Comet MC25 Diaphragm Pump Parts & Repair Guide

The Comet MC25 is one of the most popular diaphragm pumps on pest control and landscape spray rigs, and we see a lot of them in our Phoenix shop. QSpray stocks the Comet MC25 pump and its key repair parts, all on one easy-to-find page, along with the parts breakdown and instruction manual to help you fix it.

Comet MC25 Parts Breakdown and Manual

Before ordering parts, download the parts breakdown to find the exact part numbers for your pump:

• Download the Comet MC25 Diaphragm Pump Parts Breakdown (PDF)
• Download the Comet Diaphragm Pump Instruction Manual (PDF)

Signs Your MC25 Needs Service

Milky or discolored pump oil. If the oil in the crankcase turns milky or takes on the color of your spray mix, a diaphragm has likely ruptured and liquid is getting into the oil. Stop running the pump right away. Continuing can destroy the internal parts. Replace the diaphragms and change the oil.

Loss of pressure or uneven output. Worn or debris-clogged valves are a common cause. Check and clean the valves, and replace them if they're worn.

Leaks. Leaking around the pump body usually points to worn O-rings or seals.

With heavy use, we recommend planning on new diaphragms and valves about once a year, before they fail on the job. Always follow Comet's instruction manual for service intervals and procedures.

Popular MC25 Parts

The Comet 0418.0018 Clip is one of the most commonly replaced MC25 parts. See the full selection on our Comet MC25 pump and parts page.

Engine Pairing

The MC25 is commonly paired with a Honda GX160 gear-reduction engine, which drives the pump at the lower speed diaphragm pumps are designed for. If you're replacing the engine too, see our Honda GX160 6:1 gear reduction engine.

Need Help?

Not sure which part you need, or want us to rebuild your pump? Our shop services Comet pumps and the rigs they run on. Contact us or call 602-371-1993. You can also browse all Comet diaphragm pumps and our full line of sprayer pumps.