Overheating

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240nessx
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Car: 93 240 Black Hatch

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So I've had the problem of no heat ever since i first got my 240. I tested my Rad Cap and Thermostat to both be bad and replaced them. Then after a couple weeks my car started to overheat. Come to find out my "new" Rad Cap was faulty and didnt hold any pressure. So i bought another rad cap from Nissan. After that i found out my radiator fill neck was broken and i needed a new radiator. So i replaced the radiator, bleed it out with this tool:
Image
When i went to test drive it, it still overheats. I bypassed the Heater Core for the time being just to see if those hoses were getting hot. When i pulled off to the side of the road my lower radiator hose as well as my heater hoses were ice cold. But, my upper radiator hose was burning hot.

My headgasket was also recently replaced too, about 2-3k miles ago. When i was testing my thermostat and radiator cap, i removed the thermostat and ran the car without it ever overheating.I know its almost spring and its getting warmer but does anyone have opinions or ideas of what i should try next?


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OutToWinPAHC
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If it worked without the T-Stat it tell me the pump is working you should.

Replace the T-stat again, installed facing the correct way with the bleed vent on the top. I actually prefer a 1/4 hole drilled in the top. But do this only once you verify that it is working. (put in a pt of water and heat it up and make sure it opens (should happen right before boiling)).

Then pressure test the system for 30 min at 1.3bar and make sure its holding pressure.

Fill and bleed

Check radiator cap (store can do it)
Pressure test the systems
Then bleed it.

Coolant bleeding

Jack the front of the car up front tires off the ground 4-6 inches.
Take off radiator cap
Take a 2 liter pepsi bottle cut it in half and use some black electrical tape and wrap the bottle neck a little, or get a cooling funnel
Flip it around and place the bottle neck were the radiator cap was at. Pinch off over flow line if not using the funnel.
Now start filling it with coolant about half way
Remove bleeder screw
Close bleed screw after you get a nice even stream of coolant
Squeeze the upper, and lower lined and burp out the air
Add antifreeze until you over fill the rad by a quart
Turn the heat on full blast
Start the engine and let the engine run after 3-10 minutes the thermostat will open and suck in the excess antifreeze (ambient temp affects time)
Fill it again but with about a half of quart.
Let it run until no more bubbles come out. Squeeze hosed time to time.
Replace cap, unclamp overflow hose and then shut off the engine, fill over flow 1/2 to 3/4

Coolant funnel (best to have)
Image
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240nessx
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y would i replace the thermostat again? i know its working i boiled it before i put it in and it opened. and the cap help pressure also. only thing i didnt do was pressure test the entire system yet.

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OutToWinPAHC
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Well you said the one hose is cold the other is piping hot. Even if the system has air in it, it should still open. I think your issue is a leak, but I don't like how it's not opening.

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240nessx
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alright ill try to pressure check the system one day this week, thanks

compactfean
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Are you sure its even overheating? Could be your gauge. Put a temp gun on the hot side.

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240nessx
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i used an infared thermometer, the top rad hose is at like 130degrees, the lower is at about 90 on both sides of the thermostat. its not my gauge cause it goes to the 3rd line for operating temp. then when i drove it for about 2 miles it started goin towards H so i just shut it off.

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240nessx
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I pressure checked the system and it held the pressure.

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OutToWinPAHC
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Id double check that t-stat, pressure and bleed it properly.

nofatchicks0073
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is it possible that your putting the thermostat in wrong it happens and it could have been put in upsidedown before you got it and you just put it in the same way but i would definitely say that your problem lies in the thermostat givin what you have said it cant be anything else. if its holding pressure then there arent any leaks if its staying cool without a thermostat then your pump is working sooooooooooo make sure your putting the thermostat in correctly and if thats not a problem through in a new one there isnt that much to a cooling system you just got a radiator, water pump,hoses and a thermostat sooooooooo good luck let us no what happens

compactfean
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Come to think of it are you running stock fan?how is the Clutch for the fan?

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240nessx
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I have stock clutch fan yes. it works properly, my uncle told me to hold a piece of paper in front of the bumper and see if it wants to get sucked in and it did. So im guessing the fan is working fine. As for the thermostat, the spring side goes towards the engine and the jiggler valve at 12 o'clock right?

compactfean
Posts: 2602
Joined: Thu Dec 03, 2009 10:28 am
Car: 89 240sx s13 sr gt3071r 23psi
B14 sentra ser sr20de-t 7psi
daily
Location: reno nv

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i always clock my jiggle valve at 6 oclock on all my cars. never had a problem. is there a way for you to see exactly what temp your t-stat opens? i always thought that when the t-stat is closed its best to have the jiggler valve at the bottom to make sure that its coolant flowing through it and not air....since air rises. i dont think it would make that much of a diff though. just my .02

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240nessx
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It should open at 174 per service manual. I have a 170 in and the hose going to the thermostat never. gets close to 170

Biggins240sx
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I've also had a problem with my 240 overheating. But like always it turned out to be air in the coolant system. Now being a mechanic I decided to go on ahead and buy a new tool to completely solve air in cooling systems. and it works great. Kinda costly but got it from Snap On. http://buy1.snapon.com/catalog/item_Lg. ... /49598.JPG

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240nessx
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I'm guessing its air, or a clog. But thanks ill totally look into that because I get a discount with snapon so I might as well

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240man91
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my car did the same thing to a t what yours is doing. frist off flush it if u havent it will help in the long run if not now an mine just had air in it. i have come to find out the ka cooling system is bad about holding air it takes like 20mins to get it all the way full. so try that. like this has happen to me 3thimes now lol every time i take water out to do some thing with it i have to take like 20min to get all air out. let me guss if u start it most the time it will sit there an not over heat it will idle for ever an not over heat then u drive a min down the road an it gos to red?

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240nessx
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Im going to to try to air it out with the thermostat in this weekend. Even though there is probably air in the lines, after driving to school (30 miles away with no thermostat) my heater hoses down get warm. Im guessing thats because my car never gets warm? I drive 65 all the way there so my coolant gauge is always below C. (Gauge not broken)

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OutToWinPAHC
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did you pressure test it?

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240nessx
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Yeah, the radiator neck wasnt holding pressure so i replaced the radiator. Now it holds pressure fine.

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240man91
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so dose it still over heat

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240nessx
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Car: 93 240 Black Hatch

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I dont know, I didnt get to work on it because my mom went to the hospital friday night. She somehow got lime disease. I'm gonna try to get to my car when i can, but i dont know when ill be able to.


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