I think the unique thing about the crank is the high centrifugal load that probably slings the sludge out rather than keeping it in suspension.
I guess we are talking about the alternator belt then, right?
As a side note, I see you have ordered a
S-21. I have wings & tail feathers done on mine,starting on fuselage now.
I seem to recall a recommendation of 500 hrs somewhere in Lycoming literatature, but I can't remember where. I could be imagining it.
I didn't know anything about the sludge at 300 hrs when my prop came off to re-seal it. OMG, I thought. So I read up on it, and I think that is where I came across it.
One of the thoughts I had was, YUK! If there is sludge here, what about elsewhere? I think the unique thing about the crank is the high centrifugal load that probably slings the sludge out rather than keeping it in suspension.
My other thought was, "this is engine oil. The only exposure to lead would be from blow-by during combustion. How is there so much?"
Back in the days of leaded fuel for cars, I used to find similar grey sludge deposited in various parts of the engine. Getting rid of this will be a nice side-benefit when they eliminate lead from our avgas.
I am not aware of ANY requirement or written recommendation from the manufacturer for cleaning sludge out of the crankshaft between overhauls.
Please provide a link to the document or written recommendation.
At 500-600 hrs there may be some sludge in the crank bore. Some engines will have a lot. I think that is a reasonable interval to take a look.
Don Broussard
RV9 Rebuild in Progress
57 Pacer
Look in your Hartzell manual for the recomendation to clean the sludge.
I cycle my prop a couple of times before shutting down. This replaces the sludge with clean oil. This was a suggestion from the war birds on the field.
Curious why?
Where is there sludge? Or why take a look?
Don?t know what causes it to form, but probably connected to the amount of blowby, how rich you run, how often you fly, the fuel you use and operating oil temp. Oil type may play a part as well but I have no data. I can only say that if I get into a fixed pitch engine with 500 or more hrs run time the crank bore will likely have a layer of sludge coating the bore. Over time combustion causes solid particles to form in the oil and the crank does a good job as a centrifical separator. This sludge is very dense and does not scrape out easily. Rust can form under the sludge layer. I like the 500hr/4 year interval to clean it out and make sure rust is not happening. A rust pit beyond a certain depth will scrap the crank. PID coating certainly helps with rust prevention.
Don Broussard
RV9 Rebuild in Progress
57 Pacer
Lycoming has an AD or SB for cleaning sludge at five yrs on engines with hollow CS. You have to remove the plug, clean and replace with a new plug.
Lycoming has an AD or SB for cleaning sludge at five yrs on engines with hollow CS. You have to remove the plug, clean and replace with a new plug.
To decrappify the crank after a constant-speed prop is removed lift the tail of the aircraft so there is a downward slope of the crank so the cwap can run out. Get about 4 cans of starting fluid and a long narrow brush or shotgun cleaning rod. Place a bucket under the crank opening to catch the cwap. Squirt starting fluid into the crank to flush it and use the long brush to dislodge the tougher cwap. It is amazing what comes out even with a 200 hour engine.
Jim
Show me.
The AD is not for cleaning the sludge.
Thanks for all the replies.
I like this method. Thanks Jim. Will be on my list at annual.
There is NOTHING in the Hartzell Prop Owner's Manual 115N about removing the prop and cleaning the crankshaft.
Please show me where this information is located.
Old Honda motorcycle engines used to have a "can" bolted to the end of the crank, just for this purpose.
Worked quite well, but needed regular service/cleaning.
Imagine what our engines would have in the crank if we did not also have a real oil filter??