Help 1997 240sx OVERHEATING!!!!!!!!!!!

[RT-590ZSX]

Ok here's the deal. I've search the site and found useful info about overheating and tried a few recommended things but I can't get to the root cause. I will try to break it down and give good details so there wont' be any misunderstanding.

1997 240sx94,000 milesAuto transmission

Problem:-Car overheats and coolant boils over in the reservoir tank.

-If siting and idle it takes a really long time to get to the H but it still overheats.

-If siting but rev the engine the about 3000 rpm for 4 minutes it will get to the H and overheats.

-Starting cold if I take it out for a drive it overheats in about two mins and coolant boils out of the reservoir tank.

Things I've done:

-Change radiator cap.

-Change Thermostat

-Flush coolant (car on inclined to reduce air bubbles)

Things I've notice:-Water pump seems to be ok( this might be stupid but I left the radiator cap off and then rev my engine and coolant gushed out so I'm guessing the water pump work. If it didn't it wouldn't do that right?)

-Top radiator hose is hot

-Bottom radiator hose is cool

-No milk or oily substance in coolant

-I have heater on full blast and it doesn't feel that hot eventhough car is near the H on the temp gauge possible air bubble in heater core. I think this was cause by following the FSM for flushing coolant with the "removing heater hose from petcock prior to filling'.

Do you guys have any suggestions? Could it be air bubble? I heard of burping the system but what is the best way to do that?

I've also heard but never tried boiling your thermostat and then wedging asprin in it to keep it open then fill coolant with engine running to reduce air bubbles.

Please help. There's too much information and short of tearing the whole engine and cooling system apart I'm at a lost on how to fix this.

[ddgsxr504]

Yeah it sounds like you have air in your system.

I've tried to remove the little breather screw located on the intake manifold (where the top hose meets the intake manifold) but it never works for me.

I just top off the coolant and then drive for a few minutes. When it starts to overheat I pull over and pop the hood.

I use a heavy duty rag and gloves to break the seal and let the pressure come out of the radiator cap. If you apply pressure to it as you unscrew it slightly you will be fine, once the pressure evacuates I remove the cap to find nothing in the radiator.

I then top the radiator off and repeat the process about 2-3 more times.

My coolant temp always sits slightly below the halfway mark.