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Graco 164391 Backup Washer

Keep your sprayer leak-free with the Graco 164391 Washer, Backup—a support ring that stabilizes seals under pressure.

  • Function: Backs up O-rings to prevent extrusion and leakage.
  • Typical Location: Pump/valve sealing stack in Graco sprayers.
  • When to Use: During rebuilds or if pressure loss/fluid seep is observed.
  • Fit Check: Confirm part callout 164391 in your model’s parts manual.
  • Pro Tip: Replace with adjacent O-rings for best sealing performance.

$34.02
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Compatible Machines

At this time, a model-by-model list for Graco 164391 is not confirmed. Please verify against your unit’s parts manual (pump/valve section) before ordering.


Overview & Key Details

The Graco 164391 is a precision Washer, Backup used to support seals and help prevent leakage in Graco spray equipment assemblies.

Part Number 164391
Item Name Washer, Backup
Function Supports primary seals/O-rings to improve sealing and reduce extrusion under pressure.
Typical Location Pump, valve, or fluid section interfaces within Graco sprayer assemblies.
Use Case Maintenance or rebuilds where restoring leak-free performance is required.

Why this part matters

  • Provides backup support to sealing elements under operating pressure.
  • Helps maintain leak prevention and consistent pressure performance.
  • Designed to fit specific assemblies within Graco equipment (confirm via manual/kit).

Installation & Fit Guidance

  • Match the 164391 callout in your sprayer’s exploded view before purchase.
  • Inspect adjacent O-rings/seals; replace as a set if wear or deformation is present.
  • Lubricate per Graco guidelines during reassembly to protect sealing surfaces.

Frequently Asked Questions

Check the parts manual for your exact model and pump/fluid section. Look for the part callout 164391 in the diagram or the bill of materials. If your manual lists a kit, verify whether this Washer, Backup is included in that kit number.
Frequently Asked Questions
Where to check Pump section / valves / fluid manifold pages in the manual
What to match Exact part number 164391 or kit contents
Tip Compare dimensions/shape with the removed backup washer

Common indicators include fluid seepage at seal interfaces, inability to hold pressure, or visible deformation/extrusion of the sealing stack. During rebuilds, replace the Washer, Backup along with associated O-rings for best results.

Reuse is not recommended. Even minor wear can compromise seal support under pressure. For reliability, install a new Graco 164391 when servicing the sealing stack.

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