1990 240sx Running Hot!!!

[TAmos827]

Ok I have a 90 240sx auto that seems to be running hot every once in awhile. Some days it does fine and some days the gauge climbs to H. Things I have done and things that I was told was done. Was told the Water pump and thermostat was changed, I changed the fan clutch, the two sensors on the intake manifold(Coolant temp sensor, and temp sensor) Radiator is full of fluid, Engine has Oil, no leaks that I can see from engine or radiator and no smoke from the exhaust. When it does start to run hot I can turn on the heater and I will actually cool off to normal range(since its winter the heater is good to have on. Trying to fix be for summer SC has short winters). What can be the problem... Please help. I searched and found some answers some I have already don't. Looking for a good opinion to fix the problem.

[ANVIL]

try bleeding the coolant system, there may be air in it. if that doesnt work, i would test your t-stat or just replace it

[TAmos827]

try bleeding the coolant system, there may be air in it. if that doesnt work, i would test your t-stat or just replace it

I was told it was already replaced. I have the old one in the car. But I have bought new things and there still bad I guess I will check it out.

[zach-Ka]

My friend has a dodge ram that did the same thing about a week ago and it was an air pocket. We bled the coolant and now it runs like a champ.

[S133P3R]

Was told the Water pump and thermostat was changed, ...

are you sure the parts you did not replace were installed correctly? the thermostat has a little nob on it called a "jiggle valve" that needs to be at the 12'oclock postion, when I replaced my thermostat the one I took out didnt even have one. and what temperature thermostat was put in? 170? 160? nismo (which is low but i cant remember the temp)? do you know about the quality of the water pump? try bleeding the system also, this is completely necessary after any parts of the cooling system are opened (besides the radiator cap) and very easy to do.

[TAmos827]

are you sure the parts you did not replace were installed correctly? the thermostat has a little nob on it called a "jiggle valve" that needs to be at the 12'oclock postion, when I replaced my thermostat the one I took out didnt even have one. and what temperature thermostat was put in? 170? 160? nismo (which is low but i cant remember the temp)? do you know about the quality of the water pump? try bleeding the system also, this is completely necessary after any parts of the cooling system are opened (besides the radiator cap) and very easy to do.

as far as the thermostat I am not for sure of the postion that its in or temp. and not for sure of quality. I just know that there is new permatex around the therm. housing and waterpump and the pump looks new but it could be one of those rebuilt pumps or he took it off see it was still good and just put it back on. I might need to try to bleed it and get a new thermostat and maybe a pump so I know that there new.

[S133P3R]

its maybe 100 bucks for both new, and they usually are in stock at most parts stores.... you can replace them both in a day. I removed the radiator, intake, and the better half of my wiring harness just to make access easy and it took roughly less than 6 hours (over 4 days on lunch breaks, so ur time may vary) and saved me a few hundred $$$ in labor. dont forget about bleeding either, it alone could cause the problem so try it first.... Good Luck!

[TAmos827]

its maybe 100 bucks for both new, and they usually are in stock at most parts stores.... you can replace them both in a day. I removed the radiator, intake, and the better half of my wiring harness just to make access easy and it took roughly less than 6 hours (over 4 days on lunch breaks, so ur time may vary) and saved me a few hundred $$$ in labor. dont forget about bleeding either, it alone could cause the problem so try it first.... Good Luck!

I do mechanic work its just this has got me stumped. It will only take me about an hour to change both. I also get a discount at one of the parts stores so I will get them for around 50$. I think i am going to rent the pressure tester also to double check things. I am going to try the bleeding thing though. Thanks for the help though.

Any more ideas keep them coming.

[TAmos827]

Also to add When I start it and the engine is cold it idles around 750 but after i drive it for awhile and its warm it idles around 1000 to 1300