I got an 04 g coupe 5at with 160k miles. Two months ago I hit something in the road and my fans started running louder and faster then I've ever heard. Did that for a week or two then I got random rises on my temp gauge while sitting with the fans running on extremely high but it never went more than 3 notches above normal at a red light. Then it randomly quit rising on the gauge stayed normal temp for a month then last night on my way home from work it almost pegged out before I pulled over and shut it off. Got out and coolant was on my passenger side electric fan like it came out of my radiator cap. I refilled it and drove home and it barely rose temp accept one time but dropped right back down. The bottom radiator hose doesn't get hot at all. And I just lost heat until I get into it a little bit and go above 40mph. Could my thermostat be stuck and cause the fans to run extremely hard and still overheat?

 

Could have a stuck thermostat, but probably have air in there also now. You need to first figure out what caused the initial issue though. I'd rent a block tester from Autozone also. It'll make sure there is no exhaust fumes in you cooling system. Check your oil as well and make sure it's not chocolate like. Then check your cooling fans to make sure they run.
​​

 

the fans run super loud and all the time so I Know they work. I just replaced the thermostat, and changed the oil, and doesn't look milky. I'm not an idiot when it comes to working on vehicles I just cannot for the life of me figure this out.

after I put new thermostat in I started it and let it warm up then it started pushing coolantout the fill hole of the radiator with the cap off before it ever even opened the thermostat, with only a gallon of antifreeze in it. I topped it off put the cap on and a minute latery fans kicked on I tried to bleed it beside the battery cover and the precious owner must've stripped the damn thing out so now I can't even get it loose to get the air out. I still have no heat and it still is over heating. Anyway I can get the little cap off that bleeder?

 

You probably still have air in the system. I never use that bleeder screw when I remove the air from my system. I use a spill free funnel, rev engine up to about 2000-2500 for a few seconds, having heat on, and squeeze the hoses for about 45 minutes to an hour. Then I usually have cold air still in the cabin, so take it for a spirited drive about 5-10 minutes and air bubbles are gone. Carry around some coolant to top off the reservoir for a few days after. I've done this procedure several times without any problems.

I'd still rent the block tester from an auto store it's like 20 bucks. You can still have head gasket or issues like that without oil mixing in. I'd also rent a coolant pressure tester as well and pump up the cooling system to see if it holds pressure.

 

if problem continues replace radiator cap sounds stupid but when you can't find ANYTHING else its that i promise.

 

I did that bleed procedure with spill free funnel. Sit there and squeezed the hose for an hour and there was no more air bubbles, took it off the Jack stands drove 100 feet and the temp gauge rose almost all the way to the top. The heat would work when I gave it throttle with the funnel on there.
I seriously don't know wtf to even do anymore Besides that block tester you mentioned but I've never used one nor do I know how haha.

 

It's pretty easy you take out some of the coolant from the radiator with like a turkey baster. Fill the tool up with the testing fluid. Then just pump the bubble on the top to suck up any exhaust fumes possibly in the system while the car is running. If it turns green/yellow means your head gasket is shot.

Coolant pressure test you hook to the system and pump it up to see if it maintains the pressure. I'd test the cap as well.

Are the hoses similar in temperature? Could be thermostat, water pump (unlikely), or clogged/dirty radiator. Do the fans turn on?

 

I just put a new thermostat in it and the bottom hose feels colder then the top hose. Before I changed the t-stat I poured water through the radiator with the bottom hose off and water came out freely where the bottom hose connects. And yes the fans only kicked on today when I put the radiator cap back on and was backing out of my driveway right before it over heated. When they did turn on the run super loud, much louder than they have ever ran.

 

If after two weeks you haven't found the problem, perhaps it time to take your vehicle to the nearest Infiniti dealer and let the pro's figure it out?

Why are you not following the troubleshooting steps in the FSM?

Just guessing is not going to resolve your problem.

Just my $.02

Telcoman

 

Have you inspected your radiator for any damage, bent fins, debris blocking air flow, etc...

You need to at least rent the coolant pressure tester and block tester. You'll be able to eliminate the head gasket as a reason for over heating and with the pressure tester you can make sure there are no leaks and check the radiator cap is within spec. Double check the thermostat by putting it in boiling water to make sure it operates correctly and it still sounds like you have air in the system if you're getting heat when you rev the RPM up.

Only other thing besides a blockage, bad radiator, or things you can check on your own is the water pump. I wouldn't recommend attempting that yourself, since you can end up skipping a tooth by messing up the engine timing. Then you'd have to take apart most of the front car to set everything back in time....ask me how I know.

I'm not one for dealers and always try to DIY, but if it's causing this much grief you might want to bring it in for professional diagnosis at least.

 

Dude still has air in the system and possibly a bad radiator cap, mark my words. OP you need to jack up the car in the front, take off the radiator cap, start the car and let it heat up with the heater on full blast, watch for bubbles to start appearing in the radiator, replace the cap and bleed air out of the bleeder screw in the back left of the engine compartment. You might have to do this a few times but eventually you'll get all of the air out, both hoses will be hot and the heater will burn your hands it'll be so hot. Very common issue in G's and can be very frustrating as you are finding out.

 

Where is the bleeder valve? Can't find it .

 

Just don't make any coolant recommendations and we're all good...............