Monarch Jet Pumps – Shallow Well – MJS & Deep Well – MJC
- MJC-50, MJC-75, and MJC-100 convertible jet pumps and parts
- MJSE-50 jet utility pump with hose adapter and 115V cord
- MJC reaches wells up to 80 or 90 feet by model
- Minor and major overhaul kits listed by horsepower
- Shared seal, gasket, and diffuser codes across both series
- Send us your MJC or MJSE nameplate and we will confirm parts
The kitchen tap runs weak every time the well pump kicks on, and the pump in the basement is an old MJC. A Monarch jet pump like this can be rebuilt with an overhaul kit, and its part codes are still listed. This page covers the MJC convertible pumps and the MJSE-50, their kits and codes, and what to do when a rebuild no longer makes sense.
Rebuilding an MJC or MJSE-50: Kits and Codes
Both the MJC and the MJSE-50 can still be repaired from their Monarch parts lists. Minor overhaul kits replace the impeller, seal, and pump gasket, and major kits add the diffuser. For a new pump, send us the model number and we will confirm the current equivalent.
MJC and MJSE-50 at a Glance
| Model | Order No. | HP | Service factor | Voltage | Built for |
|---|---|---|---|---|---|
| MJSE-50 | 614431 | 1/2 | 1.90 | 115V, 8 ft cord | Sprinklers, pressure boosting, hose transfer |
| MJC-50 | 602032 | 1/2 | 1.90 | 115/230V | Shallow wells, or deep wells to 80 feet |
| MJC-75 | 602033 | 3/4 | 1.65 | 115/230V | Shallow wells, or deep wells to 90 feet |
| MJC-100 | 602034 | 1 | 1.65 | 115/230V | Shallow wells, or deep wells to 90 feet |
Every MJC has a 1-1/4 inch NPT suction and a 1 inch NPT discharge. The MJC-50 also came as the MJC-50/PC25S package, with an 8.5 gallon tank.
Monarch Jet Pump Parts by Code Number
| Part | MJSE-50 | MJC-50 | MJC-75 and MJC-100 |
|---|---|---|---|
| Mechanical seal, 5/8 inch | 240104 | 240104 | 240104 |
| Pump gasket | 192785 | 192785 | 192785 |
| Diffuser | 246233 | 246233 | 246233 |
| Impeller | 468096 | 246251 | 246236 |
| Minor overhaul kit | 497151 | 697151 | 697152 |
| Major overhaul kit | 497155 | 697155 | 697156 |
The MJC parts list also carries the pressure switch (224228), pressure gauge (633652), injector body (424705), and valve assembly (201415). Nozzles and venturis differ by horsepower and by shallow or deep setup, so give us both when you order.
Shallow or Deep: How the MJC Converts
For a shallow well, the injector bolts straight to the pump casing. For a deep well, the injector assembly goes down inside the well, which lets the MJC reach water up to 80 or 90 feet down, depending on the model.
Each MJC shipped with the deep well venturi loose in the carton, a pressure gauge, and a Square D pressure switch set at 30-50 PSI. The motor is a dual voltage A.O. Smith with a stainless steel shaft and a John Crane Type 6 seal.
MJSE-50: A Jet Pump for Sprinklers and Hose Work
The MJSE-50 plugs into a standard 115 volt outlet and takes a garden hose through its adapter. With 5 feet of suction lift, it moves 12.8 GPM at 20 PSI and 6.9 GPM at 50 PSI.
For larger lawn systems with several zones, compare the self-priming models on the Monarch sprinkler pump page.
When a Rebuild Is Not Worth It
A cracked casing or a failed motor can make a new pump the better buy. For an MJS shallow well pump, a reseller lists the Little Giant JP-075-C as the replacement for the MJS-75, so send us your model number and we will confirm the match. Browse current models among the Little Giant shallow well jet pumps.
For an MJC, send us the model number and we will confirm the current equivalent. The MJC charts stop at 90 feet of lift, so a deeper well needs a different kind of pump.
To compare other motor driven series, see the Monarch electric motor pump section. If you are matching an unmarked part, our guide to finding the right Monarch parts can help.
Frequently Asked Questions
My jet pump won't shut off. What could be the problem?
A jet pump that won't shut off has not reached the cut-out pressure on its switch. On a Monarch MJC, the Square D switch is set at 30-50 PSI, so watch the gauge. If it stalls below 50 PSI, check for air leaks on the suction line, a lost prime, or the wrong nozzle and venturi for your well depth. A worn impeller or diffuser also lowers pressure, and the major overhaul kit replaces both.
How to rebuild a jet pump?
To rebuild a jet pump, shut off the power, drain the casing, and unbolt the motor and seal plate from the casing. Remove the impeller, replace the seal halves, and fit the new impeller, diffuser, and gasket from the overhaul kit. Bolt it back together, fill the casing with water, and restart. On a Monarch MJC, the minor kit covers the impeller, seal, and gasket, and the major kit adds the diffuser.
Is the pressure switch included with the MJC?
Yes, the pressure switch is included with every MJC. Each pump shipped with a Square D switch set at 30-50 PSI, a pressure gauge, and the deep well venturi loose in the carton. If the switch fails, the replacement is code 224228 and the gauge is code 633652. The MJSE-50 parts list has no pressure switch, since that pump runs from its cord and a garden hose adapter.
Ready to order? Send us the model and order number from your Monarch jet pump and we will quote the kit, part, or replacement.