Home› Brake > Gaskets and Sealing Systems› Dorman 42070 Brake Master Cylinder Reservoir Cap Gasket
Dorman 42070 Brake Master Cylinder Reservoir Cap GasketOE Quality 60-Day Returns
Part #: 42070

Dorman 42070 Brake Master Cylinder Reservoir Cap Gasket

N/A
105 vehicles fit this part
Select your vehicle to confirm fitment
Verify this part fits before purchasing — free returns if it doesn't
$28.18Free Shipping
Free ShippingNo Cost to Continental U.S.
Free Returns*Wrong fit? No cost
60-Day ReturnsMoney back guarantee
*Free return shipping only qualifies if our fitment verification tool is used.
In Stock · Ready To Ship Most orders ship same-day if ordered before 1pm CST.
OE Direct Replacement — Bolt-on fit, no modifications needed
Fitment: Chevrolet, Pontiac, Buick, Oldsmobile, GMC, and Cadillac, Chevette, T1000, Skyhawk, Monza, Starfire, Sunbird, Vega, Astre, Apollo, Nova, Omega, Ventura, Electra, GS, GS 455, Riviera, Skylark, Sportwagon, Chevelle, El Camino, Monte Carlo, Sprint, Cutlass, Cutlass Supreme, F85, Vista Cruiser, Grand Prix, GTO, LeMans, 442, LeSabre, Wildcat, 98, Delta 88, Bonneville, Catalina, Executive, Tempest, GS 350, GS 400, Special, Firebird, Calais, DeVille, Eldorado, Fleetwood, and Delmont 88
Easy Returns — Return within 60 days for a full refund
Fast Shipping — Most orders ship same business day before 1pm CST
Not what you need? See all Brake Master Cylinder Reservoir Cap Gasket options

Brake Master Cylinder Reservoir Cap Gasket for OE Fit

This Dorman brake master cylinder reservoir cap gasket is built to match the original gasket’s fit and function on specified vehicles. Made from rubber, it helps maintain a proper seal at the reservoir cap for dependable brake system performance.

  • Rubber construction for sealing performance and durability
  • Direct-fit replacement for the original brake master cylinder reservoir cap gasket
  • Designed for specified Buick, Chevrolet, Oldsmobile, Pontiac, and Cadillac applications
  • Cross-references Dorman 420704 and 5470861 for the same application
  • Part number 42070 for brake master cylinder reservoir service

Detailed Product Overview

Dorman 42070 is a brake master cylinder reservoir cap gasket engineered to match the fit and function of the factory gasket on listed vehicles. It is used in brake master cylinder reservoir sealing applications where a stable rubber gasket is needed to help maintain the cap-to-reservoir seal. This part number 42070 is a practical OE-style replacement for service work on classic GM platforms, including Chevrolet Chevette, Pontiac Sunbird, Buick Skylark, and related models.

Compatible With 1968-1987 Buick, Chevrolet, Cadillac, Oldsmobile, and Pontiac vehicles listed in the fitment data, including applications such as 1978-1987 Chevrolet Chevette, 1971-1974 Chevrolet Nova, 1968-1972 Pontiac GTO, and 1968 Cadillac DeVille. The fitment also includes specific configurations such as Moraine brakes, front drum brakes, and cast iron original cylinder applications where noted.

What This Part Helps Address

  • Brake fluid seepage at the master cylinder reservoir cap
  • Loss of sealing at the reservoir opening
  • Degraded or hardened original rubber gasket material
  • Service needs on aging brake master cylinder reservoirs
  • Replacement during brake system maintenance on classic GM vehicles

Installation Notes and Tips

Inspect the reservoir cap and sealing surface before installation. Clean the mating surfaces thoroughly and confirm the gasket seats evenly in the cap groove or reservoir interface. Verify the vehicle’s brake system configuration against the listed fitment notes, especially where Moraine brakes, front drum brakes, or cast iron original cylinder references are specified.

Quality Assurance

Dorman designs this gasket to match original fit and function on specified vehicles and to provide durable, reliable service in brake system applications. Part number 42070 is supported by listed interchange references for the same application.

BrandDorman
Part Number42070
MaterialRubber
Package Contents1 Brake Master Cylinder Gasket

This part fits 105 vehicles. Search below:

YearMakeModelPositionNotes
1987ChevroletChevetteN/A
1987PontiacT1000N/A
1986ChevroletChevetteN/A
1986PontiacT1000N/A
1985ChevroletChevetteN/A
1985PontiacT1000N/A
1984ChevroletChevetteN/A
1984PontiacT1000N/A
1983ChevroletChevetteN/A
1983PontiacT1000N/A
1982ChevroletChevetteN/A
1982PontiacT1000N/A
1981ChevroletChevetteN/A
1981PontiacT1000N/A
1980BuickSkyhawkN/A
1980ChevroletChevetteN/A
1980ChevroletMonzaN/A
1980OldsmobileStarfireN/A
1980PontiacSunbirdN/A
1979BuickSkyhawkN/A
1979ChevroletChevetteN/A
1979OldsmobileStarfireN/A
1979PontiacSunbirdN/A
1978BuickSkyhawkN/A
1978ChevroletChevetteN/A
1978OldsmobileStarfireN/A
1978PontiacSunbirdN/A
1977BuickSkyhawkN/ACast Iron Original Cylinder
1977ChevroletChevetteN/ACast Iron Original Cylinder
1977ChevroletMonzaN/ACast Iron Original Cylinder
1977OldsmobileStarfireN/ACast Iron Original Cylinder
1977PontiacSunbirdN/ACast Iron Original Cylinder
1976BuickSkyhawkN/ACast Iron Original Cylinder
1976ChevroletMonzaN/ACast Iron Original Cylinder
1976OldsmobileStarfireN/ACast Iron Original Cylinder
1976PontiacSunbirdN/ACast Iron Original Cylinder
1975BuickSkyhawkN/Aw/Moraine Brakes
1975OldsmobileStarfireN/A
1974ChevroletNovaN/A
1974OldsmobileOmegaN/A
1973ChevroletNovaN/A
1973OldsmobileOmegaN/A
1972BuickRivieraN/AFront Drum Brakes
1972BuickSkylarkN/A
1972ChevroletEl CaminoN/A
1972ChevroletMonte CarloN/A
1972ChevroletNovaN/A
1972OldsmobileCutlassN/A
1972OldsmobileCutlass SupremeN/A
1972PontiacGrand PrixN/AFront Drum Brakes
1972PontiacGTON/A
1972PontiacLeMansN/A
1971BuickRivieraN/AFront Drum Brakes
1971BuickSkylarkN/A
1971ChevroletEl CaminoN/A
1971ChevroletMonte CarloN/A
1971ChevroletNovaN/A
1971OldsmobileCutlassN/A
1971OldsmobileCutlass SupremeN/A
1971PontiacGrand PrixN/AFront Drum Brakes
1971PontiacGTON/A
1971PontiacLeMansN/A
1970BuickLeSabreN/Aw/Moraine Brakes
1970BuickRivieraN/Aw/Moraine Brakes
1970BuickSkylarkN/A
1970Oldsmobile98N/A
1970OldsmobileCutlassN/A
1970OldsmobileDelta 88N/A
1970PontiacBonnevilleN/Aw/Moraine Brakes
1970PontiacCatalinaN/Aw/Moraine Brakes
1970PontiacGrand PrixN/Aw/Moraine Brakes; Front Drum Brakes
1970PontiacGTON/A
1970PontiacLeMansN/A
1970PontiacTempestN/A
1969BuickLeSabreN/Aw/Moraine Brakes
1969BuickRivieraN/Aw/Moraine Brakes
1969BuickSkylarkN/A
1969Oldsmobile98N/Aw/Moraine Brakes
1969OldsmobileCutlassN/Aw/Moraine Brakes
1969OldsmobileCutlass SupremeN/Aw/Moraine Brakes; Front Drum Brakes
1969OldsmobileDelta 88N/Aw/Moraine Brakes
1969PontiacBonnevilleN/Aw/Moraine Brakes
1969PontiacCatalinaN/Aw/Moraine Brakes
1969PontiacFirebirdN/A
1969PontiacGrand PrixN/A
1969PontiacGTON/A
1969PontiacLeMansN/A
1969PontiacTempestN/AFront Drum Brakes
1968BuickLeSabreN/Aw/Moraine Brakes
1968BuickRivieraN/Aw/Moraine Brakes
1968BuickSkylarkN/A
1968CadillacDeVilleN/A
1968CadillacEldoradoN/AFront Drum Brakes
1968CadillacFleetwoodN/A
1968Oldsmobile98N/Aw/Moraine Brakes
1968OldsmobileCutlassN/Aw/Moraine Brakes
1968OldsmobileCutlass SupremeN/Aw/Moraine Brakes; Front Drum Brakes
1968OldsmobileDelta 88N/Aw/Moraine Brakes
1968PontiacBonnevilleN/Aw/Moraine Brakes
1968PontiacCatalinaN/Aw/Moraine Brakes
1968PontiacFirebirdN/A
1968PontiacGrand PrixN/A
1968PontiacGTON/A
1968PontiacLeMansN/A
1968PontiacTempestN/AFront Drum Brakes

* Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.

This part directly replaces or is cross-referenced with the following part numbers:

4207045470861

Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.