For research, i pulled a pa28 181 POH and looked at the cruise information… If read correctly, the POH says to consult the Lycoming ops manual for the engine (o360 series. ) Of course everyone has that correct? In the Lyc ops manual, while they have data for less power settings,, they pretty much consider 65% the lower end “cruise” data point with 75% the upper. Interesting and had not looked at it in a long time. ( i have a 77 172N) I personally run 70% all the time. One more interesting note, Lyc says 140 degrees MIN inlet for oil temp. So they actually specify a number, which i had never seen before. If you do not have the Lyc ops manual, worth getting as technically, the POH at least for this piper, says you have to consult it for ops. The piper POH does give numbers for lower power settings, but other than the Lyc info, no preference as to what you SHOULD use. From a tech standpoint, i would personally recommend 65% as min power for cruise, why? I want the higher temps in the oil system, better combustion scavenge , as well has a higher BMEP in the cylinder to seal rings against the cylinder walls. Less blow by , especially in the long runs.
Sludge, looks like grey clay mud that will build up in hollow crankshafts. Combo mostly of oil deposits and contaminates with bit of lead from fuel. Basically a by product of using the crank as a centrifuge for lack of better description. Can be 1/4 inch or more you have to scrape out. This is why frequent oil changes are important, especially if you have a lot of cylinder blow by. Sludge can also be in the sumps, never drains out all the way on some engines. Not really dangerous, normally seen on hi time or abused engines.
planewrench wrote:
For research, i pulled a pa28 181 POH and looked at the cruise information… If read correctly, the POH says to consult the Lycoming ops manual for the engine (o360 series. )
Well… At least our PA28-181 has a POH with proper power setting diagrams for 55%-75% power.
Of course everyone has that correct?
Actually, yes!
I would also not use that solvent method. It risks damaging the front oil seal, although if done right the stuff should not reach the level of the oil seal.
My experience has been that too many hours of low power flight does bung up the cylinders, though I am not sure whether it is the piston rings, or glazing on cylinder walls, or both. However, it has not happened to me since I originally reported it. I cleared it with high power running.
Some old posts above are disingenuous i.e. the owner didn’t actually do what he posted…
Re bunged up crankshafts, this is one example. The OP never came back but I heard years later that his crankshaft was solidly plugged with some kind of debris. Hard to imagine where it may have come from – there is the filter after all.
