Graco 166058 Piston Seal

Restore pressure and stop bypass on select Bulldog 5:1 rubber-packed pumps with this piston packing.

Part No.: 166058 (Hycar piston seal)
Fits: Bulldog 5:1 models 206418, 207321
Role: Seals the piston for consistent output
Tip: Verify against your pump’s parts list before ordering

$118.5

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Description

Seal Function & Fitment Overview

Confirmed models that specify this piston seal in their parts list:

Graco Bulldog 5:1 Pump – Model 206418 (Rubber-Packed)
Graco Bulldog 5:1 Pump – Model 207321 (Rubber-Packed)

Key Details

Part Number	166058
Item Name (Graco)	Seal, Piston (PACKING, Hycar)
Material Family	Hycar® (nitrile rubber)
Pump Family / Type	Bulldog 5:1 Ratio – Rubber-Packed pumps
Also Supplied In	Repair Kit 206931 (per Graco parts list)

When to Replace

Loss of pressure or pulsation despite normal settings
Visible wear/flattening on old packing during service
Frequent leakage past the piston after rebuilds

Frequently Asked Questions

Open your pump’s Graco parts manual and look for the piston/packing section. If the list shows part 166058, you’re good. If it shows a different packing (e.g., 166057 for PTFE-packed variants), order that number instead.

This listing is for the piston seal itself. Related wear parts (glands, seats, V-packings) are separate unless you purchase the full repair kit referenced in the parts list.

Clean all mating surfaces, lubricate as specified by Graco, and orient the packing correctly. After reassembly, cycle at low pressure to seat the seal and check for leaks.