Husqvarna Worm Wheel for 550XP Mark II

The Husqvarna 550XP Mark II oil pump worm gear, called the worm wheel in Husqvarna parts lists, drives the bar oil pump from the crankshaft. When its teeth wear or strip, the pump stops turning and the bar and chain run dry, which ruins both fast.

Diagnosing an oiling problem

If the bar is dry, the chain smokes or turns blue, or there is no oil flick when you run the saw at a stump, the oil system needs a look. Start simple: check the oil tank, filter, bar oil hole and the oil port in the bar. If those are clear, the worm gear may be worn or stripped.

Worn worm gears are common on saws that see lots of hours, especially if the chain has been run dry.

Many oiling problems are caused by a clogged oil port in the bar or a blocked oil filter, so check those first. If the oil level never drops, or the chain stays dry even with a clean bar and full tank, the worm gear or pump is likely at fault. The 550XP Mark II is a popular saw for limbing and bucking, so keeping its oil system working is important for bar and chain life.

Replacing the worm wheel

Remove the bar, chain, clutch and possibly the oil pump to access the gear. Check the pump drive while you are there. Install the new gear, reassemble and check for oil flow.

Running a saw without bar oil wears the bar and chain quickly. See more 550XP Mark II parts in our chainsaw parts section.