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Some info about Onan twins:
The static (engine not running) engine oil level is above the bottom of the dip stick tube. As the engine cools, the air above the oil in the dipstick tube contracts drawing oil up into the tube. This is particularly on Onan P series engines but not limited to them. Onan P series engines, 16, 18, and 20 HP models with the standard oil base will take 3 pints of engine oil in an oil change where the oil filter is not replaced and more if the filter is changed.
The lubrication system on aluminum block Onan twins provides oil under pressure to both crankshaft bearings, both connecting rod bearings and the front camshaft bearing. The rear camshaft bearing and the tappets are lubricated by splashing oil when the engine is running. Running these engines at low engine oil levels causes less or no oil to get splashed onto the rear camshaft bearing and tappets. In time the rear camshaft bearing wears into an oval shape. As this bearing continues to wear, the camshaft moves from side to side as the engine is running and makes a ticking noise. As the camshaft turns, it is moved from side to side by the force of the valve springs.
If during a valve adjustment, it is noted that the adjustment in not repeatable, then the rear camshaft bearing is worn excessively. Onan has an upgraded bearing replacement for this bearing, however replacing it is involves a major tear down of the engine during which other areas of the engine may also need to be addressed. :cool:
 

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Hi joe baring,
Your pic of the engine data plate is missing the most important part which is the 5 digit spec number beginning with 109, if it is an I/10936G, then it is an Onan P218 setup as a replacement for the B48M that was originally in the 448. A potential problem that I see in your pics is the aftermarket oil filter, some of which can leak down and cause incorrect oil level readings. :cool:
 
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