Overview
Seal set for the HydraMaster high-pressure by-pass valve, listed in the parts list as Seal Set for By-pass Valve.
The by-pass valve regulates solution pressure and dumps the excess back to the water box. When its seals wear, pressure becomes unstable or will not hold at the set point — the machine reads fine at rest and drops away under trigger.
What it fits
- By-pass valve 169-101 (Valve, By-Pass Truckmount)
- Item 3 in the by-pass valve assembly, fitted with seat and o-ring 148-004, fitting o-ring 097-005 and high-PSI spring 155-019
Repairing the whole valve
HydraMaster also list two kits that contain this seal set:
- 078-101 — seal and spring kit for the high-PSI by-pass (includes this seal set and the spring)
- 078-102 — complete by-pass repair kit (includes 078-101)
Neither kit is currently held by CCW. If the valve is worn enough to need the spring as well, contact us before ordering the seal set on its own.
Identifying the right part
CCW part codes are the HydraMaster part number with the 000- prefix removed — this item is HydraMaster P/N 000-097-028.
HydraMaster truckmounts share components across models and production years. If you are ordering for an existing machine, send us the model and serial number from the data plate and we will check it against the parts list for your machine.
Confirmed against the HydraMaster CDS 4.2 / 4.7 machine assemblies and parts lists. Fitment to other HydraMaster models has not been verified from a parts list — ask us if you are ordering for a different machine.
O-Ring Kit for HydraMaster 169-101 bypass valve
Important — two o-ring kits, two different valves
CCW lists an o-ring kit for the solution valve and a seal set for the by-pass valve. They service different valves and do not interchange.
| This seal set (097-028) | 078-019 | |
|---|---|---|
| Valve | By-pass valve 169-101 | Solution valve 169-058 |
| What it does | Regulates solution pressure, dumps excess to the water box | The trigger valve in the wand or tool |
| Symptom | Pressure unstable, or will not hold at the set point — reads fine at rest and drops away under trigger | Trigger valve weeps, or will not shut cleanly |
Related parts
- Repair O-Ring Kit, Solution Valve (078-019) — the other valve; see the table above
- CAT Thermo Valve 180° (169-011) — high temperature control in the same circuit
Frequently asked questions
My pressure drops away under trigger. Is this the fix?
It is the first thing to check. Worn by-pass seals let pressure bleed off under load while the gauge still reads correctly at rest.
Is this the same as the solution valve kit?
No. See the table above — different valve, different symptom.
Do you stock the complete by-pass valve?
Not as a listed line. Send us your machine model and serial number and we will work out what you need.
