HI NISSAN PULSAR Q 2004 MODEL 1600 HAS AN OVERHEATING PROBLEM I HAVE CHANGED THE THEMOSTAT, CLEAN RADIATOR, NEW WATER PUMP & BLEEDED THE COOLING SYSTEM, CHECK HEAD GASKET NO SIGNS OF BLOWEN HEAD & CHECK TO SEE IF THERE WAS ANY BLOCKAGE IN HEATER HOSES COULD YOU PLEASE TELL ME IF THERE IS A COMMON PROBLEM WITH THIS MODEL OR IF YOU CAN THINK OF ANYTHING ELSE I CAN DO

Some Nissans have a bleeder port to remove air from the system. I'm not sure where they are on your car. Sorry I can't give you the location. Am willing to check if you need me to.

Do the radiator fans work? Are the external cooling fins clean and unobstructed? Could the radiator flow be restricted? Do you have a head gasket that is leaking. Did you bleed out all of the air in the system? Is the radiator cap good?

1. The radiator cap if working correctly it will release pressure in the system provided the cap you have is the correct pressure setting. If you are having a problem with pressure then replace the cap with a new radiator cap with the correct pressure setting. Do not use a cap with a pressure setting other than the original equipment pressure spec. So you do not go to the parts store and buy any radiator cap on the shelf that fits because they come with different pressure ratings and some of these will be totally unsuitable for your car.

2. If the pressure valve is stuck in the "old" cap the pressure release system will not work.

3. Overheating
Air pockets in the cooling system can definitely cause overheating and can retard coolant flow through the system. If you are draining the radiator to replace the coolant or replacing the radiator you need to follow the correct procedures for bleeding air out of the system for that particular engine after coolant refilling. Some engines have bleeder screws on the cooling system to assist in the air bleeding procedure and some don't.

There are various causes for overheating so don't assume it will necessarily be solved by bleeding any remaining air from the cooling system and replacing the radiator cap with one that works.

Other causes can be...........
1. Faulty cooling system thermostat. (Replace the Thermostat)
2. Faulty water pump, especially if the impellers have corroded away or have disintegrated in the case of those design genius water pumps with plastic impellers. (Replace the water pump)

3. Cooling fans not working and if so the cause needs to be tracked. Check that your fans are kicking in. If the engine is overheating the fans should be running because they will switch on when the coolant reaches a specific temp and well before the coolant gets excessively hot.

4. A partial blockage in the coolant passages inside the engine but not in the radiator if you have a new one. If the coolant is not changed at the required intervals(frequently the case with many owners) or is over diluted with water you can get a build up of debris. If products like stop leak have been used in the system this can create similar problems with partial blockages inside the engine coolant passages.

5. A compression leak into the cooling system.
If you have bled air from the system and have continuous air bubbles in the cooling system I would suspect a compression leak. In that event a basic leak down test will show if you have compression gasses leaking into the cooling system and from which cylinder(s). The spark plug is removed and compressed air is forced into the cylinder via the spark plug fitting and air bubbles will show up in the coolant of there is a leak into the cooling system.
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Have the problem with overheating addressed immediately. Running the engine with an overheat condition will cause expensive engine damage many times the cost of fixing the overheating issue.

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check that you put the thermostat in the right way. The body of the unit has to be in the head / block water. Simple check is to start from cold and within 5-10 minutes idling you should start to feel hot water coming through the top radiator hose.. If in ok the bleed the air out of the cooling system by loosing off the highest hose and let the air out until you get solid water flow . Run the engine while doing this so that the water is circulated by the pump. Make sure that the heater core is open to allow the air in it to be removed

Did you also replace your thermostat? If it's stuck closed, engine will overheat.
When you did the HG, did you have head checked for cracks or warpage? A cracked head will cause severe overheating.A warped head may or may not show signs of external coolant leakage. Either of these conditions can occur if overheating is severe enough.
Are your hoses in good shape? An old hose can collapse when it's hot, and restrict flow. Feel them (when cool) for any sign of sponginess.
New radiator cap? The cap provides a seal to pressurize the cooling system.
Finally, how about your water pump? Any sign at the weep-hole of leaking coolant? Your water pump inner seal is bad, remedy is a new water pump. Or maybe the pumps' fins have corroded and not pushing coolant sufficiently. If there is corrosion, get the whole system flushed and start anew.
Pull your spark plugs and look for any sign of coolant in the cylinders. I know it's a pain to keep going back and checking, but you gotta be thorough. Plugs may be blistered white from overheating, but if you get it fixed, they should be alright.
Now, finally, really: sometimes, Randy, just a small air pocket in coolant can cause overheating. So, make sure you bleed the system if it has a bleed screw, or fill, cap loose, run engine till t-stat opens, level in radiator drops, then re-fill, and add coolant to your overflow reservoir to around the full hot mark. Tighten cap, and you are done. Good luck.

if you have no coolant leaks and all the air is out of the system then you have covered most of the things that can cause over heating.if this has a clutch fan it may not be working properly or if it has an electric fan it may not be coming on.both of these can cause a problem.it could be a water pump that has a bad impellar not circulating the coolant.the other item it could be is a bad head gasket,which you can have a combustion gas test done on the cooling system.

3.2L & 3.5L Engines

1. Before servicing the vehicle, refer to the Precautions section.
2. Drain the cooling system.
   WARNING Do not use pliers to open the plastic drain.
   
3. Remove or disconnect the following:
   NOTE It is good practice to turn the crankshaft until the No. 1 cylinder is at Top Dead Center (TDC) of its compression stroke (firing position).
   Negative battery cable Coolant recovery cap and open the thermostat bleed valve Drive belts Timing belt Water pump mounting bolts, noting the position of the longer bolt Water pump. Discard the O-ring seal.
4. Clean the gasket sealing surfaces, being careful not to scratch the aluminum surfaces.
   
   
   Fig. Water pump bolt locations, make sure to note the position of the longer bolt
   

To install:

1. Install or connect the following:
   WARNING Rotate the pump and check for freedom of movement.
   New O-ring and wet with clean coolant prior to installation. Be sure to keep the new O-ring free of any oil or grease. Water pump with a new O-ring. Torque the water pump-to-engine bolts to 105 inch lbs. (12 Nm). Timing belt Drive belts
2. Fill the cooling system by performing the following procedure:
   1. Close the radiator drain.
      
   2. Open the thermostat bleed valve. Install a 1 / 4 in. (6mm) clear hose about 48 in. (1.2m) long to the end of the bleed valve and the other end into a clean container. The intent is to keep coolant off of the drive belt(s).
   3. Slowly, refill the coolant recovery bottle until a steady stream of coolant flows out of the thermostat bleed valve. Gently squeeze the upper radiator hose until all of the air is removed from the system.
   4. Close the bleed valve and continue to fill the coolant recovery bottle to the proper level. Install the cap on the bottle and remove the hose from the bleed valve.
3. Reconnect the negative battery cable. Start the engine and allow it to reach normal operating temperatures.
4. Check the cooling system for leaks and correct coolant level.
   WARNING Be sure that the thermostat bleed valve is closed once the cooling system has been bled of any trapped air.

Good luck (remember rated this).

How hot are you talking? You checked your cooling fan? You know your water pump is good? Not loosing any anti-freeze anywhere?

Did you bleed the cooling system after refilling the radiator ? to bleed the system, fill the radiator with water and coolant. Run the engine until it is at a good temperature. Then turn off the engine and look for a bleeding screw at the oulet of the thermostat housing and turn it with a screwdriver counterclock wise. The trapped air will go out and coolant will start coming out. refill the radiator and repeat until only coolant comes out and no air.be careful not to burn yourself.

The best way to flush it would be to take off the bottom radiator hose and pump water through the fill nozzle after all the coolent is out you can then hook the hose back up and replace it with new coolant.