Oil Reservoir Tank Fill at the Top Read It

The fill cap is on top, and the body is translucent, so a quick look tells you if the oil is there. That is the whole job of this small oil reservoir tank.

What does the little tank do on a machine? It is an auxiliary reservoir, holding oil at hand on the machine so you do not go back and forth for a bottle. The body carries two molded marks, UPPER and LOWER, the upper one the fill line and the lower one the minimum, and a level between the two is normal, below the lower one means it is time to top up. The body is translucent, so without opening the cap, a look against the light shows where the line sits, and you know where you stand.

Why is the body translucent? A fuel tank has two things to fear, being overfilled and running dry. Overfill and it weeps out of the mouth, run dry and the machine starves. A solid body hides both, and finding out means opening the cap, which is how fuel gets spilled. A translucent body puts the line on the outside, the two marks doing the reading, and enough or full becomes a glance.

Why a twist cap? The fill mouth is on top, and the cap twists on, so the machine running over the road does not slosh the oil out, and road dust does not get in. Open the cap and look, the mouth and the shoulder of the tank carry a lip, so when a bottle is poured in, the oil does not run down the outside.

What is the ear on the side for? The tank cannot hang loose; it has to be fixed to the machine. The ear on the side carries a locating hole, lining up with a stud or hook on the machine, holding the tank steady so it does not swing or tip when you fill it. Which way the ear faces decides which side of the machine the tank sits on.

What is the port at the bottom for? The oil leaves through the port at the bottom, into a hose or onto the machine's fill point. The port being at the bottom means the tank drains clean, with no column of oil left standing at the base.

When to replace it? The body yellows and fogs so the marks can no longer be read, the cap will not hold, the ear is cracked, or the bottom port weeps, then swap the whole tank. The seal ring rides with the cap, and an old ring that has hardened and weeps comes new with the new tank.

What to check when fitting it? Line up the ear hole, the direction of the bottom port, and the cap diameter on the new tank against the old one. Machines of the same type mostly fit, but fit is not guaranteed for every one, so comparing against the old part is the safe way. Hang it on, add a little oil, give it a shake and check for weeping, then put it to work.