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#21
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dirty oil
Dan Luke wrote:
wrote: Definitely have an A&P borescope that engine. Broken ring maybe. Talked to my mechanic this morning. He said not to worry; the dirty oil is from the oil cooler and its plumbing, which don't get drained when the oil is changed. Should I pay to have the cylinders 'scoped? Not sure I would completely believe this one. less than 1qt in 8 should not turn the oil black. It will discolor it but it should not be black. We had the oil in an engine on one of our 337s turn black in a couple of hours. I talked to my boss (also an A&P) about this and we pulled the engine and replaced it. Something was definitely wrong. Michelle |
#22
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dirty oil
there are other possibilities also. Have you changed fuel suppliers,
or maybe gone from avgas to mogas or mogas to avgas? Some fuels burn a bit more slowly than others as a function of just what the actual octane is. If burning slower, it will create more carbon in the exhaust, go past the ring gap,then thru the valve guide clearances. Or, your mixture control could be screwed up, and it's not leaning the way it did. In general, it's good to know what the usual behavior of one's engine is. Black oil soon after change in some engines isn't always evidence of a problem, I drive an old radial engined beast, and even after overhaul, with the clearances and low normal compression, the oil is black in 2 hours, tops. the thing having been designed to run on 70 octane doesn't help, either, with modern hi-octane only. Just thought I'd mention this in case someone else who has the problem panics before they find out it's normal for their engine. Looking in the rocker boxes is a good start, however. |
#23
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dirty oil
So, Dan, how did this turn out?
"Dan Luke" wrote in message ... The oil in my Lyc. O-360 F1A6 is black only two hours after being changed. What could be causing this? Compressions were in the 70s at annual in September. -- Dan C172RG at BFM |
#24
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dirty oil
"Stan Prevost" wrote: So, Dan, how did this turn out? No unusual deposits under the valve covers. The airplane is going into Teledyne Continental's shop in Fairhope tomorrow to have the cylinders scoped. Will advise. -- Dan C172RG at BFM |
#25
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dirty oil
"Stan Prevost" wrote:
So, Dan, how did this turn out? Friday, I took the airplane to Teledyne Continental's shop in Fairhope, AL for a "second opinion" on the engine. Just got the report: the engine seems fine. Compressions are ok, crankcase pressure is ok, cylinders all looked good when bore-scoped. This mechanic said the same thing my regular mechanic said about the dirty oil: it most likely came from the oil cooler and associated plumbing which doesn't get drained at oil change unless you pull a line off the cooler. -- Dan C-172RG at BFM |
#26
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dirty oil
No one I know breaks the connections and drains the cooler at routine oil changes... if the oil is changed before it turns black then the oil cooler will not have black sludge left in it.. The contained oil will be no dirtier than what was drained and is diluted by the fresh oil... Frequent oil changes is the solution... Now, if you have a pan heater and you are coking your oil with so called 'preheats' than that residue and char will collect where the oil flow is the lowest, which is the cooler where the Vernatherm stops the flow... The cure is to stop using the pan heater... If you recently changed oil types to one that is more aggressively detergent which acted as a solvent and loosened the gunk in the cooler, then this is likely a one time issue... A self curing situation... GL .... denny |
#27
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dirty oil
Thanks for the update, Dan, and glad it is not anything serious. Someone
said that as long as the engine makes full power and doesn't make metal, don't worry about compressions etc. Presumably that covers black oil too. Stan "Dan Luke" wrote in message ... "Stan Prevost" wrote: So, Dan, how did this turn out? Friday, I took the airplane to Teledyne Continental's shop in Fairhope, AL for a "second opinion" on the engine. Just got the report: the engine seems fine. Compressions are ok, crankcase pressure is ok, cylinders all looked good when bore-scoped. This mechanic said the same thing my regular mechanic said about the dirty oil: it most likely came from the oil cooler and associated plumbing which doesn't get drained at oil change unless you pull a line off the cooler. -- Dan C-172RG at BFM |
#28
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dirty oil
("Denny" wrote)
No one I know breaks the connections and drains the cooler at routine oil changes... if the oil is changed before it turns black then the oil cooler will not have black sludge left in it.. The contained oil will be no dirtier than what was drained and is diluted by the fresh oil... Frequent oil changes is the solution... Doing our (vehicle) oil changes, I drain the old oil. I use a "flush filter" that goes on next. I add (less expensive oil) and run the car for 20 minutes - while I clean up from the first batch. On my second oil change, the "flush filter" gets drained and returned to its (labeled) box on the shelf. A fresh filter is used, then I add my good oil and I'm all set. When I do it this way in my cars, the oil stays golden (like new) for 3,000 miles. If I do it the normal way, my drain oil looks like ...drain oil, after 3,000 miles. Does anyone do this with their planes - an oil flush, then a change? For our cars, it adds about $5 to a driveway oil change. I buy a new "flush filter" every year. Montblack-gold |
#29
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dirty oil
In article ,
"Montblack" wrote: Does anyone do this with their planes - an oil flush, then a change? I don't. -- Bob Noel Looking for a sig the lawyers will hate |
#30
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dirty oil
On 5 Mar 2007 12:55:43 -0800, "Denny" wrote:
No one I know breaks the connections and drains the cooler at routine oil changes... if the oil is changed before it turns black then the oil cooler will not have black sludge left in it.. The contained oil will be no dirtier than what was drained and is diluted by the fresh oil... Frequent oil changes is the solution... Lordy, I don't even have a filter and the oil is black when I change it at 25 hours. However it takes it 15 to 20 hours before the new oil darkens much. Now, if you have a pan heater and you are coking your oil with so called 'preheats' than that residue and char will collect where the oil flow is the lowest, which is the cooler where the Vernatherm stops the flow... The cure is to stop using the pan heater... I use the Tanis which is temperature controlled or rather limited. It'll peak at somewhat under 50C. Hot enough if you just stick your hand in there you will jump back, but cool enough that when you expect it you can put your hand on the pan or cylinder heads and leave it there. Dipstick sump heaters are notorious for coking up. If you recently changed oil types to one that is more aggressively detergent which acted as a solvent and loosened the gunk in the cooler, then this is likely a one time issue... A self curing situation... Remember the old cars that got a dose of detergent oil after years of non detergent? GL .... denny 73 Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com |
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