I've read a fair amount of threads where the term 'sumping' has been involved.
I'm in the dark as to what exactly sumping is, and why it seems to be affecting the M8s.
Dry sump ? wet sump ? oil tank below the motor sump ?
Thought i'd just ask y'all
thx

 

During normal operation in a Harley motor, the crank shaft should be spinning in a light oil bath created by flywheels splashing a liitle oil around. When "sumping" occurs, the lower engine case fills with oil, and instead of the crank splashing some oil, the flywheels are immersed in a pool of oil, which creates a lot of drag and thus reduced power.

 

Further to bad's words above, it is normally associated with bikes that have a separate oilbag, located well above the crankcase, such as Sportsters and older bikes like Shovels and early Evos. It is also normally caused by failure of a ball valve in the camchest, which should prevent sumping. I'm mystified that an M8 should suffer from it, as the oil tank is under the transmission. Might be worth visiting the M8 forum, to see what owners are talking about on this subject.

 

I have a curiosity question on this sumping.
Has anyone blown up an engine starting one up that has had all the oil drained into the crankcase?
Looks like it would starve oil from bearings & pistons all the while causing excess crankcase pressures.
Looks to me, would it be best to drain the crankcase and refill the reservoir first before starting it up if this ever happens?

 

Like others have said "sumping" occurs when excessive oil accumulates in the engine's lower end. Harleys use a forced fed system so there should be a minimal amount of oil in the lower end/crankcase

I've heard the term "oil sump" use to describe the M8's 5 qt. system, I think this is causing a bit of confusion as the M8s still use the force fed system. Oil sump = integrated oil tank

 

The m8's sumping issue is different than the old motors. The old motors could leak oil down past a check ball, filling the crankcase with oil when not running, and would make a mess when you would start it up. The M8 fills up while running somehow.

 

that issue is due to hydraulic lock and usually occurs mostly on modified engines where the bag is lower that the c/c. what happens is on long runs with modified c/c venting, the entire system goes to a negative pressure which impedes flow to the bag, with a diff'l in pressure, the oil flows more freely. usually if the throttle is chopped, it goes back to normal but in the meantime, oil pools in the c/c. hd does know of this and does give warning about modified venting.

 

Most all of the new sumping problems happen after the stage upgrades on the m8s motors . I am pretty happy the the way my stock m8 preforms and will wait until some better upgrade come out. It’s the emissions system giving us the problems EPA crap plus your playing your warranty not worth it to me.

 

But how do you detect it? Does the oil level read really high after running it after a normal fill or something? Spew out somewhere?

 

usually a tell is excessive oil out the breathers since the c/c is on a negative pressure so blow-by is reduced and when the c/c returns to normal there is excessive oil in the separation chamber. never seen a hd engine fail with excessive oil in the c/c on start up, of coarse not wise to rev up, but it will mark its spot on older machines. although there is oil pressure, hd is more about flow. one thing on the lower than c/c systems is that never have excessive oil in the bag since if the level covers the balance line that equalizes it to the c/c the bag can hydraulic lock.