I have a 26 with a Texas T large capacity outside oiler. I also have a sight glass installed where the lower oil spigot is on the transmission. It extends up about 1 1/2" above the top oil spigot. I fill the crank case with the engine off till i'm slightly above the top oil spigot. When the engine is running at it's highest RPM, the oil level is half way between the top and bottom spigot. Today, after I got back to the house from a 20 mile trip, I parked at the front of the driveway on level ground to open the garage door and put the top down. As I was walking back from opening the doors, I noticed the truck was smoking pretty good. Engine was running smoothly but smoking. I stuck my head under the truck to see where the smoke was coming from. It was coming from the exhaust. I also noticed no oil in the sight glass while the engine was running. I shut the engine off and coasted the truck into the garage. After turning the light in the shop on, I looked at the oil sight glass again, and the oil was at the normal level, just above the top spigot. I know that I wasn't seeing things. The truck was outside in the sunlight when I checked with the engine running. I started the engine back up and no smoking, oil level was half way between the spigots. I live in central Va. so we have lots of hills. I was driving in a mix of hills and flat ground. I drove about 5 miles on level ground before I got back to the house. What the heck is going on? where did the oil go? Why did it go there? what made it come back? If it was all up in the pan, why wasn't it draining back when I parked? How did it all get in the pan?
My guess is that the sight glass is vented at the top. Any positive pressure on the sight glass will force some oil out, that oil is blowing back on to the exhaust pipe.
One cylinder engines engines develop lots of crank case pressure every revolution as the single piston goes up and down in an enclosed crankcase. I have seen snow blower engines ruined when all the oil was pushed out thru the vent in a sight glass.
Different RPMs affect the visible oil level in the sight glass in a way that is counter intuitive. Also, idling for a bit is a high vacuum situation so could be oil sucked in past the valve guides causing smokey exhaust?
With that much oil in the transmission it's no wonder it smokes.
Don't you get a lot of creep when you start it?
Chester,
There seems to be an inconstancy in your story. You said, "I parked at the front of the driveway on level ground..." And then you said, "I shut the engine off and coasted the truck into the garage."
Sounds to me like it may have been sloping down some to the garage and the oil was ponded in the front of the engine with the extra splashing causing some oil to get by the rings and cause the smoke.
Jim
When you run the engine at a fast pace, the flywheel will splash the oil all around the hogs head and some will run down the oiler to the front of the engine where it will run through the dips and back into the crankcase where the process will be repeated. As the rods dip into the dips in the pan, they will through oil up into the cylinders and inside of the block which will slowly drip back into the pan and run back to the crankcase and be repeated. You say the car had been run fast for 20 miles and apparently it was still running as you put the top down, so the oil really didn't get a chance to run back to the sump. After the engine was turned off and the car sat for a few minutes the oil level in the sump rose and so you saw oil on the sight gauge.
Four things can cause "smoke" 1. Rich fuel mixture will cause black smoke. 2. Excessive oil burning past the rings will cause blue smoke.
3. Oil dripping on hot exhaust system will also cause smoke. 4. Coolant leak into the cylinders will cause white "smoke" which is really steam.
The amount of driving you did was really not enough to make a noticeable change in the oil level even if the car was burning oil. Oil burning is most noticeable when you start out after having stopped on compression, such as giving it gas after descending a long hill with the throttle closed, or starting out from a stop after coming to a slow stop. Coolant "smoke" will be most noticeable when starting the engine after the car has been parked overnight. Rich mixture smoke can occur at any time and it should disappear when you rotate the carburetor adjustment clockwise.
Norm
The site gauge, just like the petcock, is for checking the oil level when the motor is off.
This is no different than checking the oil dipstick on your modern car. You do it when the motor is off.
There's no benefit to over-filling the crankcase of your Model T Ford or any other car for that matter. Over-filling can cause a number of problems.
Sight, not site...
Norm
I believe you should probably add #5 to your list, and that would be what Eric mentioned...that being oil sucked past the intake valves at high vacuum situation.
Many T's will only smoke at idle, and sometimes intermittently and not consistently. I'd be inclined to check the valve chamber drain holes and make sure they're clear. If not, then a bit of oil may accumulate there and be drawn up the intake valves, particularly if the guides are worn (and they usually are).
Could it be that you have a screen in your transmission cover and it is clogged? That might trap a lot of oil atop the screen when running, and let it drip back down when the engine stops. Just a thought.
I agree with Scott. It is not as significant as in overhead valve cars with oil flowing over the valve heads, however.
Norm