Keep your cooling system topped off and manage coolant expansion with the Dorman - OE Solutions Engine Coolant Reservoir 603-111. This non-pressurized reservoir holds excess coolant and lets it return to the system as temperatures change. It drops in as a direct-fit replacement for the 1994-2003 Chevrolet S10 (L4-2.2L), 1994-2004 Chevrolet S10 (V6-4.3L), 1994-2003 GMC Sonoma (L4-2.2L), 1994-2004 GMC Sonoma (V6-4.3L), 1995-2005 Chevrolet Blazer (V6-4.3L), 1995-2005 GMC Jimmy (V6-4.3L), and 1996-2001 Oldsmobile Bravada (V6-4.3L).
- Direct replacement: engineered to match the original part's fit and function on the listed applications.
- Durable construction: molded from plastic to withstand underhood heat and engine vibration.
- Seamless installation: designed for a straightforward install.
- Trustworthy design: backed by Dorman's 100 years of automotive aftermarket experience.
The white plastic tank is non-pressurized and includes a cap; package contents are one cap and one coolant reservoir. It has two mounting holes, but mounting hardware and mounting brackets are not included — consult the vehicle service information for the correct fasteners and whether they may be reused. Signs the original reservoir may need replacing include cracks, coolant seepage or staining, and a dropping coolant level; if the reservoir is the cause, this unit replaces it. Country of origin: Taiwan.
Interchange: Manufacturer part number 603-111.
This part cross-references / interchanges with the following part numbers:
Frequently Asked Questions
Is this coolant reservoir pressurized?
No. Per the manufacturer specs, 603-111 is a non-pressurized coolant reservoir.
Does it come with a cap?
Yes. The catalog lists a cap as included, and package contents are one cap and one coolant reservoir.
Are mounting hardware and brackets included?
No — neither mounting hardware nor mounting brackets are included. Consult the vehicle service information for the correct fasteners and whether they may be reused.
Which vehicles does this fit?
It fits the listed Chevrolet S10 and Blazer, GMC Sonoma and Jimmy, and Oldsmobile Bravada applications with the L4-2.2L or V6-4.3L engine. See the description or Buyer's Guide tab for the exact years.
What are signs my coolant reservoir needs replacing?
Cracks, coolant seepage or staining around the tank, and a dropping coolant level. If a failed reservoir is the cause, this unit replaces it.
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