So my car overheated the other day so i checked the fluids and it was low. I topped it off and it was fine for a couple days. Yesterday it overheated and sprayed fluids out if the cap. The car has 130k miles on it so i figured the thermostat was bad ans stuck closed. I replaced that today, along with purging air out of the system.

Car was not holding tmp very well, was at 210 at idle. I took it down the raod and soon as i started the tmp climbed to 230 and topped off at 230 before spraying out of the cap again.

I noticed when burbing the system that the lower radiator hose was not gettung hot at all. After cutting the car off the hose did heat up and I soppuse that is from the fluids settling.

Only other thing I can think of is a bad water pump, it is probably stock just like the thermostat was

 

Sounds like a jammed thermostat

 

Yes it could be. I am going to cut out the oem thermostat and see what happens tomorrow. The one I got today could be defective

 

Do you get hot air out of the heater? If not there's still air in the system. How hot did the car get when it overheated the first time?

 

The air is not to hot coming out of the vents when it is full blast, if I rev the motor slightly then hot air will come out when i was working on it earlier. So i think there is stillsome air in the line. I am going to check the radiator tomorrow to see if there is ablockage. The first time it overheated it nearly peaked. I am hoping i do not have a blown head gasket, but that should not effect it having a cold lower hose. The bypass hose gets hot though. Hopfully i will learn more tomorrow

 

Are you checking the bleeder screw by the firewall?

 

A good place to start troubleshooting is in the FSM

http://www.nicoclub.com/FSM/G35/Coupe/2003/co.pdf

See page CO-06

Telcoman

 

I literally just went through thus exact problem and process on my 06 uprev. I'll try to help shorten your fix with what I learned over many days. As stated you have 1 or multiple of 3 problems: air, leak, or blockage in your system.

The shortest way to the problem while protecting for the future is this.

1. Buy a $6 Prestone flush kit and a new thermostat
2. Drain system, pull thermostat and look for signs of coolant corrosion. If there is any, wipe it out of the cavity before putting on the new one, and also understand that there may be blockages (or maybe not).
3. Backflush your coolant system with water, front passenger side jacked up, heater blowing high, in order to ensure all corrosion / conaminants out of system. If the heater core or radiator are blocked, this step will reveal it.
4. Drain system of water and refill with coolant as per normal (overflow too). Be sure your front passenger side is jacked up while burping system. Take cap off of purge connector or air bleeder when filling, and fill radiator until fluid flows out of the hole and bubbling stops, then cap. Start car, heater on high, take rpms up over 3k to force circulation through heater. Do this in 10 second intervals. After a few mins shut car off and let it cool.
5. Check radiator and overflow fluid levels, repeat steps 4 and 5 until overflow levels level off and heater doesn't go totally cold when you let it back down to idle.

Now, if you do all of this and the problem returns in a few days like mine did, then you likely have a minor air leak somewhere. I found that my radiator would leak small amounts out of the bottom when my temps went up (didn't wait until fluid was shooting out). Our radiators are known for being very cheap pieces of **** with plastic top and bottom chambers. On my G35, it appeared that either the invisible leak developed on it's own, or was the result of pressure from a stuck thermostat. Either way, that leak would suck in air and send it right to the heater core, wherein all flow would stop and the G would overheat. It would "appear" like I just hadn't burped it enough, but in fact I was sipping air in repeatedly.

If you end up needing a radiator, order it here:

http://www.sunbeltradiators.com

Turns out amazon and all my local parts stores are just reselling these for higher prices. I paid 65.00 for the same radiator my parts store wanted 200.00 for. It was on my door the next day. Problem solved for me.

Good luck!

 

Hey thanks for the reply along with everyone else. I have started what you wrote hereearlier today before i went ti work. I did a forward flush with the engine runing then a revrse flush after it had cooled down with water for about ten mins. I also tested the radiator to make sure it was not clogged itself. I can not tell if there is is an actual on the radiayor or the steam was pushing out of the upper hose at the radiator, but we are pretty sure it was not pushed out ot the cap itself.

One thing i have noticed when we worked on it the other day is the oil is not milky andit is not steaming out thentail pipes. I am going to give it another good flush tomorrow and see how things go from there.

 

Replace the radiator cap

Telcoman

 

2nd this (forgot to include it. Rad cap is another fine place for sipping air.

Sounds like you are off to a good start. So now you can fill, replace rad cap, burp, etc. The key here is to leave the front pssgr side up while doing all of this so the air bubbles can risa and exit the system properly (per nissan techs).

At the end of the burp sequence, bring the car back down to idle and see if the temp stays at the midpoint. If yes, turn off the heater and see if it still does after a few mins. If yes, turn on the a/c (load) and watch it again. If it holds your temps down solid you're done. If not, keep burping with heater, etc. It only takes me 1 or 2 cycles to get it all out.

Now, if it doesn't hold, turn the car off when the temp needle starts a climb above half (maybe at 3/4). Then go look for coolant drips. For me, I found a slight drip coming off bottom of my radiator from a hairline leak somewhere unseeable. So I was not fully pressurizing and sipping air at the same time. Look at the entire system (i.e. follow all the tubes and lines from firewall to firewall). If nothing else for piece of mind. If your system is hot and pressurized, any leaks will show themselves.

If your system is pressurizing and flowing, without leaks or blockages, then you'll have a cool motor. Don't forget that each time you go to top off the system to burp to remove the air bleeder or backflow cap and fill slowly until it runs out of one of those with no gurgling. I also squeeze all of my soft tubes a few times to push out air during the fill process.

Tell us when you have success!

 

FYI... On our RADS, that cheap plastic thing that runs the length of the top is where the steam pushes through. It ends up coming out of relief tubes that are inside the plastic twisty thing that holds the RAD in. Just twist one to the left and pull it out to see what I am talking about.

No milky is good but not the complete test of head gasket. The better test and 2nd least complicated is a simple compression test (which I did just to make sure I hadn't warped my head). After that, if still concerned, a dripdown test tells all but is the most technical.

 

Sorry for the delay, been busy with work. The original problem was the cap and the followup problems was air still in the system. I had a sealer I used since I did not have any dye and used it to find any leaks since it turns white when it dries. It would not leak when just idling, I guess not enough pressure would build up for it to do so. Under liad going down the road it finally showed itself. I will post a pic tomorrow.maybe. Its on another phone. But short the seal on the cap on the end of it degraged to the point where fluids could get out and air in. Over time it finally lost enough flyids to overheat. There is no telling how long it took. Thanks for the hlp and sorry for any grammatical errors phone keyboards suck