over heating problem HELP!!

[TypeX4Sho]

ok i have a 90 SOHC that usually runs great but.. for the past few days it has been over heating like crazy..it all started i was on the highway the other night and the temp gauge started goin hot to i turned the heat on in my car to brng it down well it did then t started going back up again..so i pulled over and when and got a jug of water...the overflow was boiling and it had popped the top off the overflow so it was steaming like crazy..i let it cool down pop the radiator cap and almost add a gallon which is weird cause i just did a flush and fill like a week ago with no problems..so that works good for a few days...now the car constantly over heats..i figured it was the thermostat but wouldnt it really over heat at idle?? because at idle the cars great but then i start moving slow speeds it seems to over heat..now heres the weird part i went back out on the interstate with it and going through gears and such and it never over heated..what do you think it is?? it just has me stumped because if i drain it all fill it back up with new water its good for about a day and then the problem starts again?

[oz240red]

TypeX4Sho, do you have the stock fan or electric?

[-RJ-]

i would change your water pump, then when you refill it, jack your car up as high as possible and bleed the system for 30 minutes. im guessing you didnt bleed it properly, leaving air bubbles in the system, therefore causing the car to overheat.

Try that first and let me know

[Denko44]

j

TypeX4Sho, do you have the stock fan or electric?

ust wondering how would that make the car overheat.. the reason im askin is im a noob and i have a electric fan in mine and the same **** is happening with my s13

[-RJ-]

just wondering how would that make the car overheat.. the reason im askin is im a noob and i have a electric fan in mine and the same **** is happening with my s13

is there any smoke coming out of your exhaust?

[Denko44]

is there any smoke coming out of your exhaust?

nothing out of the ordinary

[oz240red]

well, the same thing happened to me... I have an electric fan instead of the stock one. The relay went bad and the fan would not turn on when the temp sensor sent the signal.

You can do the following tests:

1- turn on the car and turn on the a/c, the fan should be on.

a- if the fan does not turn on, the fan could be bad. You can try it by using cables directly plugged to the battery (ground and positive) to the positive and ground on the fan. it should spin as soon as you touch the battery with the cable (make sure you use the correct polarity)

b- If it does turn on, then take the car for a spin, then let it idle and when the temperature goes above the middle of the gauge, theh fan should kick in. if it doesnt, then you could either have a bad relay or a bad coolant temp sensor. I would start by swapping out the relay first with another one in the car, so you dont have to buy one. if that doesn't work, then you'd have to try the coolant temp sensor.

good luck

[-RJ-]

what oz said made me think, how do you have the fan wired up? the way i have mine setup is when the car starts the fan starts. you would just wire the fans to something from the ignition

[blackRB240]

I am having the EXACT same problem with a '92 DOHC. I have replaced the water pump, thermostat, and the coolant 3 times. I have narrowed the problem down to being between a blockage in a coolant passage or a bad thermostat. Today, I am trying taking the thermostat out to see what it acts like, and then putting another new one back in after if it acts okay. This really has me stumped, because the problem started when my car overheated on the highway. It turns out I had a small crack in the radiator that allowed the pressure to escape which in turn bubbled all of the coolant out. At first, I expected the head gasket to be blown, but there are no signs of a blown gasket besides the system being over-pressurized. However, while the car is running hot, the bottom radiator hose is cold, pointing to a blocked radiator or a bad thermostat, but my radiator is new. I will let you know what I find out after testing a few things.

[blackRB240]

Okay, just pulled the trermostat, runs great, no overheating, everything is just like it is supposed to be. I asked a friend whos been a mechanic for 30 years, and he said he has heard of cases where the a new thermostat might be defective for whatever reason. Change your thermostat, flush your coolant, and put new in. You should be fine.

[T240Kirk]

try looking at all your hoses make sure there is not any holes you can lose pressure and antifreeze with the slightest slit in the hoses