Need "Oil Pump for Dummies" info

[Jazzy Pappy]

Need "Oil pump for Dummies" info. Clymers and HD doesn't explain in detail. My 65 has the pump with the side check valve and top check ball. What's the purpose of these? I'm pretty sure about the outlets for chain oilers and the supply inlet from the oil tank but the two return lines from pump to oil tank? Why two? and does it matter which oil tank inlet they are hooked to? I am trying to gain understanding of the oil circuit so I can figure out why I seem to have too much crankcase pressure. Where does the crankcase vent? My gauge shows 60# cold 20-25 hot. I just replaced seals and did a ring job, checked the valves, guides, etc. Don't want to chance damaging seals with too much crankcase pressure. Is there an easy way to check for too much pressure?
OK guys tell me how the cow ate the cabbage!
JP

[51Hog]

I do not know about the 65 model, but every engine that I have ever worked on with the exception of a 2 stroke, Has a Crank Case Vent. If your engine is vented properly and the vent is not plugged, you should not have any measurable Crank Case Pressure----
Are you talking about CC Pressure or Oil pressure
Check pages 90, 96 and 97 of the 48-57 Panhead Service manual. The pumps should work about the same.
The book says 30 lbs for hot oil---
Dale

[awander]

Yeah, Jazzy:

There should be only 2 oil lines from the tank to the pump
-one is the feed line and connects from the rear of the tanlk to the bottom of teh pump
-the other is the return line and connects near the top of the pump, and goes to one of the tank connections at the top.

The other line goes from the engine case to the other top tank connection-this is the crankcase vent line.

Functionally, it shouldn't matter which top tank connection the return and vent lines go to-unless your tank is one of the ones with an internal filter-then it might matter.

[Cotten]

JP!

If your machine is the way the Factory intended, you have three lines from the tank: Feed from the bottom of the tank to the bottom of the pump, a return from the pump to the filter chamber, and a breather line from the top of the tank into the motorcase above the pump.

The purpose of the ball checks are to prevent the oiltank from emptying itself while sitting parked, and to bleed off excess pressure into the gearcase when too cold.

The best thing to do with an oil pressure gauge is to put it back on the shelf.

....Cotten

[hogboy52]

The CC vent exit is into the primary chain cover. When turning the engine over slowly there should be a definite whoosh of air through this tube once each cycle if it hasn't been somehow plugged or capped off. The crankcase breather valve in the timing case cover must also be aligned correctly.