Joash was seven years old when he became king; he was king for forty years in Jerusalem. His mother's name was Gazelle (Zibiah). She was from Beersheba.
He got the priests and Levites together and said, "Circulate through the towns of Judah every year and collect money from the people to repair The Temple of your God. You are in charge of carrying this out."
Then the king called in Jehoiada the chief priest and said, "Why haven't you made the Levites bring in from Judah and Jerusalem the tax Moses, servant of GOD and the congregation, set for the upkeep of the place of worship? You can see how bad things are--wicked Queen Athaliah and her sons let The Temple of God go to ruin and took all its sacred artifacts for use in Baal worship."
Whenever the Levites brought the chest in for a royal audit and found it to be full, the king's secretary and the official of the chief priest would empty the chest and put it back in its place. Day after day they did this and collected a lot of money.
The king and Jehoiada gave the money to the managers of The Temple project; they in turn paid the masons and carpenters for the repair work on The Temple of GOD.
When they had finished the work, they returned the surplus money to the king and Jehoiada, who used the money for making sacred vessels for Temple worship, vessels for the daily worship, for the Whole-Burnt-Offerings, bowls, and other gold and silver liturgical artifacts. Whole-Burnt-Offerings were made regularly in The Temple of GOD throughout Jehoiada's lifetime.
Things went from bad to worse; they deserted The Temple of GOD and took up with the cult of sex goddesses. An angry cloud hovered over Judah and Jerusalem because of this sin.
Then the Spirit of God moved Zechariah son of Jehoiada the priest to speak up: "God's word: Why have you deliberately walked away from GOD's commandments? You can't live this way! If you walk out on GOD, he'll walk out on you."
But they worked out a plot against Zechariah, and with the complicity of the king--he actually gave the order!--they murdered him, pelting him with rocks, right in the court of The Temple of GOD.
That's the thanks King Joash showed the loyal Jehoiada, the priest who had made him king. He murdered Jehoiada's son. Zechariah's last words were, "Look, GOD! Make them pay for this!"
A year or so later Aramean troops attacked Joash. They invaded Judah and Jerusalem, massacred the leaders, and shipped all their plunder back to the king in Damascus.
The Aramean army was quite small, but GOD used them to wipe out Joash's large army--their punishment for deserting GOD, the God of their ancestors. Arameans implemented God's judgment against Joash.
They left Joash badly wounded and his own servants finished him off--it was a palace conspiracy, avenging the murder of the son of Jehoiada the priest. They killed him in his bed. Afterward they buried him in the City of David, but he was not honored with a grave in the royal cemetery.
The story of his sons, the many sermons preached to Joash, and the account of his repairs on The Temple of God can be found contained in the commentary on the royal history. Amaziah, Joash's son, was the next king.