Is this wet sumping?

My '74 Roadster is new to me. I've ridden it only since April. After a long ride last Sunday I checked the dipstick and the oil level was way down. On Tuesday I drained the sump to see if that's where the oil went. Is eight ounces normal?

Immediately after a long ride, the oil level should appear on the dipstick near the upper level mark.

8 ounces in the sump seems a bit much, but not excessive.

After a ride you should have almost no oil in the sump because the oil pump is sucking it out of there. Eight oounces isn't too much though as oil runs down from the head and back down the return hose and from elsewhere.

Wet sumping happens when oil leaks down from the oil tank, through the oil pump, and then into the crankcase.
We gripe about it because it causes a lot of oil burning/smoke at startup and because, if the bike is not run for a extended period then the crankcase may even fill up with oil, leaving an empty oil tank, and even, though I've never seen it, hydraulic locking the engine.

Overall, the problem is overstated. For me, I always push the engine through a few strokes before I turn the key on just to make sure and to start the evacuation of any oil that might be in the crankcase; I always get a little smoke on start up because of some oil inevitably leaks down. So what? The smoke clears in a moment and I know that the bores and cam shaft and timing chest all got a good splash on start up.

Wet sumping depends on many factors. What grade oil are you using? The thinner it is the faster it will find it's way past the oil pump into the sump. Also it's best to turn the engine over onto compression so pistons are near Top Dead Centre as that slows down the flow into the sump. Only time to accurately check the oil level is immediately after stopping the engine.

Ian

"True" "wet sumping" is what the scavenge can't keep up with the flow. This was an issue with the 72 cases under higher then normal rpm ranges. The other situation is when oil leaks back through a worn pump when sitting. Some times it's day, sometimes it's weeks.

I have found that if you come in from a ride and shut the down without though of draining the sump by letting it run for a while, then you will generally have 5 to 7 oz, maybe even 8oz from normal rundown and drainage from the timing chest which can hold a few oz's on its own.

For this reason it maybe a good idea to shut it right down to insure that at least 5 to 7oz of oil is in the sump before starting.

Also, when filling the system with oil, lay off just a bit, run it till warm, then check and bring to the line. There is some grace there.

From one Pete to another, I would use the recommended 20W-50W motor oil and periodically check the dipstick to visually ascertain that the level is about halfway ,not to the high mark at all. I'm opening myself up to dissention on this point but I have my reasons. How many miles on the 828 ,B.T.W, as 8 oz. only seems a tad too much to drain out of the sump ,mileage is a wear factor to any pump. Some fools put an inline valve to stop greater sumping , add me to the list of clown jesters.

Thank you guys. I appreciate your helpful input. I have good quality 20W-50 in the motor. (Kendell Titanium GT-1 20W-50). There are 22,000 miles on the odometer. Now that I know that there's some wet sumping occuring, I won't reflexively top it up with oil. Thanks for the the suggestion to check the dipstick immediately after turning off the motor. I thought the correct procedure was to wait at least ten - fifteen minutes before checking.

Pete_B said:

Thank you guys. I appreciate your helpful input. I have good quality 20W-50 in the motor. (Kendell Titanium GT-1 20W-50). There are 22,000 miles on the odometer. Now that I know that there's some wet sumping occuring, I won't reflexively top it up with oil. Thanks for the the suggestion to check the dipstick immediately after turning off the motor. I thought the correct procedure was to wait at least ten - fifteen minutes before checking.

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After shutting off the motor, there is no more oil going to the tank so that level will not change. Now if you let the motor run a minute or so before shutting down, you will get some of the sump oil to return to the tank to get a more accurate oil level.
As mentioned before, there is some flexibility/grace there. When you measure when filling after an oil change, is when we really know how much is in there. After that it's sort of a common sense thing realizing that there is some other oil in the system somewhere, sump, filter, timing chest etc.