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BMW Coupes and Sedans 1970-1988 Repair Guide



See Figures 1, 2, 3, 4 and 5

Worn hoses may feel spongy, brittle and discolored. The lower hose may be permanently narrowed at one point from suction, or may appear frayed or cracked. In contrast, new hoses will be springy and pliable yet firm. The rubber surface will be solid and smooth, and there will be no evidence of string reinforcements showing through.

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Fig. Fig. 1: Cracks at the end of this hose indicate an old hose that has hardened. The reinforcing cords have most likely broken and will fail soon

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Fig. Fig. 2: If a hose clamp is tightened too much, it can cause an older hose to weaken. This hose has torn and separated

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Fig. Fig. 3: Hoses should be firm to the touch; a soft or spongy hose is a weak hose. Swollen ends are one indication of a soft, weakened hose


  1. Put a bucket with at least a 2 gallon capacity under the radiator draincock, if equipped, or under the radiator end of the lower hose.
  3. Open the draincock, or loosen the hose clamp and carefully slide the bottom hose off the radiator, and allow the coolant to flow out.

When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could 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. Coolant should be reused unless it is contaminated or several years old.

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Fig. Fig. 4: Debris such as rust and scale can ruin a hose quickly. This is another reason why a regular coolant flush and change is important

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Fig. Fig. 5: Coolant hoses-2002 model

  1. If a heater hose is being removed/replaced, turn the rotary heater control to WARM and allow any coolant contained in the heater core and hoses to drain out.
  3. Loosen the clamps at both ends of the hose(s). Work the hose ends off the radiator or heater core and engine block connections.
  5. Install the new hose in reverse order. If the hose has certain bends molded into it, make sure to position such that crimping is prevented. Install new hose clamps onto the hose from both ends before sliding hose ends onto the fittings. Make sure hoses slide all the way onto the connectors.
  7. Tighten the clamps securely, then refill the cooling system as described later in this section.