Inspect the condition of the radiator and heater hoses periodically. Early spring and at the beginning of the fall or winter, when you are performing other maintenance, are good times. Make sure the engine and cooling system are cold. Visually inspect for cracking, rotting or collapsed hoses, replace as necessary. Run your hand along the length of the hose. If a weak or swollen spot is noted when squeezing the hose wall, replace the hose.
Don't overlook the smaller hoses conducting coolant around the outside of the engine block, carburetor or throttle body. Honda recommends that all hoses be thoroughly inspected every 30,000 miles (48,000 km).
Replacing hoses requires draining the cooling system. This potentially messy job involves working under the car and handling antifreeze, a slippery, smelly, stain-making chemical. Have a large drain pan or bucket available along with healthy supply of rags. Be prepared to deal with fluid spills immediately. See the list of Do's and Don'ts in the beginning of this section for other hints.
- Drain the cooling system. This is always done with the engine cold. Attempting to drain hot coolant is very foolish; you can be badly scalded. Honda engines and radiators may be drained by opening the drain cock at the base of the radiator. If the coolant is drained in this fashion, remember to close the draincock before adding coolant again.
An alternative method is:
- Remove the radiator cap.
- Position the drain pan under the point where the lower radiator hose hooks to the radiator. Loosen the clamp on the hose and slide it back so it's out of the way.
- Gently break the grip of the hose on its fitting by twisting or prying with a suitable tool. Do not exert too much force or you will damage the radiator fitting. As the hose loosens, you can expect a gush of fluid-be ready.
- Remove the hose end from the radiator and direct the hose into the drain pan. You now have fluid running from both the hose and the radiator. When the system stops draining, proceed with replacement of the damaged hose.
- Loosen the hose clamps on the damaged hose with a screwdriver and slide the clamps either off the hose altogether or in toward center.
- Break the grip of the hose at both ends by prying it free with a suitable tool or by twisting it with your hand.
- Remove the hose.
- Install a new hose. A small amount of soapy water or window cleaner on the inside of the hose end will ease installation.
Radiator hoses should be routed with no kinks and, when installed, should be in the same position as the original. If other than specified hose is used, make sure it does not rub against either the engine or any other component while the engine is running, as this may wear a hole in the hose. Contact points may be insulated with a piece of sponge or foam; plastic wire ties are particularly handy for this job.
- Slide the hose clamps back into position and re-tighten. When tightening the clamps, tighten them enough to seal in the coolant but not so much that the clamp cuts into the hose or causes it internal damage. If a clamp shows signs of any damage (bent, too loose, hard to tighten, etc.) now is the time to replace it. A good rule of thumb is that a new hose is always worth new clamps.
- Reinstall the lower radiator hose and secure its clamp.
- Fill the system with coolant. Honda strongly recommends that the coolant mixture be a 50/50 mix of antifreeze and water. This mixture gives best combination of anti-freeze and anti-boil characteristics for year-round driving.
Cold weather anti-freezing protection is best at the 50/50 mixture. If the mixture contains 40 percent water or less, engine cooling is impaired. Do not use additional rust inhibitors or other such products. The cooling system may be damaged by incompatible fluids.
- When adding coolant to the radiator and or the coolant reservoir (jug), take great care to prevent spillage onto the fuse and relay panel under the hood. Should spillage occur, wipe it off immediately.
- Loosen the bleeder bolt. This is usually located on the thermostat housing.
- Replace and tighten the radiator cap. Start the engine and check visually for leaks. Allow the engine to warm up fully and continue to check your work for signs of leakage. A very small leak may not be noticed until the system develops internal pressure. Leaks at hose ends are generally clamp related and can be cured by snugging the clamp. Larger leaks may require removing the hose again. To do this, you must wait until the engine has cooled down, generally a period of hours. NEVER UNCAP A HOT RADIATOR! The bleeder bolt may be tightened after a steady stream of coolant comes out with no bubbles. After all leaks are repaired, check the coolant level in the radiator (with the engine cold) and top up as necessary.