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How to Choose the Correct Radiator Cap

Radiator Cap Diagram

Did you know?

Cooling systems have an effect on everything from power to gas mileage and everything in between. When was the last time that you changed an oil filter? Added coolant or brake fluid? How about replaced your radiator cap?

Radiator caps are the most overlooked component of your cooling system and ironically the least expensive. Replacing your radiator cap regularly can save your customer money at the pump and save wear and tear on your cooling system overall. Caps have a seal that can wear away over time. Over time, your fuel costs will also increase.

*Measurements are reference only and may vary slightly with application.

*Matching EXISTING PSI is critical in selecting your radiator cap.

FILLER NECK WIDTH (outer dimension) FILLER NECK DEPTH PSI (lbs) FOR COOLANT RESERVOIR SYSTEMS OVERALL HEIGHT OVERALL DIAMETER NOTES PART #
32mm (inner dimension) 10mm 13 YES 0.68" 1.71" Upper seal RW0021-65
32mm (inner dimension) 10mm 16 YES 0.68" 1.71" Upper seal RW0021-66
32mm (inner dimension) 16 mm 13 YES .96” 1.77” Upper seal RW0021-6
32mm (inner dimension) 16 mm 16 YES .96” 1.77” Upper seal RW0021-23
32mm (inner dimension) 16 mm 26 YES 0.96" 1.77" Upper seal Z19210
2.2" .75” 4 NO 1” 2.3”  NO upper seal RW0021-11
2.2" .75” 7 NO 1” 2.3" NO upper seal RW0021-81
2.2" .75” 7 YES 1.20" 2.3" Upper seal Z17705
2.2" .75” 7 YES 1” 2.3” Upper seal RW0021-1
2.2" .75” 10 NO 0.96" 2.3" NO upper seal  RW0021-73
2.2" .75” 10 YES 0.96" 2.3" Upper seal RW0021-70
2.2" .75” 10 YES 0.96" 2.3" Upper seal RW0021-72
2.2" .75” 10 YES 1” 2.3” Upper seal RW0021-5
2.2" .75” 10 YES 2.3” 3.5” Massey Freguson Special RW0021-24
2.2" .75” 13 YES 1.20" 2.3" Upper seal Z17704
2.2" .75” 13 YES 1.4” 2.3” Lever Lift with upper seal RW0021-3
2.2" .75” 13 YES 1” 2.3" Upper seal RW0021-80
2.2" .75” 13 YES 1” 2.3” Upper seal RW0021-2
2.2" .75” 16 YES 1.20" 2.3" Upper seal Z17700
2.2" .75” 16 YES 1” 2.3” Vented  Drop Valve with upper seal RW0021-12
2.2" .75” 16 YES 1” 2.3” Upper seal RW0021-22
2.2" .75” 20 YES 0.96" 2.3" Upper seal RW0021-74
2.2" .75” 20 YES 1.14" 2.3" Upper seal Z19200
2.2" .75” 24 YES 1.14" 2.3" Upper seal Z19201
2.2" .75” 28 YES 1.14" 2.3" Upper seal Z19202
2.2" 1" 4 NO 1.2” 2.3” NO upper seal  RW0021-15
2.2" 1" 7 NO 1.2” 2.3” NO upper seal  RW0021-14
2.2" 1" 10 NO 1.4” 2.3” NO upper seal  RW0021-25
2.7” .75” 4 NO .96” 2.8” NO upper seal  RW0021-9
2.7” .75” 7 NO .96” 2.8” NO upper seal  RW0021-4
2.7” .75” 7 YES .96” 2.8” Upper seal RW0021-292B
2.7” .75” 10 NO .96” 2.8” NO upper seal  RW0021-40
2.7” .75” 15 NO 1" 2.8" NO upper seal  RW0021-77
2.7” .75” 15 YES .96” 2.8” Upper seal RW0021-294B
2.7” .75” 15 YES 1.12" 2.8" Upper seal Z17703
Click product link for more information   10   1.08" 3.11" Plastic cap threaded  RW0021-79
Click product link for more information   15   1.08" 3.11" Plastic cap threaded  RW0021-78
Click product link for more information   15   1.48" 2.54" Plastic cap threaded  RW0021-75
Click product link for more information   N/A   1 2.36" Surge tank cap RW0021-76

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