----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----At 02:20 PM 12/12/2005, Donald Perricone wrote:
A few days later we tried to fly again and the same problem came back. This time we didn't have time to run it and try to burn out the fouled plug.
How much time did you plan on spending doing this? 30 seconds ought to do it unless it's not oil related.
The compression check found every cylinder in the high 70s over 80 which was good news.
Actually, this doesn't mean as much as it seems at first glance. Oil leaking by the rings actually helps seal the cylinder and increase the readings.
Does anyone have any ideas about how ot solve this problem. We would like to hear from anyone who might have some suggestions.
Are you using AvGas? Could the problem be lead related? Lead is a lot harder to "burn off" than oil.
Try pulling the lower plugs before disturbing the engine after it has been sitting since the previous flight. Look for oil in any of the cylinders. If you find oil in one or more cylinders, see if there is a correlation between the oily cylinder and an open intake valve. (don't move the prop before completing this task!) If there is, your problem may be the same as previously described in "RE: Rocker Arms".
Just to set the rocker arm record straight, there are no "new style" rockers. The exhaust valve rockers have always had oil spray holes. The intakes originally did not and are a separate part. Continental has approved use of the exhaust rocker on the intake side, and many overhaul shops and cylinder shops routinely supply the same rocker for both. If your intake valve to guide clearance is not good and tight, the oil runs down the valve stem and either into the intake tract or cylinder, depending on the position of the valve when at rest. You may get as much as a teaspoon of oil in a cylinder, most of which ends up in the plug well. The simple solution is to install the rockers without the oil spray holes.
You said that at one point the problem recurred on the right mag. Is it still firing the correct (top) plugs, or are the wires switched around? If the upper plugs are fouling I'd suspect a problem plug. If it's always the lower ones, I'd suspect oil in the cylinders. If it's oil, 20 or 30 seconds of full throttle on both mags ought to clear it up
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