The 1966 Triumph TR4A has 45 cooling system parts with verified fitment on this page — 6 part types and 11 brands, covering the 2.1L L4 engine. Each part includes a manufacturer part number and application notes.
The cooling system system on the 1966 Triumph TR4A keeps operating temperature in the narrow band the engine was designed for, from radiator and water pump to thermostat and hoses. The largest groups are Coolant / Antifreeze (16 parts), Thermostat (16 parts) and Radiator Hose (5 parts). The other 3 part types cover the remaining 8 parts.
Every part on this page is matched to the 2.1L L4 — the only engine offered in the 1966 Triumph TR4A.
The most listed brands for 1966 Triumph TR4A cooling system parts are MOTORAD (17 parts), PEAK (7 parts) and PRESTONE (5 parts), plus 8 more brands. Quality grades include Standard Replacement, Economy and Premium.
9 parts on this 1966 Triumph TR4A page carry a "Popular" badge — the source catalog's flag for options frequently chosen for this vehicle — including FVP MV5050GAL (Coolant / Antifreeze) and GATES 20801 (Radiator Hose). Click any part number to see every vehicle that part fits.
Coolant / Antifreeze
Compatible With All Colors
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| PRESTONE | AF3055 | 🇺🇸 US | Prime YellowAll Vehicles | View on Amazon |
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| FVP Popular | MV5050GAL | 🇺🇸 US | Extended LifeAll Makes / All Models | View on Amazon |
| PRESTONE Popular | AF3100 | 🇺🇸 US | Prime Yellow - All VehiclesExtended Life | View on Amazon |
| PEAK | BQA1GAL | 🇺🇸 US | Blue Mountain Long LifeAll Vehicle | View on Amazon |
| VALVOLINE | 719009 | 🇺🇸 US | Multi-Vehicle Yellow1 Gallon | View on Amazon |
Heavy Duty
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VALVOLINE Popular | ZXG051 | 🇺🇸 US | G05 Yellow1 Gallon | View on Amazon |
Premium
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| PRESTONE Popular | AF2100 | 🇺🇸 US | All Vehicles10yr/300k mi | View on Amazon |
| PEAK | PKP1GAL | 🇺🇸 US | All Vehicles Antifreeze1 Gallon | View on Amazon |
| PEAK | PXA1GAL | 🇺🇸 US | Global Lifetime1 Gallon | View on Amazon |
| PRESTONE | AFMAX | 🇺🇸 US | Max Universal1 Gallon | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| FVP | GREEN5050GAL | 🇺🇸 US | Low Silicate Blend1 Gallon | View on Amazon |
| PEAK | BMA1GAL | 🇺🇸 US | Blue Mountain Conventional Green1 Gallon | View on Amazon |
| PEAK | RUA1GAL | 🇺🇸 US | Conventional Green1 Gallon | View on Amazon |
| PEAK | FFA1GAL | 🇺🇸 US | Full Force Conventional Green1 Gallon | View on Amazon |
| PEAK | SEP1GAL | 🇺🇸 US | Sierra Conventional Green Concentrate Low Toxic Option1 Gallon | View on Amazon |
| PRESTONE | AF3300 | 🇺🇸 US | Prime Conventional Green 1 Gallon | View on Amazon |
This table covers the engine coolants and antifreeze formulations specified for this cooling system. Typical signs include a rising temperature gauge, rusty or sludged coolant, or a heater that blows cold. Use the chemistry named in the notes. Mixing silicate, OAT and HOAT formulas can gel in the radiator.
16 Coolant / Antifreeze parts for the 1966 Triumph TR4A come from 4 brands — PEAK, PRESTONE, FVP and 1 other brand. The "Popular" part is FVP MV5050GAL.
In the Compatible With All Colors grade, PRESTONE supplies 1 part: grouped under the catalog's "Compatible With All Colors" designation — the notes column spells out what sets them apart. A representative part number is PRESTONE AF3055.
The Economy section lists 4 options from FVP, PRESTONE, PEAK and 1 other brand — the catalog's value-priced group. FVP MV5050GAL is listed in this group.
In the Heavy Duty grade, VALVOLINE supplies 1 part: rated for severe service. A representative part number is VALVOLINE ZXG051.
In the Premium grade, PRESTONE and PEAK supply 4 parts: a step above OE specification in materials, tolerances or warranty terms. A representative part number is PRESTONE AF2100.
In the Standard Replacement grade, PEAK, FVP and PRESTONE supply 6 parts: built to original-equipment specification. A representative part number is FVP GREEN5050GAL.
Cooling System Tester Adapter
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| ACDELCO | 12A01 | 🇺🇸 US 🇨🇦 CA | ProfessionalIncluded In Tester | View on Amazon |
| MOTORAD | 3003 | 🇺🇸 US | StandardIncluded In Tester Kit | View on Amazon |
This table covers the adapters used to pressure-test this cooling system.
2 Cooling System Tester Adapter parts for the 1966 Triumph TR4A come from 2 brands — ACDELCO and MOTORAD.
Listed part numbers: ACDELCO 12A01 and MOTORAD 3003.
Radiator Cap
Locking Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| MOTORAD | ST7 | 🇺🇸 US | Safety Lever | View on Amazon |
| SKP | SKST7 | 🇺🇸 US | with Safety Lever | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| CALORSTAT | RC0067 | 🇺🇸 US | PerformanceIncludes Seal | View on Amazon |
| MOTORAD | T7 | 🇺🇸 US | Standard | View on Amazon |
This table covers the caps that hold system pressure at the radiator or reservoir neck. Typical signs include a leak at the neck, a cap that will not hold pressure, or a missing tether. Match the pressure rating or thread in the notes — radiator, reservoir and fuel caps are not interchangeable.
4 Radiator Cap parts for the 1966 Triumph TR4A come from 3 brands — MOTORAD, SKP and CALORSTAT.
In the Locking Replacement grade, MOTORAD and SKP supply 2 parts: grouped under the catalog's "Locking Replacement" designation — the notes column spells out what sets them apart. A representative part number is MOTORAD ST7.
Standard Replacement: 2 parts, from CALORSTAT and MOTORAD. A representative part number is CALORSTAT RC0067.
Listed part numbers: MOTORAD ST7, SKP SKST7 and CALORSTAT RC0067, plus the other parts above.
Radiator Hose
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| ACDELCO | 31608 | 🇺🇸 US 🇨🇦 CA | Gold / ProfessionalFlexible | View on Amazon |
| GATES | 25249 | 🇺🇸 US | Flexible | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Popular | 20801 | 🇺🇸 US | Molded | View on Amazon |
| ACDELCO | 20075S | 🇺🇸 US 🇨🇦 CA | Professional / GoldMolded | View on Amazon |
| CONTINENTAL | 60425 | 🇺🇸 US | Molded | View on Amazon |
This table covers the upper, lower and connecting hoses between radiator, engine and reservoir. Typical signs include swelling, cracks, a soft spot, or a leak at a clamp. Replace adjacent aged hoses while the system is drained — they share the same heat cycle.
5 Radiator Hose parts are listed for the 1966 Triumph TR4A, from ACDELCO, GATES and CONTINENTAL. GATES 20801 carries the "Popular" badge.
Economy: 2 parts, from ACDELCO and GATES. A representative part number is ACDELCO 31608.
The Standard Replacement section: 3 options from GATES, ACDELCO and CONTINENTAL. GATES 20801 is listed in this group.
This group includes GATES 20801, ACDELCO 31608 and GATES 25249 and the remaining parts above.
Thermostat
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| MOTORAD | 300160 | 🇺🇸 US | Economy | View on Amazon |
| MOTORAD | 300195 | 🇺🇸 US | Economy | View on Amazon |
| MOTORAD | 300180 | 🇺🇸 US | Economy | View on Amazon |
Heavy Duty
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| MOTORAD | 5200160 | 🇺🇸 US | Ultra Stat | View on Amazon |
| MOTORAD | 5200180 | 🇺🇸 US | Ultra Stat | View on Amazon |
Performance
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| MOTORAD Popular | 2000160 | 🇺🇸 US | High Flow | View on Amazon |
| MOTORAD Popular | 2000180 | 🇺🇸 US | High Flow | View on Amazon |
| MOTORAD | MRD100 | 🇺🇸 US | Racing Thermostat | View on Amazon |
Premium
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| MOTORAD | 7200180 | 🇺🇸 US | Fail-Safe | View on Amazon |
| MOTORAD | 7200160 | 🇺🇸 US | Fail-Safe | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| MOTORAD Popular | 200195 | 🇺🇸 US | Standard | View on Amazon |
| MOTORAD Popular | 200180 | 🇺🇸 US | Standard | View on Amazon |
| BECK/ARNLEY | 1430156 | 🇺🇸 US | Alternate TemperatureGasket/Seal Not Included | View on Amazon |
| BECK/ARNLEY | 1430149 | 🇺🇸 US | OE TemperatureGasket/Seal Not Included | View on Amazon |
| BECK/ARNLEY | 1430131 | 🇺🇸 US | Alternate TemperatureGasket/Seal Not Included | View on Amazon |
| MOTORAD | 200160 | 🇺🇸 US | Standard | View on Amazon |
This table covers the thermostats that open the coolant circuit at the specified temperature. Typical signs include slow warm-up, a gauge that climbs in traffic, or heat that never quite arrives. Replace the housing gasket with the thermostat and bleed the system so a trapped air pocket does not cook the new part.
16 Thermostat parts are listed for the 1966 Triumph TR4A, from MOTORAD and BECK/ARNLEY. MOTORAD 2000160 carries the "Popular" badge.
Economy: 3 parts, from MOTORAD. A representative part number is MOTORAD 300160.
The Heavy Duty section: 2 options from MOTORAD. MOTORAD 5200160 is listed in this group.
In the Performance grade, MOTORAD supplies 3 parts: engineered beyond original-equipment specification. A representative part number is MOTORAD 2000160.
The Premium section: 2 options from MOTORAD. MOTORAD 7200180 is listed in this group.
The Standard Replacement section: 6 options from MOTORAD and BECK/ARNLEY. MOTORAD 200195 is listed in this group.
Thermostat / Thermostat Housing / Water Outlet Seal
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| BECK/ARNLEY | 0390001 | 🇺🇸 US | Thermostat Seal | View on Amazon |
| MOTORAD | MG38 | 🇺🇸 US | View on Amazon |
This table covers the seals at the thermostat housing and water outlet. Typical signs include a wet housing, a drip after sitting, or fluid flung off a rotating shaft. Fix the surface the seal rides on. A new seal on a grooved shaft will leak again.
2 Thermostat / Thermostat Housing / Water Outlet Seal parts for the 1966 Triumph TR4A come from 2 brands — BECK/ARNLEY and MOTORAD.
Listed part numbers: BECK/ARNLEY 0390001 and MOTORAD MG38.
Buying Cooling System Parts for a 1966 Triumph TR4A
On this vehicle, the cooling system system keeps operating temperature in the narrow band the engine was designed for, from radiator and water pump to thermostat and hoses.
- Confirm you have the 2.1L L4 engine — every part on this page is matched to it.
- Read the notes on each row for position, trim and spec qualifiers before you order.
- Where labor overlaps, replace the thermostat and refill with fresh coolant whenever you change a water pump or radiator; original hoses on an older vehicle are on borrowed time.
- Cross-reference the manufacturer part number against your old part or a service-manual listing.
Start with the largest groups on this page: Coolant / Antifreeze and Thermostat .
Frequently Asked Questions
How many cooling system parts fit the 1966 Triumph TR4A?
Our catalog currently lists 45 cooling system parts for the 1966 Triumph TR4A across 6 subcategories and 11 brands, covering the 2.1L L4 engine. Each part is matched to the engine(s) it fits.
What are the signs of cooling system problems on a 1966 Triumph TR4A?
Common symptoms include a rising temperature gauge in traffic, sweet-smelling steam, crusty deposits around hose clamps, or a heater that blows cold. If you notice any of these, identify the affected subcategory above and cross-reference the part numbers listed.
What should I replace at the same time?
Where labor overlaps, replace the thermostat and refill with fresh coolant whenever you change a water pump or radiator; original hoses on an older vehicle are on borrowed time.
What do the market flags (US, CA, MX) on each part mean?
They show the market for which the manufacturer published application data for that part — where the vehicle was first sold, not where the part was made. If your 1966 Triumph TR4A was originally sold in the US, the safest choice is a part marked for the US market.
How do I make sure a part fits my 1966 Triumph TR4A?
Every part on this page is matched to the 2.1L L4 engine. Then replace coolant with the exact specification the manufacturer calls for — mixing chemistries can gel and block small passages. The notes column carries position and trim qualifiers where they apply.
Other Parts for the 1966 Triumph TR4A
Cooling System Parts for Other Triumph TR4A Years
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