Ask Don · 20261005_160000_stant-27278-thermostat-seal-fitment-guide

Stant 27278 Thermostat Seal – Fitment Guide for Cadillac, Volvo (1967–1994)

Cadillac, Volvo (1967–1994)

Stant 27278 Engine Coolant Thermostat Seal – from Don's Obsolete Auto Parts

Keep your car or truck on the road with a genuine Stant 27278, the Stant thermostat seal for Cadillac 4.1L, 4.5L and 4.9L V8s (1985–1994 DeVille, Eldorado, Fleetwood, Seville, Allante, Sixty Special) and Volvo fours from the 1967 122 through the 240, 260, 740, 760, 780 and 940, plus the 1992 960. A thermostat seal is a molded rubber ring that seals the thermostat or the water outlet instead of a flat paper gasket. Stant's description of these seals: no sealer or RTV is needed, and each one is shaped for its application.

Key Features

• Part Number: Stant 27278 (single pack); same seal as Stant 25278 in the Stant catalog
• Type: Engine coolant thermostat / water outlet seal (rubber, grooved, molded style per the Gates equivalent)
• Size: about 2.004 in. inside diameter × 2.284 in. outside diameter × 0.173 in. thick (Gates 33616 data for the direct equivalent)
• Cross-references: Gates 33616; Carquest 30730; Dayco 82511; Fel-Pro 35278; General Motors 3522626, 3522676; Ideal Tridon 30985; McCord 74-0145; NAPA 1091

Stant's own 1928–1994 application catalog lists the 27278 for 2 makes from 1967 to 1994. It's a good fit for restoration projects, weekend drivers and mechanics keeping older vehicles running.

Compatible Makes & Models (from the Stant catalog)

• Cadillac (1985–1994): Allante (1987–1992), DeVille (1985–1994), Eldorado (1986–1993), Fleetwood (1985–1992), Seville (1986–1993), Sixty Special (1993)
• Volvo (1967–1994): 122 (1967), 240 (1976–1993), 260 (1980–1981), 740 (1985–1992), 760 (1984–1990), 780 (1989–1991), 940 (1991–1994), 960 (1992)

Note: Always verify fitment for your specific year, make, model and engine. Some catalog lines are limited to one engine code or housing type; the full engine-by-engine list is in the fitment appendix below. If you have your old seal, compare its size and shape, or just ask Don and Kathy.

Current retailer listings (PartsHawk) show 27278 as "replaced by 27285" for new orders. That is a later supersession, not a change to the 1928–1994 applications listed here.

Price is $9.95 plus $3.00 for shipping. Don and Kathy offer a fair deal for this. Buying for a club, a shop, or a whole fleet of project cars? Even better.

Why Buy From Don & Kathy at Don's Obsolete Auto Parts? Don Leask founded one of the earliest online obsolete auto parts businesses (carparts2 on eBay in 1997, the second auto parts store on eBay) and grew it to 11,000–17,000 unique listings. Today, with help from their digital agent Misty ([email protected]), Don and Kathy connect directly with restorers and collectors while preserving their legacy of quality parts. These seals come from Don's own shelves.

To reach them, click the "Don & Kathy Leask" button at the bottom left of any page on donsobsoleteautoparts.com, or email [email protected].

The Stant 27278 Thermostat Seal: The Right Seal for Cadillac and Volvo Owners

Thermostat seals are small, but they decide whether a cooling system stays dry. When the thermostat housing comes off, the right seal is the quiet part that keeps the job from turning into a second trip to the parts counter.

Why This Seal Matters Stant's application catalog covering 1928 through 1994 lists the 27278 across 2 makes (Cadillac, Volvo). Cross-reference tables tie it to the Stant 25278 and Gates 33616, which makes it easy to match against an old parts list or a worn-out seal.

Real-World Fitment Examples

• 1987–1988 Cadillac Allante V-8 4.1L
• 1967 Volvo 122 4-Cyl. 109 cu in

Keeping Older Cars on the Road Don and Kathy Leask have been part of the classic car world since the early days of the internet. Starting with carparts2 on eBay in 1997, they became one of the largest online sellers of obsolete parts. Now, with their Don's Obsolete Auto Parts site and digital agent Misty, they're making hard-to-find parts discoverable again, connecting owners of rare inventory with the enthusiasts who need them.

Buying Tips

• Match three things before ordering: year, model and engine. Watch for catalog notes such as engine VIN codes or housing type.
• Compare sizes: the 27278 is about 2.004 in. inside diameter × 2.284 in. outside diameter × 0.173 in. thick.
• Some engines use a gasket and a seal at the thermostat; check what came off yours.
• Restoration shops, clubs and collectors can ask about quantity pricing.

Fitment appendix — every Stant catalog line for

27278

Source: Stant Thermostats, Gaskets, Caps – 1928 through 1994 (application pages). Format: Model — years [engine: years (catalog notes)]. Catalog coverage ends with 1994 models.

Cadillac

• Allante — 1987–1992 [V-8 4.1L: 1987–1988 | V-8 4.5L: 1989–1992]
• DeVille — 1985–1994 [V-8 4.1L: 1985–1987 | V-8 4.5L: 1988–1990 | V-8 4.9L: 1991–1994]
• Eldorado — 1986–1993 [V-8 4.1L: 1986–1987 | V-8 4.5L: 1988–1990 | V-8 4.9L: 1991–1993]
• Fleetwood — 1985–1992 [V-8 4.1L: 1985–1987 | V-8 4.5L: 1988–1990 | V-8 4.9L: 1991–1992]
• Seville — 1986–1993 [V-8 4.1L: 1986–1987 | V-8 4.5L: 1988–1990 | V-8 4.9L: 1991–1993]
• Sixty Special — 1993 [V-8 4.9L: 1993]

Volvo

• 122 — 1967 [4-Cyl. 109 cu in: 1967]
• 240 — 1976–1993 [4-Cyl. 130 cu in: 1976–1979 | 4-Cyl. 2.1L: 1980–1984 | 4-Cyl. 2.3L: 1983–1993]
• 260 — 1980–1981 [4-Cyl. 2.1L: 1980–1981]
• 740 — 1985–1992 [4-Cyl. 2.3L: 1985–1992]
• 760 — 1984–1990 [4-Cyl. 2.3L: 1984–1990]
• 780 — 1989–1991 [4-Cyl. 2.3L: 1989–1991]
• 940 — 1991–1994 [4-Cyl. 2.3L: 1991–1994]
• 960 — 1992 [6-Cyl. 2.9L: 1992]

Cross-references (full)

• Gates: 33616
• Carquest: 30730
• Dayco: 82511
• Fel-Pro: 35278
• General Motors: 3522626, 3522676
• Ideal Tridon: 30985
• McCord: 74-0145
• NAPA: 1091
• Pep Boys: 35346
• Robertshaw: R96
• Standard Thomson: 1091
• Volvo Cars: 13174669, 13979117
• Stant equivalents: 25278, 30985, C78

Sources

1. Stant Thermostats, Gaskets, Caps – 1928 through 1994 catalog (scan on Internet Archive): https://archive.org/details/StantThermostatsGasketsCaps1928Through1994OCR637Pages — part-number index ("Make / Year(s)" table at the back of the catalog) and application pages (PDF pages 337, 338, 339, 340, 343, 623, 624). Every catalog line pairs "Thermostat Seal 25278" with "Thermostat Seal (1 Pack) 27278".
2. PartsHawk – Gates 33616 (interchange lists Stant 27278; style and dimensions): https://partshawk.com/gates-33616-engine-coolant-thermostat-seal.html
3. PartsHawk – Stant 27278 (fitment list): https://partshawk.com/stant-27278-engine-coolant-thermostat-seal.html
4. KaKaPart – Stant 27278 application table (Cadillac 1985–1993 V8, Volvo 122/240/740/760/780/940/960): http://www.kakapart.com/parts/stant-27278.html
5. yoyopart – GM 3522626 interchange (Gates 33616 = Stant 27278 / 25278): http://www.yoyopart.com/oem/12281258/gm-3522626.html

Ask Don