Burp oil before leakdown test???

Kevin I agree that if there was a problem that it would be apparent. I see this as a thought exercise and also an attempt to remain consistent with the results year after year. Last year even with good numbers I heard the oil gurgling while testing. It wasn’t during the first cylinder so I guess it was pushing oil up until that point and then air afterwards. I didn’t start over to see if it made a difference but I did make a note to burp beforehand next time. 

Sam with a leakdown test if there is any back pressure buildup in the crankcase it would affect the numbers. I suppose as quickly as the test goes that there may not be sufficient time to develop significant pressure though. 

Norman Hanchey wrote:

Thanks Roger. I always value your replies and experience here. However I'm failing to see the connection between a hot/cold engine and one with oil remaining in the crankcase and oil return line to the tank.

Hi Norman,

You're right I did get off topic. I should have read better.

The oil in the bottom of the crankcase shouldn't make any difference. You're measuring leaks of air up at the cylinder. You can hear sometimes air gurgling inside the tank.

There is no crankcase pressure because it’s always vented back to the oil tank. That’s how a dry sump works. So why bother burping when it’s going to burp itself with the ring blow by anyway during a compression check.

Sam Purpura wrote:

There is no crankcase pressure because it’s always vented back to the oil tank. That’s how a dry sump works. So why bother burping when it’s going to burp itself with the ring blow by anyway during a compression check.

Crankcase pressure is required to return the oil to the tank. I was asking if it would be enough to skew the results of the test.