MarcF Posted June 20, 2013 Report Share Posted June 20, 2013 Hi, Last morning, during the preflight control, I observed that the oil level was 3 cm above the max while it was at 1 cm below last week end. The oil seems more fluid, and there is obviously fuel inside. Not any linkeage visible on the carburetors or elsewhere. Have you any idea ? Friendly Marc Link to comment Share on other sites More sharing options...
MarcF Posted June 20, 2013 Author Report Share Posted June 20, 2013 I just forgot to say that of course: 1/ I did'nt even try to start the engine, 2/ I removed the spark-plugs and there was no evidence for fuel in the cylinders, 3/ the fuel tap was not fully closed (this explain that fuel could pass through but not where) 4/ I changed the oil and the fuel filter ... Link to comment Share on other sites More sharing options...
CT4ME Posted June 20, 2013 Report Share Posted June 20, 2013 I wouldn't let the fact that there is slightly more/less oil lead you to draw a conclusion. Because of the sump/pump design, and burping, the amount of oil will vary slightly from check to check. Now, if you SEE fuel in there, that's a different thing. Tim Link to comment Share on other sites More sharing options...
MarcF Posted June 20, 2013 Author Report Share Posted June 20, 2013 I agree with you Tim, but I own my CT for 3 years and I never saw the oil level increasing of approximatively 0;3 liter ! Yes I am sure it is fuel ... The engine is 300 hrs old ... Link to comment Share on other sites More sharing options...
Tip Posted June 20, 2013 Report Share Posted June 20, 2013 I had a bad fuel pump which put gas in the oil during flight. Link to comment Share on other sites More sharing options...
Roger Lee Posted June 20, 2013 Report Share Posted June 20, 2013 This can happen. The oil level can change, but fuel can show up in the oil. It is usually very limited and doesn't happen all the time. I wouldn't worry if it is very minor and many times it just goes away because the fuel evaporates after the oil gets hot. I have seen this in many engine so it isn't an isolated issue. Link to comment Share on other sites More sharing options...
MarcF Posted June 21, 2013 Author Report Share Posted June 21, 2013 OK thanks. So I don't worry, but after changing oil, I got 3.3 l instead of 3l in the basin... How can I check the fuel pump ? What am I suppose to look at ? Friendly Link to comment Share on other sites More sharing options...
Roger Lee Posted June 21, 2013 Report Share Posted June 21, 2013 It's rarely the fuel pump, but the only way would be to change it out. Usually bad fuel pumps have some weeping liquid coming out the bottom weep holes. Link to comment Share on other sites More sharing options...
MarcF Posted June 21, 2013 Author Report Share Posted June 21, 2013 Thanks a lot ! Link to comment Share on other sites More sharing options...
Tip Posted June 21, 2013 Report Share Posted June 21, 2013 Marc, My fuel pump started weeping oil at the end of a 3 1/2 hour cross country and oil was on my windscreen. But, the first indication, was the oil level increasing. Link to comment Share on other sites More sharing options...
MarcF Posted June 24, 2013 Author Report Share Posted June 24, 2013 OK, I have replaced the needle of the carbs and if the problem is still there, I will replace the fuel pump. I will be very careful with the oil level (as usual) ... Thanks Link to comment Share on other sites More sharing options...
cdarza Posted August 30, 2013 Report Share Posted August 30, 2013 This has been an issue of mine for years. I would do an oil change and have the correct level. Weeks after, on preflight checks - i would get an above normal oil level reading. After the flight i would sometimes get small amounts of oil streaks on the fuselage and tail. The source always seemed to be the oil vent tube as there was no oil to be found anywhere from the engine. I thought i would be losing enough oil to have a lesser reading. But the readings were always showing normal or above normal during preflights. It appears that as the hours went by to the next oil change (50 Hours) I was gaining oil !! - Am still perplexed by this. Link to comment Share on other sites More sharing options...
Roger Lee Posted August 30, 2013 Report Share Posted August 30, 2013 The oil vent tube is the only breather open to the outside on the engine. It constantly produces vapors, burns off moisture and any small amount of fuel they may get passed through the system. This is normal. many planes have a coating on the bottom of there plane where these vapors vent and yes if the oil is over filled it will vent there too. Many pilots never wipe the bottom of the plane off, but if you use a little de-greaser the rag will be at a minimum yellowed. If you only put in your 3 qts. then that shouldn't happen, but sometimes if you fail to rotate the prop before the oil change and if your engine has the propensity to hold a little more oil in the bottom of the crankcase then you could get a little oil venting from a slight, but not harmful over fill. If your vent tube is in the air stream then it can pull some extra oil out and make a mess. I have seen some take oil samples for their annual analysis and find some traces of fuel which under the right circumstances may be normal and it may be intermittent. Of course if someones rings were shot or broken a little fuel will be in the oil and or it may blow more oil out the vent tube from a little extra pressure going to the oil tank. No I don't think this is your problem, but I thought I would just throw it in. Link to comment Share on other sites More sharing options...
Greg Posted August 31, 2013 Report Share Posted August 31, 2013 Not as mechanical and mechanically experienced as many. But I will try to add some information on fuel in oil. Last February after annual with carburator rebuild ( new needles ?) ( not Roger as he is to far away, but a very good and very experienced CT mechanic who I trust completely) I flew my CTLS 3 1/2 hours home. I failed to close fuel valve. Several days later went to fly. Checked oil and it was way past too full. Called mechanic that did annual. He advised to try to rotate prop and call back. Prop would not rotate. Hydrollic lock. Mechanic advised drain oil. It was full of gas mixed with oil. Strong smell of gas and when poured on asphalt sample mostly evaporated. Per mechanic, drained and changed oil and filter. Motor was then fine. Always close fuel valve since! No problems since. Mechanic advised new needle stuck and let fuel flow from gravity through engine and into oil. I do not know if this makes sense for our engines but it happened to me and keeping the fuel valve closed has become important. Roger - does this make sense? Link to comment Share on other sites More sharing options...
Roger Lee Posted August 31, 2013 Report Share Posted August 31, 2013 Yes it can happen and that's why I tell everyone to close the fuel valve when leaving it for any period of time. As you found out under some very specific circumstance you can get a hydro lock. This is not normal, but things were just right for this to happen like this and you never know. This can happen if the float level is too high, but more importantly your needle valve has to leak and not control the level so if the carb floods with fuel then it can spill out into the air tube or back into the cylinder and fill a cylinder where a valve may be partially open. Close your fuel valves when not in use is the preventative action. Rebuilding the carbs as the hours and years mount is the other. Link to comment Share on other sites More sharing options...
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