Honda Accord/Prelude 1984-1995 Repair Guide

Cooling System

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FLUID RECOMMENDATIONS



Use a quality, ethylene-glycol based engine coolant specifically recommended for use with vehicles utilizing aluminum engine parts that are in contact with the coolant. Note that some coolants, although labeled for use in such vehicles, actually may fail to provide effective corrosion protection. If necessary, consult your dealer or a professional mechanic. Honda's engine warranty does not cover damage caused by the use of improper coolant.

It is best to buy a top-quality product that is known to work effectively under such conditions. Always add coolant mixed with the proper amount of clean water. Never add either water or coolant alone. Mix the coolant at a 50/50 ratio in the amount needed. Consult the chart on the antifreeze container and utilize the proportions recommended for the lowest expected temperatures in your area.

LEVEL CHECK



See Figures 1, 2 and 3


WARNING
Keep hands and clothing away from the radiator fans. On some vehicles, the fans may start automatically up to 15 minutes after the engine is shut OFF!

The coolant level should be checked with the engine at normal operating temperature. To check the coolant level, simply see if the coolant is up to the FULL line on the expansion tank. On some models, the expansion tank is buried in the front fender well. Lift the lid of the tank, then remove the plastic dipstick. Wipe the dipstick, then check the coolant level as you would check the engine oil. The radiator cap should be removed only for the purpose of cleaning or draining the system.



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Fig. Fig. 1: Fill the expansion tank to the MAX line



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Fig. Fig. 2: Some coolant tanks have their own dipsticks

Add coolant to the expansion tank if the level is low, being sure to mix it with clean water. Never add cold water or coolant to a hot engine as damage to both the cooling system and the engine could result. If any coolant mixture should spill or splash onto painted surfaces, rinse it off immediately with plenty of clean water. The coolant will damage the paint.



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Fig. Fig. 3: Add coolant to the expansion tank if the level is low


CAUTION
The cooling system is under pressure when hot. Removing the radiator cap when the engine is warm or overheated will cause coolant to spill or spray out, possibly causing serious burns! The system should be allowed to cool for a period of hours before attempting removal of the radiator cap or hoses.

DRAIN AND REFILL



See Figures 4, 5, 6, 7 and 8


CAUTION
When draining coolant, keep in mind that cat and dogs are attracted by ethylene glycol antifreeze, and are quite 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 the coolant into a sealable container.

The radiator coolant should be changed at 36 month or 45,000 mile (72,000 km) intervals whichever comes first. Perform this maintenance only on a cold engine; overnight cold is best to avoid scalds.

  1. Remove the radiator cap. Just turn it, don't press down.
  2.  
  3. Slide a fluid catch pan under the radiator. Loosen the draincock at the base of the radiator and allow the coolant to drain. Honda engines are equipped with a drain bolt in the block as well, but these can be difficult to access. The drain is either under the exhaust manifold or above the oil filter. In either case, getting it loose almost always requires working from under the engine. An alternate method is to disconnect the lower radiator hose from the radiator.
  4.  
  5. Drain the coolant in the reservoir tank by unclipping and disconnecting the hose. If the tank is buried in the fender well, use a mechanical siphon or suction tool such as a turkey baster to draw out the fluid.
  6.  



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Fig. Fig. 4: Cooling system drain and bleed bolt locations; 1984-89 Accord and 1984-91 Prelude



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Fig. Fig. 5: Cooling system drain and bleed bolt locations; 1990-95 4-cylinder Accord and 1992-95 Prelude



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Fig. Fig. 6: Cooling system drain and bleed bolt locations on the V-6 Accord



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Fig. Fig. 7: A pair of pliers can be helpful for loosening the draincock on the radiator

  1. Mix a solution of 50 percent ethylene glycol (designed for use in aluminum engines) and 50 percent clean water. Use a stronger solution, only as specified on the antifreeze container (if the climate in your area demands it). Tighten the drain bolt(s) and double check them. Reinstall the lower radiator hose if it was disconnected.
  2.  
  3. Loosen the cooling system bleed bolt on the top of the thermostat housing. Fill the radiator with the coolant mixture. When coolant flows out of the bleed port in a steady stream without air bubbles, close the bolt and refill the radiator with coolant up to the base of the neck.
  4.  



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Fig. Fig. 8: Refill the system through the opening in the radiator

  1. To purge any air trapped in other parts of the cooling system, leave the radiator cap off and set the heater control to Hot. Start the engine and allow it to reach normal operating temperature; this means that the temperature gauge is in the normal range and the radiator fan has cycled on at least twice.
  2.  
  3. When the engine reaches normal operating temperatures, top off the radiator and keep checking until the level stabilizes. Refill the coolant reservoir to the FULL mark and make sure that the radiator cap is properly tightened.
  4.  

Fresh antifreeze has a cleansing effect in the passages. If the coolant has not been changed on schedule, the new coolant may dislodge sludge within the system. If the discoloration is extreme, the system may need to be drained a second time.

FLUSHING AND CLEANING THE SYSTEM



  1. Refer to the thermostat removal and installation procedures in Engine & Engine Overhaul and remove the thermostat from the engine.
  2.  
  3. Using a water hose, force fresh water into the thermostat housing opening, allowing the water to back-flush into the engine, heater and radiator. Flush the system until the water flowing from the radiator hose is clear.
  4.  
  5. After cleaning, reverse the removal procedures. Refill the cooling system with fresh coolant.
  6.  

 
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