Engine Cooling System: Overhaul Nissan Altima L31

Disassembly

1. Remove fan blade.
2. Remove fan motors from fan shroud.

Assembly

Assembly is in the reverse order of disassembly.

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1. Check that there is no dirt or damage on the valve seat of the radiator cap negative pressure valve.
2. Check that there are no abnormalities in the opening and closing conditions of the negative-pressure valve.
3. Pull the negative-pressure valve to open it.
4. Check that it closes completely when released.
5. Check the radiator cap relief pressure specifications. Standard: 78 - 98 kPa (0.78 - 0.98 bar, 0.8 - 1.0 kg/cm 2 , 11 - 14 psi) Limit: 59 - 98 kPa (0.59 - 0.98 bar, 0.6 - 1.0 kg/cm 2 , 9 - 14 psi)
6. When installing the radiator cap on the tester, apply water or coolant to the cap seal surface.
7. Replace the radiator cap if there is an abnormality in the negative-pressure valve, or if the open-valve pressure is outside of the standard specifications.

1. Remove fan blade.
2. Remove fan motor from fan shroud.

1. Assemble in the reverse order of disassembly.

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1. Remove undercover, using power tools.
2. Remove suspension member stay.
3. Drain coolant from radiator. Refer to «Changing Engine Coolant»(ref-183495-S21164635392005081400000) .
4. Remove radiator shrouds.
5. Remove drive belts.
6. Remove cooling fan.
7. Remove water drain plug on water pump side of cylinder block.
8. Remove chain tensioner cover and water pump cover.
9. Remove the chain tensioner assembly. Pull the lever down and release the plunger stopper tab. Insert the stopper pin into the tensioner body hole to hold the lever and keep the stopper tab released Insert the plunger into the tensioner body by pressing the timing chain slack guide. Keep the slack guide pressed and hold the plunger in by pushing the stopper pin deeper through the lever and into the tensioner body hole Make a gap between water pump gear and timing chain, by turning the crankshaft pulley 20° counter-clockwise.
10. Remove the three water pump mounting bolts.
11. Install two bolts into the water pump body bolt holes.
12. Tighten the two bolts by turning half turn alternately until they reach timing chain rear case. In order to prevent damage to the water pump or timing chain rear case, do not tighten one bolt continuously. Always turn each bolt a half turn each time.
13. Lift up the water pump and remove it. When lifting up on the water pump, do not allow the water pump gear to hit the timing chain.

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1. Check for badly rusted or corroded water pump body assembly.
2. Check for rough operation due to excessive end play.

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1. Apply engine oil and coolant to the O-rings as shown.
2. Install the water pump. Do not allow cylinder block to interfere with the O-rings when installing the water pump.
3. Before installing, remove all traces of RTV Silicone Sealant from mating surface of water pump cover and chain tensioner cover using a scraper. Also remove traces of RTV Silicone Sealant from the mating surface of the front cover.
4. Apply a continuous bead of Genuine RTV Silicone Sealant, or equivalent, to mating surface of chain tensioner cover and water pump cover. Refer to «RECOMMENDED CHEMICAL PRODUCTS AND SEALANTS»(ref-177331-S01572020272005052600000) .
5. Return the crankshaft pulley to its original position by turning it 20° clockwise.
6. Install the timing chain tensioner, then remove the stopper pin. When installing the timing chain tensioner, engine oil should be applied to the oil hole and tensioner. After starting engine, let idle for three minutes, then rev engine up to 3,000 rpm under no load to purge air from the high-pressure chamber of the chain tensioner. The engine may produce a rattling noise. This indicates that air still remains in the chamber and is not a matter of concern.
7. Installation is in the reverse order of removal.

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1. Remove undercover.
2. Drain coolant from radiator. Refer to «Changing Engine Coolant»(ref-183495-S21164635392005081400000) .
3. Remove drive belts.
4. Remove water drain plug on water pump side of the engine.
5. Disconnect lower radiator hose.
6. Remove engine coolant inlet and thermostat assembly. Do not disassemble engine coolant inlet and thermostat. Replace them as a unit, if necessary.

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1. Check valve seating condition at ordinary room temperatures. It should seat tightly.
2. Check valve opening temperature and maximum valve lift.
3. Then check if valve closes at 5°C (9°F) below valve opening temperature.

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1. Install thermostat with jiggle valve facing upward. After installation, run engine for a few minutes, and check for leaks. Be careful not to spill coolant over engine compartment. Use a rag to absorb coolant.
2. Installation is in the reverse order of removal.