Overheating!! Help!!

[dragon240sx]

Well I've still got the same problem. My car is overheating at low RPM's but when I downshift and raise it above 3000 the engine will cool back off. I JUST replaced the waterpump after being told by several sources that was the issue and guess what, still overheating. Well I noticed after I started the car up and it began to overheat the hose coming out of the thermostat housing was stone cold while the top hose going into the top of the engine was boiling hot. Well I went to Nissan and told the guy this morning what was going on and he says the radiator is stopped up which is why the bottom hose is cold because the water isn't getting through...WTF? Anybody out there have any clues what's going on and is the radiator really the problem?:confused: Oh by the way, I have replaced the thermostat to so it's not that it is stuck shut...

[silnv]

If it is plugged up then try radiator flush and see if that will clean it out. I did this once and you would not believe the **** that comes out. If all else fails its an excuse to get a pretty aluminum one.

[ca18guy]

Well that sounds like it could be the problem, you replaced the water pump and the thermostat so the next logical thing would be the radiator. Its not hard to replace, a good do it yourself job.

[dragon240sx]

Latest development:

Well I flushed the radiator and also decided to take the thermostat out and run the car up the road with it out just to see if maybe it was bad and wasn't opening to let the water out of the block and the car REFUSED to overheat...I let it set for about 45 mins in the driveway after I got back and it ran perfect. This led me to believe I had a bad thermostat so I get yet another one from Nissan and install it. Guess what, as soon as the car warms up it overheats like a *****...so maybe I should just drive around with no thermostat, huh? Seriously, what's up with it not even getting hot after being on an hour w/o a thermostat but within 10 mins of running with a thermostat it's boiling...and could this still somehow be radiator related?

[ca18guy]

Are you putting the thermo in backwards? I don't know what it looks like in a 240sx to know if that possible.

[dragon240sx]

Actually I had thought that but I remembered I marked the old one with which side was facing the radiator when I took it out and I've got the new one in the same way :(

[ItzGenX]

Bleed it. This is a common problem with SR's because of people tend to just pour coolant in and think its done. Top it off, unplug injectors, open bleeder screw, then let the air out while cranking it over. Also, you can use a funnel rigged to the bleeder and have it "replace" the air with water when the air comes out. This method requires two people because one does the funnel work and one does the cranking. The first method by just cranking over the engine may take a while, but it will work. After a bunch of cranks, check the radiator and see if its topped off again -- add coolant as needed. You can also do the method by not unplugging the injectors, just idle the engine and open the bleeder screw and add water as needed. Don't run the engine too long as the system will get hot especially if you didnt sucessfully bleed all the air out the system.

[dragon240sx]

Yeah I remember hearing the coolant moving around a lot when I first added it, ran the car a little, and turned it back off. I then took the radiator cap off and added more coolant until it was full again, ran the car a little, and then topped it off one more time but I did this w/o opening the bleeder screw...so even the smallest amount of air could be keeping the thermostat from opening?

Thanks to all of you so far for your help with my problem!