with an inspection mirror. We checked the oil temp probe and it was tight, and then we called Monty Barrett and he said to check the crush washer.
Bingo. Sure enough it was where the leak was coming from, it has been put in so that their was a directed leak right down a hose to another hose and right to the Pilot?s side cowl near the nose gear. Under pressure the oil sprayed in the single perfect direction to miss every other hose, control line, engine mount, and most of the firewall. One of our neighbors had a crush washer and there is no longer an oil leak on the Barrett Engine on our RV10.
The oil leak through the oil temperature crush washer was one of the most difficult problems July and I had on the RV10 project. We could not have found it without the old foot powder trick and a lot of phone calls and advice from our friends.
Right from the start, we had oil flowing out the bottom of the cowl area at about a quart every 2 hours. The oil was pooling on the pilot side, bottom cowl and blowing out the back, all the way to the tail light. The first guess was the oil quick drain, as it was closest to the pooling. Maybe it had a bad o-ring, or it was getting hit by something. We swapped that out for a plug. No difference.
Based on posts on Van?s Airforce, and talking to folks, the oil breather tube routing was the next guess. The theory was that air inside the cowl was blowing in such a way to suck out the oil. The inside of the bottom of the breather was always slick with oil. Over the next few weeks, we changed its shape, the direction it faced, made it longer to extend below the cowl, even put a hole in the back as was done on our Cardinal, to mitigate suction. None of this changed anything.
Many people claimed that they had the same problem and installing the Anti-Splat Oil Separator cured it. Our thought was that we wanted to make sure we solved a potentially big problem rather than just applying a band aid, so we held off on the oil separator for a long time. Fearing that the rings had not seated or that the cylinders might be glazed, we tested compression, internal engine pressure with a manometer in the oil filler opening, boroscoped the cylinders, checked the mags. All were fine.
At this point we gave up and installed the oil separator. This moved the oil breather line from the Pilot?s side to the Copilot?s side of the airplane. And then we found an interesting thing, the oil was still pooling on the pilot?s side cowl and down the nose gear, just as much as before.
Monty Barrett was a great help in helping us track this down. We would find oil and send him a picture or call him on the phone. And he would tell us that was not likely to be the problem.
Scratching our heads and thinking back to finding leaks on my Cardinal RG I remembered that we used to spray foot powder on the engine to find an oil leak. So, I bought a couple of cans of spray foot powder and sprayed down the engine and flew the plane. When we landed oil was dripping out of the cowl and we took it off again and called Monty. At one point during the series of calls it looked like the oil was coming from the fuel pump, and he thought that unlikely. And then our friend Joe Migis found that there was oil on the bottom of the BandC 90 degree oil filter adapter with an inspection mirror. We checked the oil temp probe and it was tight, and then we called Monty Barrett and he said to check the crush washer.
Bingo. Sure enough it was where the leak was coming from, it has been put in so that their was a directed leak right down a hose to another hose and right to the Pilot?s side cowl near the nose gear. Under pressure the oil sprayed in the single perfect direction to miss every other hose, control line, engine mount, and most of the firewall. One of our neighbors had a crush washer and there is no longer an oil leak on the Barrett Engine on our RV10.
The oil leak through the oil temperature crush washer was one of the most difficult problems July and I had on the RV10 project. We could not have found it without the old foot powder trick and a lot of phone calls and advice from our friends.
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