What is sumping and how can you tell if it's going on?? I never had a problem with oil blow by dripping out of the breather but now I do. When I changed engine oil only got about 2.5 quarts out and the dip stick read full before I drained it.

 

The crankcase holds half a quart.

 

A common symptom is a loss of horsepower. When the oil pump doesn't pull enough oil out of the bottom end the fly-wheel has to spin in the excess oil. It slows things down and makes it sluggish. If you pull the case freeze plug underneath and you have more than 6oz of oil, it's sumping. 6oz is on the higher side, but generally still considered acceptable.

 

sumping occurs most often on bikes with the oil tank ABOVE the motor- touring before 1993, softails, FXRs etc.

there is a check ball in the old style oil pump which, if the seat was worn, spring weak or left sitting long time) would allow oil to seep into the crankcase.

on start up all that oil would come out the breather which pre- 1993 was at the oil pump (not the heads- the head breather started in 1993)

so that is sumping.

when changing oil, do it hot, that way everything bad is in suspension and will be washed out with the old oil ( a residual amount will remain in the motor during the change- no big deal) the warm oil flows better out of the motor too.

we are in good shape in that with our oil tank BELOW the engine, we do get pretty good draining- I have other old bikes where I have to wash out the oil tank with kerosene every few changes.

dip stick- read as to manual, hot on jiffy stand?
that probably doesn;t matter.


---------- a HUGE contributor to oil blow by is a full oil tank, pressure ( from the piston going up and down) builds and pushes some oil where you don't want it.

Many of us run out oil levels down 1 pint from full- that decreases breather blow by into the air cleaner.

Breather valves can wear out, but I've never had it happen to me.

some guys throw a maxi pad into the air cleaner cover ( on the bottom) to pick up and hold stray oil ( change every 28 days)

also too high oil level can push your dipstick out and cover the rear of you bike with foamy oil--- like when accelerating hard onto a freeway ramp.

So, before we worry too much, check your oil level.

mike

 

Thanks for the info guy's!

 

I talked with the Harley rep at the factory about oil blowing out of the AC. He I should only fill the oil up half way, no more or it will blow out the AC.

 

I have to call BS on the "run it a half quart low" to avoid puking oil out the air cleaner. The maufacturer specifies the amount of lubricant required for the engine and the dealer throws all that under the bus and tells the owner to disregard the manufacturer's specifications; come on guys, how lame is that. If you have oil coming out the air cleaner, there is a reason for it; oil pump is not aligned, engine is sumping, crankcase breathers restricted, oil getting by rings, etc., but not because crankcase was filled per the manufacturer's recomendation/specification.

Sumping is not limited to bikes with oil tanks above the crankcase; it is fairly common to the "A" engines with the crankcase under the transmission. A pinched or wrong o-ring to seal the connection between the scavenge side of the oil pump to the crankcase at the scavenge port or a mis-aligned oil pump can both cause sumping. It is simply a condition wherein the oil pump is not removing oil from the crank case as fast as it should. As Dawg says, the crank wheels then must rotate in an oil bath. Look at it like this, it's like trying to run in waist deep water.

Symptoms are sluggish performance and the engine will heat up quick and run hot. The oil not only lubricates but is also a coolant.

The way to check for sumping is to ride the bike, get the engine up to operating temps and then, per Dawg's post, pull the crank case drain plug and see how much oil comes out. I have seen nearly a quart come out of a sumping engine but 4-6 ounces is normal. Be careful R/Ring the crankcase drain plug. It's an NPT plug and being tapered can crack a case if over tightened.

 

Just to check: the guy at the dealership should have meant no more than halfway between ADD and FULL on the dipstick, not half of the oil specified in the motor.

If he meant only half in the motor, then he is wrong and you risk engine damage.

 

Where on the CC is the drain (freeze plug) located? I think I will remove it and see what comes out.

 

Look underneath the bike directly below the crankshaft. Another symptom of sumping is overheated oil, so if you experience high oil temperatures and sluggish performance after the bike warms up, you may have a problem. I've never experienced it but understand it is most-commonly caused by pinched or misplaced o-rings in the cam-chest.