Dorman

Dorman 555-009 Engine Expansion Plug

Brand Dorman 555-009
Describe Type Cup Type
Material Steel
Maximum Diameter 0.593
Minimum Diameter 0.575
Package Contents Expansion Plug
Fits Chevrolet, Oldsmobile, and Pontiac · 5 vehicles

OE-style fit. Matches the original part's fit and function on specified vehicles.

Steel construction. Built from quality material for reliable performance.

Cup type design. A practical engine expansion plug for sealing core openings.

Cross-references Gates 31552, 260-120 and 2070787 for the same application. See all 5.

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Dorman 555-009 Engine Expansion Plug

Dorman 555-009 is a steel cup-type engine expansion plug built to match the fit and function of the original core plug on specified vehicles. It is engineered for reliable sealing in the engine block and is a direct replacement choice for select Chevrolet, Pontiac, and Oldsmobile applications.

Compatible With 1975 Chevrolet Monza, 1976-1977 Pontiac Sunbird, and 1976-1977 Oldsmobile Starfire engine applications, this engine core plug supports accurate fitment where the original plug has corroded, leaked, or deteriorated. The Dorman 555-009 is sized for a minimum diameter of 0.575 and a maximum diameter of 0.593, with a steel construction for dependable service.

Key Features

  • Steel construction for engine block sealing applications
  • Cup-type expansion plug design
  • Matches original part fit and function on listed vehicles
  • Engine core plug for select Chevrolet, Pontiac, and Oldsmobile models
  • Part number 555-009 for easy identification

Detailed Description

This Dorman engine expansion plug is made for engine hardware service where a worn or leaking core plug needs replacement. The steel cup-type design helps restore the sealing surface in the engine block, and the dimensional range of 0.575 to 0.593 supports the specified application fit. Part number 555-009 is listed for 1975 Chevrolet Monza, 1976-1977 Pontiac Sunbird, and 1976-1977 Oldsmobile Starfire engine applications. This part cross-references Gates 31552 for the same application.

What It Helps Address

  • Coolant seepage from a deteriorated engine core plug
  • Corrosion-related failure of the original expansion plug
  • Loss of sealing at the engine block opening
  • Replacement needs during engine service or rebuild work
  • Fitment issues caused by using the wrong plug diameter

Installation Notes and Tips

Verify the engine block opening size before installation and confirm the plug dimensions match the application. Clean the bore thoroughly so the steel cup-type plug seats evenly and seals properly. Use the vehicle fitment details for 1975 Chevrolet Monza, 1976-1977 Pontiac Sunbird, and 1976-1977 Oldsmobile Starfire to confirm the correct engine application before service.

Quality Assurance

Dorman designs this engine expansion plug to match the original part’s fit and function on the listed vehicles. The steel construction and application-specific sizing support consistent replacement performance for engine hardware service.

This part fits 5 vehicles
Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
YearMakeModelLitersCylindersPositionNotes
1977OldsmobileStarfire2.3LL4N/AAs Req; .010 In. Oversized; .594 In.; Package Quantity: 10; Dorman - AutoGrade - Boxed; Packaging Type: Box
1977PontiacSunbird2.3LL4N/AAs Req; .010 In. Oversized; .594 In.; Package Quantity: 10; Dorman - AutoGrade - Boxed; Packaging Type: Box
1976OldsmobileStarfire2.3LL4N/AAs Req; .010 In. Oversized; .594 In.; Package Quantity: 10; Dorman - AutoGrade - Boxed; Packaging Type: Box
1976PontiacSunbird2.3LL4N/AAs Req; .010 In. Oversized; .594 In.; Package Quantity: 10; Dorman - AutoGrade - Boxed; Packaging Type: Box
1975ChevroletMonza2.3LL4N/AAs Req; .010 In. Oversized; .594 In.; Package Quantity: 10; Dorman - AutoGrade - Boxed; Packaging Type: Box
Directly replaces or cross-references 5 part numbers
Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.
Gates — 31552260-12020707873451818EPC-54