Dorman 785-422D Pipe Plug

Dorman 785-422D Brass Pipe Plug

Dorman 785-422D is a brass pipe plug built to match the original equipment plug for diameter, thread pitch, and head type. It is engineered for a reliable seal and long service life in service and repair applications across a wide range of GM vehicles.

• Brass construction for corrosion resistance
• 1/4 in. MNPT thread size with coarse thread type
• Hex head drive for straightforward service access
• Matches OE diameter, thread pitch, and head type
• Standard-grade threaded pipe plug for leak-free performance

OE-Style Replacement Details

This pipe plug uses brass material, a 0.53 in. thread diameter, 16 threads per inch, and a 0.64 in. overall length to support a secure fit in threaded openings. The hex head and outside-thread design make it a practical replacement when servicing systems that require a 1/4 in. MNPT brass plug. This part cross-references Dayco 71870 for the same application.

Vehicle Fitment

• Fits 1989-1993 Buick Century, N/A
• Fits 1984-1985 Buick Century, N/A
• Fits 1975-1981 Buick Century, N/A
• Fits 1989-1993 Buick Skylark, N/A
• Fits 1975-1979 Buick Skylark, N/A
• Fits 1992-1993 Oldsmobile Achieva, N/A
• Fits 1984-1993 Oldsmobile Cutlass Ciera, N/A
• Fits 1987-1993 Oldsmobile Cutlass Cruiser, N/A
• Fits 1980-1983 Oldsmobile Cutlass Cruiser, N/A
• Fits 1992-1993 Pontiac Grand Am, N/A
• Fits 1979 Pontiac Grand Am, N/A
• Fits 1990-1992 Chevrolet Camaro, N/A
• Fits 1980-1981 Chevrolet Camaro, N/A
• Fits 1990-1992 Chevrolet Cavalier, N/A
• Fits 1990-1992 Chevrolet Corsica, N/A
• Fits 1990-1992 Chevrolet Lumina, N/A
• Fits 1990-1992 Pontiac Firebird, N/A
• Fits 1977-1981 Pontiac Firebird, N/A
• Fits 1989-1992 Pontiac Grand Prix, N/A
• Fits 1978-1987 Pontiac Grand Prix, N/A
• Fits 1991-1992 Pontiac Sunbird, N/A
• Fits 1976-1980 Pontiac Sunbird, N/A
• Fits 1989-1991 Oldsmobile Cutlass Calais, N/A
• Fits 1978-1984 Oldsmobile Cutlass Calais, N/A
• Fits 1988-1991 Pontiac 6000, N/A
• Fits 1990 Chevrolet Celebrity, N/A
• Fits 1985-1988 Oldsmobile 98, N/A
• Fits 1981-1983 Oldsmobile 98, N/A
• Fits 1977-1988 Oldsmobile Delta 88, N/A
• Fits 1986-1988 Oldsmobile Toronado, N/A
• Fits 1981-1984 Oldsmobile Toronado, N/A
• Fits 1980-1988 Pontiac Bonneville, N/A
• Fits 1985-1987 Oldsmobile Cutlass Salon, N/A
• Fits 1978-1980 Oldsmobile Cutlass Salon, N/A
• Fits 1977-1987 Oldsmobile Cutlass Supreme, N/A
• Fits 1976-1985 Buick LeSabre, N/A
• Fits 1975-1985 Buick Regal, N/A
• Fits 1979-1985 Buick Riviera, N/A
• Fits 1980-1984 Chevrolet Caprice, N/A
• Fits 1978-1984 Chevrolet El Camino, N/A
• Fits 1980-1984 Chevrolet Impala, N/A
• Fits 1978-1984 Chevrolet Monte Carlo, N/A
• Fits 1984 Pontiac Parisienne, N/A
• Fits 1978-1983 Chevrolet Malibu, N/A
• Fits 1977-1981 Oldsmobile Cutlass, N/A
• Fits 1977-1981 Pontiac Catalina, N/A
• Fits 1977-1981 Pontiac Grand LeMans, N/A
• Fits 1977-1981 Pontiac LeMans, N/A
• Fits 1975-1980 Buick Skyhawk, N/A
• Fits 1980 Chevrolet Monza, N/A
• Fits 1975-1980 Oldsmobile Starfire, N/A
• Fits 1977-1979 Oldsmobile Omega, N/A
• Fits 1977-1979 Pontiac Phoenix, N/A

Common Repair Uses

• Sealing a threaded port during engine or system service
• Replacing a worn, damaged, or missing brass pipe plug
• Stopping seepage from a threaded opening with the correct thread pitch
• Restoring a secure closure on a service-access port
• Matching OE-style hardware on Buick, Chevrolet, Oldsmobile, and Pontiac applications

Installation Notes

Verify the thread size, thread pitch, and head type before installation. Clean the threaded bore thoroughly, start the plug by hand to avoid cross-threading, and tighten with the correct hex tool size. Confirm the sealing surface is clean and undamaged before returning the vehicle to service. For fitment searches, this Dorman 785-422D pipe plug is commonly referenced for Buick Century, Chevrolet Camaro, and Pontiac Grand Prix applications.

Quality Assurance

Dorman manufactures replacement hardware to match original equipment dimensions and service requirements. This brass pipe plug is engineered for corrosion resistance and leak-free performance in standard repair use.