GM Lumina/Silhouette/Transport APVs 1990-1999 Repair Guide



The cooling system includes a radiator and recovery sub-system, cooling fan, thermostat and housing, water pump, and serpentine belt.

The operation of the cooling system requires proper functioning off all components. Coolant is drawn from the radiator by the water pump, circulated through coolant jackets in the engine block, intake manifold, and cylinder heads, and then directed back to the radiator where it is cooled. Coolant should be kept at a 50% solution to maintain an effective level of anti-rust and anti-corrosive properties, as well as protection against freezing and overheating.

A cross-flow aluminum radiator is used. Tanks in this type radiator are located to the right and left of the core instead of above and below. The radiator also has an oil cooler with inlet and outlet fittings for transaxle fluid circulation.

The core is made of aluminum and uses large tubes that resist plugging. The tanks are made of plastic and are attached to the core by the use of clinched tabs, The clinched tabs can be bent if the tank needs to be removed from the core.

A high temperature rubber gasket is used to seal the mating surface between the core and the tanks. The gasket MUST be replaced with the removal of the tanks.

The aluminum radiator uses a two piece drain cock and rubber seal. The drain cock is serviceable.

See Figures 1 and 2

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Fig. Fig. 1: Exploded view of a typical aluminum radiator, including the coolers and tanks.

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Fig. Fig. 2: Side view of aluminum radiator showing the drain cock location at the bottom of the tank.


  1. Disconnect the negative battery cable.
  3. Drain and recycle the engine coolant into a suitable container.

Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine 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 quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

See Figures 3 and 4

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Fig. Fig. 3: Top engine view of radiator; the fan assembly will have to be removed to remove the radiator.

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Fig. Fig. 4: Under vehicle view of the radiator. Note the trans cooler lines and flex connections; they will have to be disconnected to remove the radiator.

  1. Remove the engine forward strut bracket at the radiator, then swing the strut rearward. Make sure to loosen the bolt before swinging the strut, to prevent ripping the rubber bushing.

See Figure 5

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Fig. Fig. 5: Engine strut-to-radiator assembly mounting

  1. Disconnect the forward lamp harness from the fan frame and unplug the fan connector. Remove the fan and frame assembly by removing the fan attaching bolts. On some applications, a Low Coolant Module needs to be unplugged and removed also.

See Figures 6, 7 and 8

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Fig. Fig. 6: This left side bolt holds the cooling fan in place; the left and right side bottom bolts will have to be removed to remove the fan.

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Fig. Fig. 7: Unfasten the bottom bolts that secure the fan

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Fig. Fig. 8: Some vehicles have a low coolant module that must be removed

  1. Scribe the hood latch installed location for reinstallation, then remove the hood latch from the radiator support.
  3. Disconnect the coolant hoses from the radiator and coolant recovery tank hose from the radiator neck.

See Figures 9, 10 and 11

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Fig. Fig. 9: Using a pair of slip joint pliers to release and move the hose clamp. There are special pliers made for this purpose, and for applications that are more difficult.

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Fig. Fig. 10: Slide the clamp back, away from the neck of the radiator

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Fig. Fig. 11: Disconnect the upper hose from the radiator neck

  1. Disconnect and plug the transaxle cooler lines.
  3. Remove the radiator-to-radiator support attaching bolts and clamps.

See Figure 12

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Fig. Fig. 12: Unfasten the retainers, then remove the top radiator cover

  1. Lift the radiator out of the vehicle. If the lower mounting pads stick to the radiator during removal, the pads must be placed back in the lower radiator frame for installation of a new radiator.

If the old radiator is being replaced with a new one, transfer the fittings from the old to the new radiator.

See Figures 13, 14 and 15

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Fig. Fig. 13: Lift the radiator up and out of the vehicle. The bottom hose (A) is disconnected from the engine; trans cooler line (B) is disconnected at the rubber hose; and trans cooler line (C) is left connected at radiator.

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Fig. Fig. 14: Radiator removed from vehicle; note the trans cooler lines and lower hose are still attached to radiator. Where clearance allows, this is an easier removal

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Fig. Fig. 15: These radiator fins are clogged by debris; this can cause over-heating and coolant loss. Check and clean the radiator as part of a regular maintenance schedule

To install:
  1. Place the radiator in the vehicle, locating the bottom of the radiator into the lower mounting pads.

Try to maintain the location of the air baffles and seals; they help direct the airflow through the radiator.

See Figure 16

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Fig. Fig. 16: Exploded view of the air baffles and radiator air seals

  1. Install the radiator-to-radiator support attaching clamp and bolts. Tighten to 89 inch lbs. (10 Nm).
  3. Unplug and connect the cooler lines for the transaxle, be sure to check the fluid level upon completion.
  5. Install the coolant hoses to the radiator and the recovery hose to the neck.
  7. Replace the hood latch, aligning it to the scribed mark on the radiator frame. Tighten the bolts to 18 ft. lbs. (25 Nm).
  9. Install the fan and frame assembly, tighten the radiator attaching bolts, route the forward lamp harness to the fan frame and plug in the fan connector.
  11. If equipped, install and reconnect the Low Coolant Module sensor.
  13. Swing the engine front strut and brace forward, until brace the contacts the radiator support. Install the brace-to-radiator support attaching bolts and tighten to 37 ft. lbs. (50 Nm).
  15. Refill the engine cooling system.
  17. Connect the negative battery cable and check for leaks.