Home SIMPSON Pressure Washer Parts & Compatibility
Brand parts & accessory matching
SIMPSON Pressure Washer Parts & Compatibility
SIMPSON publishes unusually useful pump and accessory specifications, but the correct part still depends on the exact pressure-washer and installed component. Use model and part numbers first, then match shaft, connection, PSI, GPM and temperature.
SIMPSON part selection is unusually sourceable
SIMPSON publishes current replacement pump kits, accessory model numbers, machine manuals and many replacement-parts lists. Use those exact identifiers before shopping.
If you only know the pressure-washer model, start at the SIMPSON brand hub and identify the installed pump/accessory system.
Current SIMPSON replacement-pump classes
For a pump-family comparison of 90036, 90037, 90038, 90039 and 90034 independent of the complete SIMPSON machine, see the AAA Pressure Washer Pump Guide.
| Pump | Published output | Shaft / orientation | Compatibility use |
|---|---|---|---|
| OEM 90026 | 3100 PSI / 2.4 GPM | 7/8-in / vertical | Vertical-engine axial-cam replacement class. |
| OEM 90028 | 3300 PSI / 2.4 GPM | 3/4-in / horizontal | Horizontal axial-cam replacement class; engine examples are not whole-machine guarantees. |
| OEM 90029 | 3400 PSI / 2.5 GPM | 3/4-in / horizontal | Higher-output horizontal axial-cam class. |
| AAA 90036 | 3200 PSI / 2.8 GPM | 3/4-in / horizontal | Triplex replacement class for compatible horizontal engines. |
| AAA 90039 | 4000 PSI / 3.5 GPM | 1-in / horizontal | Professional triplex class; SIMPSON explicitly says to check inlet/outlet orientation. |
| AAA 90034 | 4400 PSI / 4.0 GPM | 1-in / horizontal | High-output triplex class; downstream components must support the resulting system. |
Use the Pump Finder to filter the initial documented dataset, but final machine fit remains conditional until mounting, shaft length/keying, RPM/power, ports and clearance are verified.
Hose families use different interfaces
Current SIMPSON accessories show why “SIMPSON hose” is not a single connection standard. MorFlex replacement/extension hoses include 1/4- and 5/16-inch products with M22 connections, while Monster commercial-style hoses use 3/8-inch quick connects. Armor hot/cold hoses add a higher temperature class.
Use the exact hose model and the hose compatibility guide rather than substituting by length or PSI alone.
Spray guns, wands and nozzles
| Accessory | Current published detail | Selection note |
|---|---|---|
| Spray Gun 80147 | 3400 PSI / 8.0 GPM / 140°F; M22 male hose connection and M22 female wand connection | Cold-water residential replacement class. |
| Spray Gun 80178 | 5075 PSI / 12 GPM / 212°F; professional threaded ports/adapters | Higher-output/hot-water class; identify installed fittings. |
| Nozzle Kit 80145 | #3.0 orifice; up to 3600 PSI; five 1/4-in QC tips | Match machine flow/pressure before choosing by color. |
| Nozzle Kit 80146 | #4.0 orifice; up to 4500 PSI; five 1/4-in QC tips | Higher-flow/orifice class, not a generic upgrade. |
| Surface Cleaner 80299 | 15 in; 1500–3700 PSI; 1.8 GPM minimum; 1/4-in QC; cold water | Match machine output and wand-side connection. |
| Surface Cleaner 80625 | 16.5 in; 2000–4000 PSI; 2.5–4.0 GPM; 1/4-in QC | Flow range is as important as diameter. |
AAA 90039: only after the shaft and machine checks pass
AAA 90039 is a documented 4000 PSI / 3.5 GPM, 1-inch horizontal-engine replacement class. It is not a universal “SIMPSON 4000 PSI pump.”
Manufacturer sources
- SIMPSON — current replacement pumps
- SIMPSON — AAA 90039 pump kit
- SIMPSON — current accessories / parts categories
- SIMPSON — Spray Gun 80147
- SIMPSON — Nozzle Kit 80145 (#3.0)
- SIMPSON — Nozzle Kit 80146 (#4.0)
- SIMPSON — Surface Cleaner 80299
- SIMPSON — Surface Cleaner 80625
Sources reviewed August 28, 2026. PressureWasherMatch.com is independent and is not affiliated with or endorsed by SIMPSON.
Frequently asked questions
How do I identify the correct SIMPSON replacement pump?
Use the exact washer and existing pump model first. SIMPSON replacement-pump pages publish orientation, shaft diameter, PSI/GPM and example engine classes, but final fit also requires mounting, shaft length/keying, RPM/power, port orientation, unloader and clearance checks.
What is the SIMPSON AAA 90039 pump rated for?
SIMPSON currently lists AAA 90039 at 4000 PSI and 3.5 GPM with a 1-inch shaft for gas pressure washers with horizontal engines. The manufacturer still instructs users to check inlet/outlet orientation for compatibility.
Are SIMPSON MorFlex and Monster hoses interchangeable?
Not automatically. Current MorFlex examples use smaller hose IDs and M22 connections, while Monster commercial-style hose examples use 3/8-inch quick connects. Match pressure, temperature, hose ID, length and both ends.
Are SIMPSON spray guns universal?
Some are sold as universal within explicit limits. For example, 80147 uses M22 connections and is rated up to 3400 PSI and 8.0 GPM for cold water. Higher-output or hot-water machines may require a different gun.
How do I choose SIMPSON replacement nozzles?
Use machine GPM and target pressure to determine orifice size, then match the nozzle kit rating and quick-connect interface. SIMPSON 80145 is a #3.0 orifice kit rated to 3600 PSI; 80146 is #4.0 rated to 4500 PSI.
Should I repair or replace a SIMPSON pump?
It depends on the pump model, failure and available service kits. Identify the pump first, use the exact parts list or kit, and compare repair scope with a verified replacement pump. Do not rebuild an unidentified pump from generic seal dimensions alone.