The City Manager, at least sixty days prior to the beginning of each budget year, shall submit to the Council an operating budget estimate and an explanatory budget message after consultation with the head of each department or agency who shall fully cooperate with the City Manager in assisting in the preparation of the budget estimate and message. In addition, the City Manager shall prepare, at such time as Council directs, descriptions and budget estimates of needed capital expenditures. The Department of Finance shall furnish statements of balances available for appropriation, estimates of probable revenues from all sources, and expenditure estimates for debt service and other fixed items. The City Manager shall prepare, revise and adjust the budget estimates for the Council as may be required in order to produce a balanced budget.