The Comet P40 Repair Kit is the OEM rebuild kit for the P40 diaphragm pump. It packs 3 diaphragms, 6 check valves, and 12 O-rings in one box, so you replace every wear part at once and fix low pressure and pressure fluctuation in one job.
Key Features
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Genuine Comet OEM parts: Exact fit and correct dimensions, so you're not fighting a generic aftermarket seal kit that almost works.
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Full rebuild in one box: 3 diaphragms, 6 check valves, and 12 O-rings, so every wear part gets swapped together and the pump wears evenly after.
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Desmopan diaphragms: The TPU diaphragm material Comet offers for better chemical resistance than standard Buna.
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Targets the two common P40 failures: Low pressure and pressure fluctuation both trace back to worn diaphragms, valves, and O-rings. This kit covers all three.
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Stops small problems turning into dead pumps: Replacing a worn or ruptured diaphragm before it pushes water into the crankcase keeps the pump alive.
Specifications
| Kit type |
Diaphragm and valve rebuild kit (Comet "Ordinary Maintenance Kit") |
| OEM part number |
5026.0419.00 (Comet item #105) |
| Diaphragms |
3 × Desmopan (TPU), part 1800.0088 |
| Check valves |
6 × check valve assembly, part 1220.0105 (each carries its own O-ring) |
| O-rings |
12 total, part 1210.0506, 3.53 × 34.52 mm |
| Fits |
Comet P40 and P40/20 Series, old style and new style |
| Does not fit |
Comet MC25 (uses a separate kit) |
What's Included
- 3 Desmopan diaphragms (1800.0088)
- 6 check valve assemblies (1220.0105)
- 12 O-rings (1210.0506)
Fits the Comet P40 and P40/20 Series, both old and new style. It doesn't fit the Comet MC25, which takes a different kit. This kit rebuilds the pump wear parts only. It doesn't service the pressure regulator, which has its own separate kit.
How It Works
The P40 is a 3-diaphragm semi-hydraulic pump. The diaphragms flex to pull chemical and water in and push it back out. The six check valves keep flow moving one way, and the O-rings seal the manifold and valve seats. As these parts wear, the pump loses pressure and the output starts to surge. This kit replaces all of them at once so the pump wears evenly instead of dying one part at a time.
One step you can't skip: after you fit the new diaphragms, purge all the air from the crankcase oil before you start the pump. Turn the crankshaft by hand while rocking the pump. Skip it and you can blow a fresh diaphragm or turn the oil milky on the first run.
Pairs Well With
Frequently Asked Questions
Does the Comet P40 Repair Kit fit both the old and new style P40?
Yes. It fits the P40 and P40/20 Series in both old and new style. It doesn't fit the Comet MC25, which uses a different rebuild kit.
How do I know my P40 diaphragms need replacing?
Milky or whitish-gray oil in the sight glass means a diaphragm may have ruptured. Stop the pump and rebuild before water wrecks the crankcase. Low pressure and surging output are the earlier warning signs.
Does this kit rebuild the pressure regulator too?
No. The regulator is a separate kit. This one covers the diaphragms, check valves, and O-rings that wear out inside the pump.
