I have a 2003 G35 Sedan Automatic. The radiator blew while dropping my brother to school; coolant was leaking off a crack on the top. We changed out the radiator and it still overheats. The upper radiator hose to the radiator gets hot but the bottom one is cold. If you turn the heater on it doesn't blow hot air. If the cars idling it doesn't go above the middle of the temperature gauge, but as soon as you start to drive down the street the temperature starts spiking towards H.

I thought it could have been the thermostat staying closed so we changed that out (non-oem). I just fully bled it using the bleeder screw on the back of the engines heater hose and it is still having the same problems. Top radiator hose hot, bottom cold. I think we will change out the non-oem thermostat for an oem one and see what happens. Could it be a faulty water pump?

I appreciate any help, thanks!

 

You need to bleed it with a spill-free funnel... I guarantee you still have air bubbles in there. And put an OEM thermostat back in.. they're like $20 from nissan

 

Not sure bout you sedan guys, but my 05 coupe had fan problems. Got the replaced, now runs great.

It's actually an TSB, IIRC I think it extends the warranty out to 8 yrs or 120K miles.

 

Its air in the coolant lines...you need to burp the system better. As mentioned above, you will be wise to use a Lisle Spill Free Funnel. It makes quick work - but its not essential. You can do it using the bleeder valve on the rear-passenger side of the engine.

 

Holy crap!!! My car is having the same problem 2 days ago. Found coolant leak. Engine gets hot while driving, but OK when idle. No heat either. When the AC is turned on, the fans behind the radiators are not turning. This could be a bad fan motor. .I just rented a pressure tester from Autozone and will see where the leak is coming from.

Where did you buy your radiator from? Any tips for me when replacing it?

 

I had the same problem recently . after a coolant flush my car started overheating. after researching this I found that this is common in our cars. as suggested buy some members, I went ahead and purchased a lisle funnel on amazon. this thing works great for filling the radiator. but I was still hearing gurgling in the system from inside my car. because I didn't want to drain and start all over, I had to figure out a way to get the bubbles out. after trying different methods I finally got the system to burp those bubbles out. with the funnel attached and filled 1/4 or so,go ahead and raise the front of the car. that did it ladies and gentleman. I'm so glad I figured it out it was driving me insane. haha. hope this helps


edit: oh yeah almost forgot, my cap was bad as well and at night after the car cooled the upper and lower hoses would colapse and almost flatten out. apparently the cap is supposed to open and relieve built up preassure and mine wasnt doing that.

 

1 more thing I forgot to mention,have the heater all the way hot but the fan needs to be off . thats all

 

I just replaced the radiator. But still over heating. There's no leaks of any kind. Fan runs great, I also hooked up a second fan just incase. My car is still overheating. I was told by a friend to change the thermometer. Where is that located. And also does anybody know what else it could be?

 

thermostat you mean?

 

Yeah damn auto correct on my phone. I have an 03 and some shop ruined my car. It has a really rough start, it grinds pretty bad, but I just replaced the starter. And now these problems with it overheating. I need to know what to do and how to do it myself. Can anybody help?

 

Try changing your radiator cap. It might not be holding the correct pressure to keep the coolant from bleeding out into the overflow tank.

Via a friend of mine...

 

Well, I just replaced the thermostat and used the lisle funnel to get the air bubble out. Started the car with 1/3 of coolant inside funnel. Got air bubble out at idle speed. When I rev up to 2K rpm for 15 secs a couple of times, the funnel starts to fill up until I stop. No air bubbles. However, the heater is still blowing cold air (AC is off). The top radiator hose is hot, the bottom radiator hose is cold. The temp gage shows the car is operating at normal temp even when I rev it up for a, but the right radiator fan kicks in like it was running hot.

Could it be a bad water pump? I don't think the gasket is blown because there is no smoke in the tail pipe. If the bottom hose is cold, it means the thermostat is not opening up. I just installed the brand new Thermostat from nissan and installed it properly with new gasket.

Any other suggestion on this problem? Water pump change maybe?

 

Update - Fixed:

I just started the car again with the Lisle funnel and fill it up to 1/3. I let it warmed up and turned the heat all the way up (AC off). After the engine warmed up, I loosen the air relief valve (don't take it all the way out. Keep your screw driver on so you can tighten it down quickly). At this point, the coolant in the funnel starts to drop and starts to come out of the relief valve. I then tighten the relief valve. (Note - If the coolant in the funnel emptied before anything come out of the relief valve, just add more up to 1/3 of funnel.)

I Checked the cabin and hot air was blowing out of the vent. WOOHOO!!! Then I cut off the engine, let it cool and remove the funnel and dump the remain fluid from the funnel into the reservoir. Took the car for a long test drive on highway and temperature remained at normal.

I hope this helps those with similar issue.

 

See pictures. There will be three bolts attaching the thermostat housing to the engine (thermostat and housing comes as an assembly). It is a PITA to remove/install. You have to remove your intake and disconnect the two hoses at the thermostat. You don't have to drain all the coolant, but some will leak out when you remove the thermostat.

Even with the hoses and intake removed you won't be able to see the third bolt. Just go by feel. Make sure you replace the gasket between the thermostat and engine.

I suggest try burbing the air out first before changing the thermostat.

 

99% of the time the problem of heating is air in the system in this car...check the rad cap and fans first but then burp the system