MF 40 Oil Pump

[docrocky]

I recently obtained this tractor from a good friend of mine. It has a front end loader which makes access to the engine oil intake cumbersome. I had to feed a funnel from the top of the lift arm. In so doing when I was finished I failed to put the oil stopper cap (black rubber plug) into the intake. (I will provide photos of what I aam describing since I don't have the terminology of the parts). I then proceeded to disc about 2 acres of saandy loam which was fairly dry. On my last pass the engine started stalling out. I though I was low on fuel, but it was ok. Oil pressure seemed ok (quick glances) and the temp gauge remained mid was in the green. As I tried to start it , it hardly wanted to turn over. I was able to get it back to the barn which was about 300 feet away. After parking it a few minutes, it wouldn't turn over. At this point I found the oil cap in my pocket. The oil level was ok on dip stick check and the engine was not over heated. I then waited about a hour and she turned over easier and started but then there was a distinct knocking. I quickly turned it off.

Question: How does the oil pump function in this model and by running it with the cap off, was there a problem of no vacuum and did I do internal damage to the valves/pistons etc.

 

[Harry in Ky]

Sandy, eh? Can't think of a better additive to motor oil for chewing up bearings. Your photo clearly shows the close proximity of the filler opening to the fan blade. With a steady flow of dusty grit being pulled through the radiator and past the opening, it's hard to imagine at least some of that not making it's way down the open hole. At this point, I would definitely drain the oil and examine it carefully. rub a sample between your fingers to see what it feels like. If you notice anything rough, gritty or any texture other than slick oil, you can assume it's done some bearing damage by now.

 

[Jerry/MT]

Generally speaking the sump in an IC engine is slightly pressurized by blow by gasses so it's not like there is suction on filler neck opening to suck in dust. While there might be some dust that got in I would doubt that a couple of hours of disking did in an otherwise good engine. By all means drain the oil and look for dirt or metallic debris in the oil. Your oil is filtered but some of these old machines used partial flow filters so you can't count on the lube oil being filtered before getting to the bearings.
It's also possible you had a failure unrelated to the oil cap being off. If your going to drain the oil, drop the pan look for damage.