hello everyone,I have a 2006 infiniti g35x,with 135k. I was travelling this summer and had the car sitting for about 4 months. when i came back and took it out for the first time i noticed that there was no heat at idle. The next day I also noticed the engine overheating so i assumed it was a low coolant problem and proceeded to fill up the engine coolant. The overheating stopped and i took the car into the infiniti dealership to have a system bleed done to get rid of the air pocket. I took the car home and it was ok for about 4 days. and it started giving no heat at idle again. i took it back and they re-bled it and told me that this year of g35's were really hard to bleed. again i took it home and it started it doing it again and this time i noticed the temperate going up almost to the hottest level and coming back down when i accelerate. I took the car back once again and there first guess was a blown head gasket which was my nightmare. but after they did a carbon test and checked the oil to see if it was a milky color he said he cant be sure about it being a blown head gasket. IM SO FRUSTRATED because an INFINITI dealership cant give me a proper diagnosis on an INFINITI and went on to refer me to another mechanic which i find rediculous. Im confused and dont know what step to take next. i drove the car home today and ran a few errands and the heat seems to be working ok and the engine temperature isnt fluctuating but im sure its just a matter of time before it started doing the same things again. CAN SOMEBODY PLEASE HELP ME OR GUIDE ME IN WHAT STEP TO TAKE NEXT.

 

I am having the same issue on an 04 g35x. At first, I didn't have heat at idle, I would hear a water rushing sound when I first started the car in the am. Then I noticed the car fan was running more often. Then the car started to run hot on the highway. The car seemed to be ok, on city streets. I had the system flushed and changed the thermostat. After bleeding the system I have heat again, not sure if it is just at idle or not yet. I noticed that my reserve tank is full, but doesn't seem to work. I just changed the rad cap, i hope that works. I am looking forward to what people say.

 

I'd follow this video and take a look at ~03:00.

DIY coolant service

If you follow the instructions at the end of the video you should be able to get all the air out of the system.

I'd try doing it yourself as it doesn't require too much time; just some care and attention.

 

Would air in the system explain why the radiator isn't pulling from the reserve tank, even when the coolant level is low?

 

I had the same issue as you two were having. I was getting no heat while the car was at a stop. I had my radiator bled to release any air that was inside, which, turned out to be the culprit. I never did have my G coupe (2006) get to the point where it over heated before I got the radiator bled.

 

@colorado10spro- now that you mention it, i have the exact same water rushing noise when i first start up the car and start moving. i didnt think it was a symptom of anything though.not exactly sure what to do next

 

So, I am pretty sure that I have air in my cooling system (no cabin heat at idle). I replaced the thermostat and this didnt fix the problem. The reserve tank didnt seem to be working , so I replaced the Rad Cap. I just bleed the radiator by idling the car for 15 mins with the cap off, then reving to 2000rpm and it burped out a ton of coolant. I then replaced the coolant, and did a road test around the hood. I kept the car in first or second gear and let the car rev up to 4500rpm ish. The car started to overheat. The good news is that the coolant was overflowing through the reserve, so as least that is working now. What now?

 

I also had this problem yesterday!

Car was idling...then engine started overheating.

I've been hearing the "water rushing noise" too last few weeks.

I can't get any A/C heat.

 

Are you sure the bottom or top lip of your radiator isn't leaking?

 

That is not how you burp a g35. You need to search for the proper procedure.

 

I dont. I had a pressure check done on the coolant system. Today, I elevated the front of my car and bled the radiator. I did this for about an hour, with heat, no heat, 2000rpm for 10 seconds and idle. I think this helped. I now have heat at idle and no running water sound. I am still a little worried to take it on the highway or to drive it hard. I drove it around the city for about 20 mins today and had no overheat issues, although I did hear the fan running. I never heard the fan run until the last few weeks.
What now?

 

I burped it through the bleeder valve earlier. There was still air in the system. I burped it out through the rad and bubble came out for a long time at idle. That is when I finally started to get cabin heat at idle. Do I need to bleed it out through the bleeder valve again? I am not a mechanic, so please excuse and ignorance, my degrees are in Aerospace, so rocket science I get, but this is pretty tough for one guy with few tools and little experience.

 

Is the 2" diameter upper radiator hose on the passenger side of the engine bay full or compressed? It's really not hard to "burp" our coolant system, if you did all that work (which is the correct way) and you still have cold air at idle, then you have a leak somewhere.

 

I have heat at idle now. My concern is overheating on the highway, or hard driving. I am pretty sure that the 2inch is full, but I will check in the am and get back to you.

 

Tomorrow am, I am going back to the original mechanic that flushed my coolant system. Is there anything I should tell them? Or request them to do?