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#11
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Oil comsumption in IO-540 C4B5 in Aztec
Hi Ronnie,
Between the Wisconsin weather and a funky DG, we haven't been able to fly enough to figure out if we've solved our leak. We found that the base of the dipstick/filler tube was loose. We also noticed that there was no oil staining in front of the tube but plenty on the aft side of the tube. Since we've tightened that up and re safety wired it, we haven't flown. Next time the bottom cowls come off, the oil return lines will all get checked and double checked. Our experience with IO-540's started with when we leased a 182RG. Although it had a different model of the IO540, was derated to 235hp, and no doubt had a different sump, pickup, and breather arrangement, the POH recommended that the oil be filled to 12 quarts before extended trips but that 8 quarts was the normal level. Apparently, Cessna wanted you to "top it off" before a long cross country, let it blow out any excess and you'd have plenty of oil left for the remainder of the trip. We've sort of followed the same routine with the Aztec. Most of our trips are several hours long so when ever we change oil they get filled with 12 quarts + enough to fill the filter. Then we let them blow out the extra quart or two and they seem to stabilize at 10 quarts after about 5 hours. ( the first quart will blow out after about 2 hours, then the next it takes at least another 3 hours) Both engines will stay at 10 quarts for another 10 hours. So, infact it actually takes over 15 hours to have them below 10 quarts if filled to 12 beforehand. They really don't seem to burn hardly any oil. One engine is a 600 hour Penn Yan, and the left is a 1850 hour Mattituck with 400-500 hour cylinders. Even with the drip on the left engine, it was never enough to notice on the dipstick, even after 10 hours at the 10 quart level. I'll pass on the extra leaks.... we're pretty spoiled. Our right engine doesn't leak a drop, so when I see a few on the left, I freak! Guess I need some round engine time and maybe I'd get used to it! Jim "nobody" wrote in message om... Hi Jim, I wondered if you ever found the source of the oil leak / drip problem you were chasing? The idea that this make be a drip out of the air box after oil has seeped down from the top of the air box sounds reasonable. Both engines on my Aztec leak and drip. If I ever went into the hangar and did not find some oil under the engines, I'd think someone had washed the floor within the last 30 minutes! Seriously, we'd have lots of leaks on the oil return lines. The little rubber hoses and associated hose clamps were a nightmare to get leak-proof. I was curious about your oil consumption. You stated you could go 10 hours if filled to the 10 quart level. Our will not do that. At 10 quarts, each engine will be a quart low after a couple of hours. At the 9 quart level, they will run for 4 to 5 hours before being a quart low. I'm nervious about letting them get before 8 quarts, but I'm wondering if they would run at the 8 quart level for a much longer period of time. My Cessna 172 with its O320 sits happily for hours on end at the 6 quarts level, while filling it up to its 8 quart capacity results in losing 2 quarts in a few hours. Scaling this to the IO-540 with the 12 quart sump equates to 9 quarts being the 75% full point, and I'd think that the level would be stable. But I don't see that on my IO-540s. Both engines are high time, but one has less than a 100 hours on all new cylinders, yet both behave the same. This makes me think that the oil loss is in the crankcase and is not being burned. Sounds like yours are stable at 10 quarts. I guess we've more or better leaks than you. Let me know if you need some :-) Ronnie "Jim Burns" wrote in message ... Why would a cold engine drip oil out of the breather? If you're bored or have any answers... read on. Lycoming IO-540 C4B5 Like some of the other owners in the group, we've had a mystery oil leak on one of our engines. Nothing severe, not enough to show up as "missing" on the dip stick. Primarily just a nuisance. Last week ours took on a new characteristic that I can't figure out, so I'll throw a few details at the group to see what tid bits of knowledge, experience, and plain ole guessing can be generated. Original leak seemed to be coming from around an oil return hose on our #3 cylinder. Nearly impossible to get my hands on with the bottom cowl in place, I tightened it up as much as I could without replacing the hose clamp. Occasionally notice a drop of oil hanging from the bottom of the inboard end of the hose. Oil accumulates along the back side of the fuel injector throttle body in a valley where the throttle body moves upward to connect to the air intake scat tube. Small amounts of oil are obviously flying around inside the cowl as single drops can be found on the bottom of collection points such as bolt heads and flanges. The floor of the bottom cowl never has any streaks, streams, or oil lines but is generally covered with a very thin coat of oil that returns even after washing and wiping it down. The above observations were constant all summer when using Aeroshell W100. Never displacing an amount that was observable as a loss on the dipstick. Normally both engines use about a quart of oil every 6-8 hours if we fill them up to 12 quarts. If we leave them down around 10 quarts, they can go up 10 hours before needing to add a quart. Ok, new observations and clues. As winter approached we changed oil and filters and switched from W100 to 15W-50. We've flown about 10 hours on this oil change so far, but this is what I've noticed. A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor directly under the breather tube the day AFTER as short 30 minute flight. The plane came out of a heated hanger and was completely warm and toasty, I flew it home, tucked it away, no drips or drops as I left our old unheated hanger. The NEXT evening I went up to the hanger and the puddle was discovered. I wiped it up, opened the cowls, looked around and everything seemed as described above (a few drops hanging here and there, oil along the backside of the throttle body ect.) The following night, I needed to shovel the snow away from the hanger door, so I went in and there it was AGAIN! The plane hadn't moved, hadn't flown, engines not started, but it dripped another 2 tablespoons full of oil out of the breather tube and onto the floor. The oil I wiped up off the floor is usually darker colored than the oil on the dipstick. So here's what's got me puzzled.... why would a cold engine drip oil out of the breather? Especially the day AFTER it was flown? I can understand if there was pressure remaining in the sump there may be some spit out the breather, but after 24 hours, I can't believe there would be any pressure in the sump. Second thought, which I've been told Lycoming's don't have a problem with, would be a leaking intake valve guide. Could that be seeping oil back down through the intake and somehow make it to the throttle body? One of the breather lines goes to the back side of the throttle body and then (I assume, can't see it) enters the sump. The other breather line goes up towards the back of the accessory case, towards the oil pump I believe, I need to investigate this line more, I couldn't see very well. Any ideas? Thanks! Jim |
#12
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Oil comsumption in IO-540 C4B5 in Aztec
Thanks. I may do a little testing at the 6 to 7 quart level
and see how the consumption looks after an hour. Ronnie wrote in message . .. When most of these engines were certified, the rule was a gallon of oil for each 100 hp. You shouldn't have a problem running down in the 4-6 quart range. It all depends where the oil pickup is. Every pickup I've seen would run oil in the 2-3 quart range without problems. With this, I'm still most comfortable in the 6-8 quart range. Its nice to have that buffer zone of excess oil. nobody wrote: Hi Jim, I wondered if you ever found the source of the oil leak / drip problem you were chasing? The idea that this make be a drip out of the air box after oil has seeped down from the top of the air box sounds reasonable. Both engines on my Aztec leak and drip. If I ever went into the hangar and did not find some oil under the engines, I'd think someone had washed the floor within the last 30 minutes! Seriously, we'd have lots of leaks on the oil return lines. The little rubber hoses and associated hose clamps were a nightmare to get leak-proof. I was curious about your oil consumption. You stated you could go 10 hours if filled to the 10 quart level. Our will not do that. At 10 quarts, each engine will be a quart low after a couple of hours. At the 9 quart level, they will run for 4 to 5 hours before being a quart low. I'm nervious about letting them get before 8 quarts, but I'm wondering if they would run at the 8 quart level for a much longer period of time. My Cessna 172 with its O320 sits happily for hours on end at the 6 quarts level, while filling it up to its 8 quart capacity results in losing 2 quarts in a few hours. Scaling this to the IO-540 with the 12 quart sump equates to 9 quarts being the 75% full point, and I'd think that the level would be stable. But I don't see that on my IO-540s. Both engines are high time, but one has less than a 100 hours on all new cylinders, yet both behave the same. This makes me think that the oil loss is in the crankcase and is not being burned. Sounds like yours are stable at 10 quarts. I guess we've more or better leaks than you. Let me know if you need some :-) Ronnie "Jim Burns" wrote in message ... Why would a cold engine drip oil out of the breather? If you're bored or have any answers... read on. Lycoming IO-540 C4B5 Like some of the other owners in the group, we've had a mystery oil leak on one of our engines. Nothing severe, not enough to show up as "missing" on the dip stick. Primarily just a nuisance. Last week ours took on a new characteristic that I can't figure out, so I'll throw a few details at the group to see what tid bits of knowledge, experience, and plain ole guessing can be generated. Original leak seemed to be coming from around an oil return hose on our #3 cylinder. Nearly impossible to get my hands on with the bottom cowl in place, I tightened it up as much as I could without replacing the hose clamp. Occasionally notice a drop of oil hanging from the bottom of the inboard end of the hose. Oil accumulates along the back side of the fuel injector throttle body in a valley where the throttle body moves upward to connect to the air intake scat tube. Small amounts of oil are obviously flying around inside the cowl as single drops can be found on the bottom of collection points such as bolt heads and flanges. The floor of the bottom cowl never has any streaks, streams, or oil lines but is generally covered with a very thin coat of oil that returns even after washing and wiping it down. The above observations were constant all summer when using Aeroshell W100. Never displacing an amount that was observable as a loss on the dipstick. Normally both engines use about a quart of oil every 6-8 hours if we fill them up to 12 quarts. If we leave them down around 10 quarts, they can go up 10 hours before needing to add a quart. Ok, new observations and clues. As winter approached we changed oil and filters and switched from W100 to 15W-50. We've flown about 10 hours on this oil change so far, but this is what I've noticed. A puddle of oil, I'd say about 2 tablespoons full, appeared on the floor directly under the breather tube the day AFTER as short 30 minute flight. The plane came out of a heated hanger and was completely warm and toasty, I flew it home, tucked it away, no drips or drops as I left our old unheated hanger. The NEXT evening I went up to the hanger and the puddle was discovered. I wiped it up, opened the cowls, looked around and everything seemed as described above (a few drops hanging here and there, oil along the backside of the throttle body ect.) The following night, I needed to shovel the snow away from the hanger door, so I went in and there it was AGAIN! The plane hadn't moved, hadn't flown, engines not started, but it dripped another 2 tablespoons full of oil out of the breather tube and onto the floor. The oil I wiped up off the floor is usually darker colored than the oil on the dipstick. So here's what's got me puzzled.... why would a cold engine drip oil out of the breather? Especially the day AFTER it was flown? I can understand if there was pressure remaining in the sump there may be some spit out the breather, but after 24 hours, I can't believe there would be any pressure in the sump. Second thought, which I've been told Lycoming's don't have a problem with, would be a leaking intake valve guide. Could that be seeping oil back down through the intake and somehow make it to the throttle body? One of the breather lines goes to the back side of the throttle body and then (I assume, can't see it) enters the sump. The other breather line goes up towards the back of the accessory case, towards the oil pump I believe, I need to investigate this line more, I couldn't see very well. Any ideas? Thanks! Jim |
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