Oil checking

[Al Downs]

When is the proper time to check the oil level? Before or after burping? Should you burp the engine everytime before start up or only first start up?

[Ed Cesnalis]

Why get all hung up on burping your CT? If I see adequate oil I'm good to go because I already know I'm not overfull.

 

If I want to turn my prop prior to start up I do. If I want to get the most precise oil level reading then I bother to burp.

[FlyingMonkey]

That's the first time I have heard a suggestion *not* to burp before the first flight of the day...tell me more! What would you consider and "adequate oil" indication in an un-burped engine, CT?

[Ed Cesnalis]

Right now my oil level without burping is on the flat part of my

That's the first time I have heard a suggestion *not* to burp before the first flight of the day...tell me more! What would you consider and "adequate oil" indication in an un-burped engine, CT?

 

Adequate oil would be at min or above.

[sandpiper]

If it is at min. or above you know you have enough because burping will increase the reading. If the plane is a rental I would be more likely to burp. But, with my own, usually in a secure hangar, if there is no oil on the floor and the belly is still clean, and a pre-burp reading is on the flat spot of the stick, then the oil is OK.

[FlyingMonkey]

Cool, thanks!

[Znurtdog]

I like to check the level, THEN burp, check again. That way if I need/want to check without burping, I have an idea of what the level should be. I do think I remember that burping also helps eliminate any air-lock type troubles..?

[sandpiper]

To be 100% technically correct you would burp every time. As for air lock, I don't know what/how that would be. I know that in radials and inverted engines like the ranger, you need to rotate the prop to check for hydraulic lock, caused by oil draining to and accumulating in the low point of cylinders. If started with that condition, you could bend rods.

 

In 30 years of flying the R-985 radial I never experienced that but I always pulled the prop thru several revolutions. I don't see that happening in horizontally opposed engines.

[FastEddieB]

As I've said before, I burp and check AFTER every flight.

 

My plane is in a hangar, and I'm the only one flying it, so I'm comfortable with it.

 

It just takes far less "blades" to get the burp within maybe 10 minutes of shutting down.

 

Works for me.

[Al Downs]

I don't understand why you would burp after a flight. What does that tell you?

[Ed Cesnalis]

It would tell you that ~all off the oil has been returned to the oil tank.

[FastEddieB]

What he said!

[Al Downs]

Am I missing something? You shut off the engine and then burp? I don't see the purpose.

[Ed Cesnalis]

Burping is a process that moves oil remaining in the crankcase to oil tank so that you can measure the oil more accurately. Some like Eddie choose to check their oil after flights instead of before so they can burp with less effort.

 

The purpose of burping is the same before or after.

[sandpiper]

Eddie can do that because he is the only pilot and his plane is in a secure hangar. So, unless he comes back and finds oil all over the floor, he knows the oil is good.

 

If the plane was used by others and/or not in secure storage, then he might do it differently.

 

Also, if he does it post flight, he won't be delayed on his next flight to fix an oil problem. He already knows that oil issues won't be delaying the flight - unless he walks in and finds oil all over the floor.

[Al Downs]

Thanks, I get it.

[Tip]

Several members have found the oil tank over full due to gas in the oil. Fast Eddie's method may miss this condition.

[Al Downs]

How does that much gas get into the oil? If oil is being changed at 50 hours, that seems to be a serious problem.

[FastEddieB]

Several members have found the oil tank over full due to gas in the oil. Fast Eddie's method may miss this condition.

 

Please clarify.

 

How would gas get into the oil as a plane sits in a hangar?

 

Note: my oil tank is above my gas tank. But I'm also having trouble visualizing it from gravity feeding from wing tanks as well - if the BING float bowls overfilled from a stuck needle valve they should just vent to the drip trays and hence to the ground.

 

Right?

[Roger Lee]

Hi Eddie,

 

Sorry not quite. Fuel has migrated to the oil tank just like oil has migrated to the cylinders. This was more prevalent many years ago and that's why we have some of our hold over ideas like checking for hydra lock by turning the prop before flight. The old carb needle valve's and old oil filters had a major play in the issue and people didn't mount the oil tanks within installation specs.

These problems are usually in a high wing and when people don't turn off their fuel the possibility exist that fuel can leak past the needle valve into the carb throat and past the the cyl. valve into the cyl. Not very likely any more, but not impossible. With the old oil filters and with an oil tank mounted too high it could get back into the cyl and if the tank was too low could siphone oil back into the tank. Not likely with the newer filters any more either.

If fuel does drain back to a cyl. and sit for a while it can get past the rings and down into the case with the oil.

I have seen several oil analysis come back with fuel in the oil. It isn't a big deal and we just tell people to keep an eye on things. It is usually self limiting and goes away. The hot oil will boil off the fuel.

[GlennM]

In the old days before multigrade oils, you could deliberately add fuel to the oil to thin it prior to starting on cold days. I seem to remember it mentioned in my Cessna 172 manual, although I could be confused. The fuel would boil off during the flight. I live in Florida so I never did it. That is why the fuel in the oil is not troubling to me in certain instances. If it is in our engines, I would look for the cause, since it does not mention thinning with fuel in the manual. LOL.

[FastEddieB]

Thanks, Roger.

 

With my oil tank and engine both above the fuel tank, I seem to have nothing to worry about - the fuel will hardly flow uphill to get into the engine or oil tank.

 

As an anecdote, I had an opposed twin BMW motorcycle fall over and lay on its side for a few days. When I went to kick it over, it was as if the engine were welded solid.

 

Sure enough, the "downhill" cylinder was full of oil, which shot out of the spark plug hole once the plug was removed. If it had been an electric start model, I guess some real damage could have been done.

 

Then again, those opposed twins are routinely parked on sidestands with one cylinder quite low and lower than the fuel tank, and they now have virtually identical BING's. Worst result is usually a bit of smoke on startup from oil that may have gotten past the rings. No major problems with fuel in the oil or hydraulic lock that I recall reports of.

[sandpiper]

In the old days before multigrade oils, you could deliberately add fuel to the oil to thin it prior to starting on cold days. I seem to remember it mentioned in my Cessna 172 manual, although I could be confused. The fuel would boil off during the flight. I live in Florida so I never did it. That is why the fuel in the oil is not troubling to me in certain instances. If it is in our engines, I would look for the cause, since it does not mention thinning with fuel in the manual. LOL.

 

Glenn,

 

I flew Beavers in Alaska for years. All were military surplus and all were built with a system where the pilot could flip a switch and put fuel into the oil. I think usually done just before shut down. All of these systems were disconnected long before I started flying them (1972). These systems were probably OK in the days before more readily available heat and power sources. Maybe the difference between going or being stranded.

 

By the old days you probably mean before the 1970's. I never ran across anyone who did this but I did run across many who drained their oil after flying then brought it inside at night. By the time I started owning airplanes I always used multi grade but even then I would pre-heat starting about +30F. Not that the engine wouldn't start, just that it increased engine life.

[GlennM]

I have only been flying since 1988, but early in my flying career I could only afford older airplanes. I had a 1959 172 that I am pretty sure mentioned the same thing you described. Now that you mention round engines, it may have been on the Stearman I used to fly. I can't remember. There were quite a few systems that were developed in aviation, but not used very often or were replaced by better methods. I flew a really early Bonanza that had flares that you could deploy over the airport for a night landing. They would shoot out the passenger side near the tail. I never did that, either.

[sandpiper]

I'd bet on the Stearman for oil dilution.

 

Now about those flares. That would come in handy on occasion.