Liquid fuel MSR stoves have been a staple of expeditions and remote travel since the 80s. And for good reasons. Reliable and field maintainable, capable of operating in low temperature and with the ability to run on fuels available almost anywhere. Petrols (gasoline), paraffin, kerosene etc.
For safe and effective function the critical failure point is the o-rings. Failure of any of these will cause fuel leaks and pressure loss. Replacement o-rings are typically sourced though purchase of the MSR services kits. However this is an expensive way to source a few o-rings if you already have the tool and other bits. https://amzn.to/4jcHqBy .
If you want to replace the o-rings for the standard pump I have created the following video which shows the location of the two rings in the pump and how to replace them. The large o-ring for MSR fuel bottles, and older style pumps is not included in the video. Replacing this is hopefully fairly obvious!
Note: This is my best estimtion of O-ring sizes and they have worked for me with no leaks. However if you choose to use these rather than the official o-rings this is at your own risk. Do check carefully for leaks before relying on the stove in the field.
This video covers the standard MSR pump. There are alternative versions available specific to the dragonfly and an arctic pump with upgraded seaks, although the standard pump is by far the most popular.
O-ring Sizes
MSR do not publish the I have tested the following o-ring sizes myself and work ok.
- Control valve O-ring.
- Fuel pipe O-ring
- Fuel bottle O-ring (Older style pumps)
| Description | Size (American Standard 568) | Dimensions (Metric) | Dimensions (Imperial) |
| Control Valve O-ring | -007 | 3.68 x 1.78mm | 0.145 x 0.070 inches |
| Fuel pipe O-ring | -010 | 6.07 x 1.78mm | 0.239 x 0.070 inches |
| Bottle seal (old style pumps and fuel bottles)* | -213 | 25.07mm x 3.2mm | 0.987 x 0.126 inches |
Note: * this one is best estimate. Please double check.
O-ring material
Standard o-rings are Nitrile, Buna N is a common brand. Slightly more expensive Viton O-rings are also suitable with wider operating temperature window and chemical resistance, but slightly lower low temperature flexbility. Either will work fine.