1991 240sx overheating (another overheating topic sorry)

[mywifes240]

I read a couple of threads here regarding overheating. But I did not want to hijack any threads or jump in with the same question, etc.

Here are the symptoms.It overheats after about 20 minutes of driving.I replace the coolant in the radiator itself.The reservoir tank (the white plastic container) stays full so I dont think it is flowing to the radiator.Before, I would turn the heater on to relieve the heat, but now, there is no heat coming out of the vents at all - just cold air.Also, that trick has worked and sometimes, I blast the heater and the temp needle just goes up faster.When I open the hood, there are areas that are wet with coolant around the radiator.

Before I take it somewhere for repair I just wanted to know if there is anything I can try before I get robbed by a mechanic.

Thanks in advance.

[xekushnr]

Sounds like you may have a clogged radiator. Either that or the thermostat is stuck closed. Not much you can check without getting your hands dirty.

[NISSAN240SX12]

try to remove you thermostat and see what happens. to test the thermostat boil some water in a pot and place the thermostat in the boiling water. if the thermostat opens then you know its good. if it dont replace it. do not buy a cheap thermostat. go to nissan and buy it. like xekushnr said you may have a clogged radiator or a bad thermostat. also you may have a bad radiator cap.....

[gingerbredman]

yes there is definately something blocking water flow. the only way the heater works is when your coolant passes through the heater core, so if the coolant is not moving through it, it wont blow hot air. of course, the motor has to be warmed up to blow hot..

i had this identical problem on my ka24e i bought a couple months ago. we removed the thermostat and flushed the radiator. left the thermostat out to see if the coolant was actually flowing.. it wasn't.

i removed the water pump, it must have been factory because ALL the impeller blades were gone i sh%t you not. i took mine off my ka24de and bolted it on, and bam, hasnt run hot since and heater works like it should...still need to throw a stat in though since it's getting cold

but yeah my symptoms were:-temp needle on or close to H-all the coolant from the radiator would boil over to the coolant reservoir. my reservoir overflowed, letting all the coolant out which would explain where all your coolant is going-strange noises (after running) after shutting engine off, sounds like the motor is throwing up inside, coolant was boiling -would not blow warm air inside at all

you've either got a bad thermostat, or a bad water pump i believe.

man i gotta catch some zzz's i hope this helps, good luck!

[mywifes240]

THank you all for your suggestions.I will try the thermostat test. How do I know if it is closed or open?I will search the forum for how to replace one now.

Thanks.

[vancouverbc]

THank you all for your suggestions.I will try the thermostat test. How do I know if it is closed or open?I will search the forum for how to replace one now.

Thanks.

look up thermostat in tutorial link in my signature for how to replace stat

[vancouverbc]

why did you replace coolant? were you low on coolant? you may have leak.

park your car on steep slope and run engine with rad cap off. have the interior heater on. to this a couple of times to get air out.

[gingerbredman]

submerge the thermostat in a pot of cool water. throw the pot on the stove and put the flame on. the thermostat should start to open before the water is boiling.

you'll know when it opens, just keep your eyes on the stat

.. thats how i did it. btw i found out Duralast thermostats are crap. they opened well after the water started boiling and closed rather quickly.. they may work, but i just went with a Mr.Gasket stat from AdvanceAuto

if your water pump is factory, go ahead and check for coolant flow while the thermostat is out. when you look down the radiator while the cars running, you should see it flowing like rapids down there

alrighty, i got painting to do, good luck

[mywifes240]

I replaced the coolant after each trip because the radiator was empty.But the reservoir tank was still full.There are little splashes over the engine area but I'm not sure its blowing up from.

[vancouverbc]

I replaced the coolant after each trip because the radiator was empty.But the reservoir tank was still full.There are little splashes over the engine area but I'm not sure its blowing up from.

the reservoir is full because the water is boiling over. you need to first make sure you dont have a leak. get a flashlight and inspect your entire engine. if you dont find the leak, get a pressure test at auto zone etc. look for drips on the driveway also.

this was my leak at the freeze plug close to o2 sensor



sounds like you also have air in your system because your coolant level got too low.

[mywifes240]

I tried the burping trick. It kept burping and level kept going down so I kept putting more in, then realized it was coming out underneath.Dangit! Its a leak. Thats too much for me to get into. I guess its going to the auto shop. THank you all for your help.