Description
This radiator cap fits the Honda Acty Truck HA3, HA4 (1990-1999). It holds cooling system pressure so the coolant boiling point stays high.
In Stock - ships from our California (USA) warehouse
Fast, reliable delivery - no overseas backorder wait.
Vehicle Fitment & Compatibility
Confirm your chassis code against the table below before ordering.
100% Fitment Guarantee
Not sure about fit? Add your chassis/VIN number at checkout and we confirm it before we ship. If a part does not fit your Acty, we exchange it or refund you in full.
Signs you need this radiator cap
- Overheating or coolant loss
- A cap that will not hold pressure
- A corroded or weak cap seal
- Coolant in the reserve but a low radiator
Features & Function
- Holds correct cooling system pressure
- Correct rating for the Acty radiator
- Raises the coolant boiling point
Installation Specifications
- Difficulty: Easy.
- Estimated time: a couple of minutes.
- Required tools: No tools.
Oiwa Garage Tech Note
"Only open or replace the cap on a cold engine. A weak cap is a cheap and common cause of mystery overheating on these trucks - rule it out first."
Frequently Asked Questions
How do I test the radiator cap?
A weak cap causes overheating and coolant pushed into the reserve. On a cold engine, check the seal for cracks or corrosion; a proper pressure test on the cap confirms whether it holds.
Do I need to bleed the cooling system after?
Yes. Refill and bleed the air out so the system cools properly and the engine does not overheat.
Fitment verified by the Kei truck specialists at Oiwa Garage ยท Listing updated June 2026.