I am replacing my water pump on 1990 E250/ 5.8 . I forgot which hose is heater and which is the bypass connection on pump? :runaround:

Normally the heater goes to the heater,the bypass is a short hose that goes to the front of the engine.

5.0L and 5.8L Engines
1989-95 MODELS
See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11

Drain the cooling system.
https://www.autozone.com/images/upper_left.gifhttps://www.autozone.com/images/grey_line.gifhttps://www.autozone.com/images/upper_right.gifhttps://www.autozone.com/images/clearpixel.gifhttps://www.autozone.com/images/clearpixel.gifCAUTIONhttps://www.autozone.com/images/clearpixel.gifWhen draining the coolant, keep in mind that cats 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. Coolant should be reused unless it is contaminated or several years old. https://www.autozone.com/images/clearpixel.gifhttps://www.autozone.com/images/clearpixel.gifhttps://www.autozone.com/images/lower_left.gifhttps://www.autozone.com/images/grey_line.gifhttps://www.autozone.com/images/lower_right.gif
If necessary, remove the air cleaner assembly, intake duct and crankcase ventilation hose.
Remove the radiator.
Remove the drive belt, fan shroud, fan clutch and pulley.
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Fig. 1: Remove the cooling fan-to-clutch bolts

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Fig. 2: Remove the clutch and fan assembly from the engine compartment

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Fig. 3: Remove the water pump pulley


Disconnect the heater hose, radiator hose and by-pass hose at the water pump.
Remove the A/C compressor/power steering pump bracket from the cylinder head and water pump water pump stud bolt after disengaging the A/C and power steering systems.
Remove the bolts securing the water pump to the front cover and remove the water pump and gasket.
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Fig. 4: Loosen the heater hose and bypass hose clamps ...

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Fig. 5: ... and disconnect the hoses from the pump

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Fig. 6: Loosen the lower radiator hose clamp

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Fig. 7: Disconnect the radiator hose from the water pump

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Fig. 8: Loosen the A/C compressor/power steering pump bracket-to-water pump retainers

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Fig. 9: Slide the bracket forward to disengage it from the studs on the pump

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Fig. 10: Loosen the water pump mounting bolts

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Fig. 11: Remove the water pump from the engine compartment

To install:

Clean the gasket mating surfaces.
If installing the old water pump, check it for damage
Coat a new gasket with sealer and install the water pump. Tighten the bolts to 15-21 ft. lbs. (20-28 Nm).
Connect the heater hose and by-pass hose at the water pump.
Connect the A/C and power steering pump accessories and bracket to the cylinder head and water pump stud.
Install the water pump pulley, fan shroud, fan clutch and drive belt.
Fill and bleed the cooling system.
If removed, install the air cleaner assembly, intake duct and crankcase ventilation hose.

Heres what you need to know courtesy of autozone.com