Mazda B-Series 1998-06

System Inspection


Checking The Radiator Cap

While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat. Worn caps should be replaced with new ones.

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Fig. Be sure the rubber gasket on the radiator cap has a tight seal

Clean Radiator Of Debris

Any time you have the hood open, glance at the coolant recovery tank to make sure it is properly filled. Top off the cooling system using the recovery tank and its markings as a guideline. If you top off the system, make a note of it to check again soon. A coolant level that consistently drops is usually a sign of a small, hard to detect leak, though in the worst case it could be a sign of an internal engine leak (blown head gasket/cracked block-... check the engine oil for coolant contamination). In most cases, you will be able to trace the leak to a loose fitting or damaged hose (and you might solve a problem before it leaves you stranded). Evaporating ethylene glycol antifreeze will leave small, white (salt like) deposits, which can be helpful in tracing a leak.

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Fig. Common cooling system components found on all models (not shown is the water pump)-3.0L equipped B Series Pick-up shown, other models are similar

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Fig. Coolant overflow tank full and low level measurements

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Fig. Pull the cap and suction tube out of the coolant overflow tank to top off the cooling system

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Fig. Fill the engine coolant overflow tank to the FULL line

At least annually or every 15,000 miles (24,000 km), all hoses, fittings and cooling system connections should be inspected for damage, wear or leaks. Hose clamps should be checked for tightness, and soft or cracked hoses should be replaced. Damp spots, or accumulations of rust or dye near hoses or fittings indicate possible leakage. These must be corrected before filling the system with fresh coolant. The pressure cap should be examined for signs of deterioration and aging. The fan belt and/or other drive belt(s) should be inspected and adjusted to the proper tension. Refer to the information on drive belts found earlier in this section. Finally, if everything looks good, obtain an antifreeze/coolant testing hydrometer in order to check the freeze and boil-over protection capabilities of the coolant currently in your engine. Old or improperly mixed coolant should be replaced.

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Fig. Checking antifreeze protection with an inexpensive tester

When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and are likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant may be reused unless it is contaminated or several years old.

At least once every 3 years or 36,000 miles (48,000 km), the engine cooling system should be inspected, flushed and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion. If the coolant has too much water, it won't protect against freezing.

If you experience problems with your cooling system, such as overheating or boiling-over, check the simple before expecting the complicated. Make sure the system can fully pressurize (are all the connections tight/is the radiator cap on properly, is the cap seal intact-). Ideally, a pressure tester should be connected to the radiator opening and the system should be pressurized and inspected for leaks. If no obvious problems are found, use a hydrometer antifreeze/coolant tester (available at most automotive supply stores) to check the condition and concentration of the antifreeze in your cooling system. Excessively old coolant or the wrong proportions of water and coolant will hurt the coolant's boiling and freezing points.

Periodically, clean any debris-leaves, paper, insects, etc.- from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.

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Fig. Periodically remove all debris from the radiator fins

Carefully straighten any bent radiator fins with a pair of needle-nosed pliers. Be careful; the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.