How a chainsaw oil pump works

How it works and how to maintain it

Inspirations / How to

21/10/2020

Estimated reading time 5 minutes

Whether it's a basic or professional model, a chainsaw needs oil and proper lubrication of the guide bar/chain assembly in order to work. This applies whatever the machine’s power source: electric, battery or petrol. The oil minimises friction between the guide bar and chain, enabling the chain to move more smoothly. In practice, proper oiling extends the service life of the cutting system.

Today we talk about the oil pump, an essential component of the chainsaw, describing its circuit and how it works, before explaining how to perform maintenance on it.

Lubricating the chain and guide bar

As you know, the chain is the cutting edge of a chainsaw and is made up of teeth (or “cutters”) and links that run along the guide bar groove. The drive links advance inside the groove, pulling the teeth and joining links of the chain along with them.

As we mentioned, lubrication minimises friction between the guide bar groove and the drive links of the chain. Friction between the moving parts causes them to wear down and overheat, so the oil provides anti-seize and anti-wear protection. It is important to use high-quality chain oil, never waste oil, recycled oil or engine oil. For example, Oleo-Mac stocks Chain Lube biodegradable bar and chain protector, which is formulated with a balanced blend of oils that does not thicken at low temperatures.

The cutting process wears down the chainsaw guide bar, especially at the most stressed points, which are the lower edge and the tip. We suggest you flip your guide bar over periodically so that both sides wear out evenly. When the guide bar groove is very worn, it must be replaced: make sure that the groove depth is not reduced so much that the drive links scrape against the base of the groove.

Although wear is a normal consequence of using a chainsaw, poor lubrication can cause both uneven wear of the groove and brittleness of the metal guide bar due to overheating. In the latter case, if the metal of the guide bar turns blue, this is a clear indication that you need to replace it.

How a chainsaw oil pump works

The oil pump is part of the chainsaw lubrication system, which consists of:

  • Piston pump.

  • Tank with vent, to balance the inside and outside pressure, and a filter that traps impurities.

  • Oil outlet hole on the guide bar.

But how does a chainsaw oil pump work? The crankshaft drives the pump, which draws oil from the tank and pushes it onto the guide bar via the outlet hole. The movement of the chain then distributes the oil along the entire length of the guide bar.

Oil pumps dispense lubricant in different ways, and the oil flow can be:

  • Fixed flow, if the lubricant is pumped at a constant rate.

  • Zero flow when idling: in this case the pump is connected to the clutch coupling and only operates when the chain rotates.

  • Adjustable by means of an adjuster screw, which enables the oil dosage to be set based on the length of the guide bar, the wood being cut and the season.

For example, among the various models in the catalogue, the Oleo-Mac GSH 400 basic chainsaw, GS 451 medium-powered chainsaw and GS 651 professional model are equipped with an automatic oil pump that is calibrated to guarantee adequate lubrication in all working conditions, but which is also adjustable according to your needs, and dispenses no oil when idling.

To ensure a well-oiled guide bar and chain, make sure the tank is full of fresh, good-quality lubricant and regularly clean the chainsaw’s oil pump. But before cleaning it, check whether the chainsaw oil pump is working properly first. Simply point the chainsaw guide bar down towards a dry, uniform surface, and throttle to medium speed for a few seconds. If everything is in order, you will see a stream of tiny oil droplets fall to the ground from the moving chain.

How to clean a chainsaw oil pump

Did your chainsaw fail the lubrication test? It might just be a cleanliness issue, otherwise the cause could a worn or damaged oil pump component. In the latter case, the pump must be replaced.

So, below we explain how to clean an oil pump:

  • Keep the guide bar and chain clean: you can degrease them with diesel, petrol or a specific detergent, including concentrated degreaser supplied by Oleo-Mac.

  • Clear any sawdust, congealed lubricant and dirt out of the oil outlet hole on the guide bar.

  • Keep the oil pump tank clean: even if it is equipped with a filter, wipe away all dirt around the cap before refuelling.

  • Regularly check and clean the tank vent and the filter itself.

  • If the chainsaw has been out of action for a long time and the chain oil has solidified in the tank, rinse it out with diesel or petrol.

  • Pour some petrol (or diesel) in the oil tank and run the chainsaw for a while to flush the pump and its circuit.

  • Empty the tank and fill it with chain oil: but if you plan not to use the chainsaw for a long time, leave the tank empty.

If all of the above is not enough, you may need to remove the oil pump from the chainsaw and clean it by hand, for example by letting it soak in diesel before drying and reassembling it.

Do you want to replace your chainsaw with a new model? You can find some useful suggestions in our article on how to choose a chainsaw to match your needs.

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