This article will discuss the repair of the oil pump of a chainsaw. Many owners have encountered such a phenomenon as the lack of oil supply to lubricate the chain or its leakage in the wrong place. Let us analyze the causes of these phenomena and methods of elimination.
How is the oil pump arranged?
The oil feed pump is located on the crankcase, on the same side as the drive. right behind the drive sprocket. To understand how it works, you need to look at the images and see what parts it consists of and what moves where.
So, this is what the oil pump looks like (it may look different for different models, but there is one principle).
And here is his working scheme.
It all works like that.
From the drive through the worm gear rotation is transmitted to the plunger, which, rotating, makes a longitudinal reciprocating motion. This back and forth movement is ensured by the shape of the plunger, an adjusting screw with an eccentric and a thrust spring. When the plunger moves back, the oil is sucked into the oil chamber through the inlet due to the created vacuum (similar to a syringe). When moving forward, oil is pushed through the outlet of the oil chamber. To ensure tightness, a rubber cuff is used (it is not shown in the diagram).
To prevent both holes from being opened at the same time, there is a segment cutout at the end of the plunger. When moving back, it is turned to the inlet, while the outlet is closed. When moving forward, the inlet closes and the outlet opens, since the segment cut-out rotates toward the outlet. Thus, in one revolution, the plunger makes one reciprocating motion.
To reduce or increase the stroke of the plunger, an adjusting screw with an eccentric is used. The eccentric in this case is a cylinder built into the body of the adjusting screw. In this case, the central axis of this cylinder does not coincide with the axis of rotation of the screw, therefore, if the screw is rotated, then the cylinder either approaches the end of the plunger, then moves away from it. Actually this is the essence of the eccentric. Because of this displacement relative to the center, it is often called a cam.
Video: Does Not Pump The Oil Pump On A Chainsaw
At maximum approximation, the plunger will not have a stroke, and the oil will not swing. At maximum distance, on the contrary, the plunger will have a maximum stroke, which means that it will pump oil to the maximum.
But how does the plunger go back and forth? Everything is simple. Its end face is processed in such a way that in the middle it has a central protrusion, which abuts against the eccentric, and the end edge is made in the form of a ring around this central protrusion. At the same time, the ring is not perpendicular to the longitudinal axis of the plunger, but is at a certain angle, forming a bevel. one part turns out to stick out a little. The adjusting screw and the end face of the plunger are aligned so that the edge of the end face during rotation is in contact with the screw, either the protruding part or the non-unlocking part. When touching protruding. the plunger moves forward. When non-engaging. back. In this case, the plunger moves back due to the thrust spring.
Faults, causes and remedies
What are the malfunctions, we already noted at the beginning. either the oil is not supplied, or leaks where it is not necessary. How to fix it?
No oil
The lack of oil supply, if at the same time it does not leak anywhere, is due to the lack of stroke on the plunger. This may be due to improper installation of the adjusting screw, or due to wear of the plunger itself.
The adjusting screw may not stand properly if you or someone else previously disassembled the oil pump and assembled it incorrectly. In this case, the / marks are correct, but the screw is set to the opposite position. In this case, disassemble the pump and set the screw correctly. Or simply turn the screw closer to “-“. The screw itself, as a rule, does not spontaneously stand in a position blocking the plunger stroke.
The wear of the plunger consists in the fact that the edge of its end has been sharpened so that it does not have a protruding part, but instead the entire edge is in the same plane. In this case, if you do not want to buy spare parts, you can grind the edge of the end face of the plunger, giving it its original shape. in this case, you must not forget and undermine the central protrusion. After such turning, the volume of the oil chamber will increase slightly, as the plunger will move back a little. But it will be pumping nonetheless.
If the pump does not pump, but at the same time oil flows from the chainsaw body, then most likely one of the hoses has been disconnected. either inlet or outlet. If the input, then the oil will flow and not wound saw. If the day off, then it will pour only on an established chainsaw. It’s clear that to fix this problem you just need to put the hoses back on.
Oil is leaking
We examined one of the causes of smudges a little higher, although it is not connected with a malfunction of the oil pump itself. But it happens that a chainsaw works, and even oil is supplied, but at the same time, oil also flows from the case.
This happens if the oil flows through the rubber seal. It may wear out, or was previously incorrectly installed by someone.
Also, along with cuff wear, wear on the walls of the oil pump cylinder itself can occur. In this case, it will be necessary to change the entire pump as a whole, since it is unlikely that it will be possible to find just the pump body without all the other parts.
These are the malfunctions of the chainsaw oil pump and how to eliminate them. I hope the article helped you sort this out.