Hello all, I would love some help from everyone. I'm about to go insane lol. Anyways long story short, I bought a g35 for a cheap price, that being said the car needed work but i didn't think it was going to need this kinda work. Ok, so when i got the car i test drove it and ran fine then after a couple days I noticed the temperature would take a while to rise up to normal temperature. So I decide to check the thermostat and it ended up not having one. The car ran fine without a thermostat and never overheated.

I also noticed that when i would turn on the heater i would get no heat, it would barley come out warm. So i bought a oem thermostat from nissan and installed it and the car still kept overheating. I also replaced the radiator and radiator cap. I even went as far as replacing the water pump. Luckily my timing chain didn't jump out of place so everything went smooth.

I flushed out the water, it seems like the car was sitting for a while. It only had water, no coolant and the water was brownish. The water pump was really rusty but all the propellers were still there. I even flushed out the heater core. I also by passed the heater core and connected the hose directly. Now he's the weird part. I some how go the car to run without it over heating and the fans turning on. It was running like a perfectly running car. I ran it like 40 miles without a problem. And that same day i took it for a smog check and passed!

It wasn't until the next day that it started to overheat. I went for like a 10 min drive. The temperature went up a bit. A little above normal and the fans turned on and I noticed the coolant was spilling out from the over flow. The thermostat doesn't seem to be opening. Ive tried with aftermarket auto zone thermostat and the oem thermostat. The top hose by the radiator cap is hot and the one by the thermostat is cold. I don't know why they won't open.
Ive tried bleeding out the air from the cooling system like a million times and i can't get it to work it just keeps puking it out by the radiator cap. Im using a spill free funnel and thats not working.

The only thing left to replace would be the coolant temperature sensor. If that doesn't work then I'm guessing its going to be the head gaskets. But I don't see any of that "milky" substance in the oil. Also with the car on and taking off the oil cap it doesn't shoot out pressure, which is a good thing. So I'm stuck on what could be the problem. How is it possible that i got the car running good one day and then it decides to overheat the next day? I wanna know as much info as i can get before I replace the engine.

Thank you all!

 

Maybe the fan is bad

 

First relax.

I'm in the same boat as you somewhat. Bought my 03.5 G for 5k and it ran fine but I had my issues. Just got the car 2 months ago with a world of issues, but nothing major.

If you haven't had experience with our cooling systems they are a pain in the ***. Not like others you might have dealt with. You probably still have air in the system. If that lower hose is old and upper hose is hot. This is the definite sign you have a air pocket in the system.

When you drain the radiator, system of water/coolant and refill you have to refill about a gallon over a slow 2 minute period. So think I can only poor 1/4 of a gallon in over 30 seconds. But when you finish that is not all because of air still in the system.

So now you need to let the car warm up and refill. If you are full of coolant and car is still overheating I think you have air somewhere else. See how the coolant hose going up to the air relief valve is angled. Make sure you pull the plug on the air relief valve until coolant starts to come out. I ended up putting a funnel in the hole and filling up at the spot after I filled the radiator. Even a tad of air in these very sensitive systems can cause a world of issues.

Do about 4-5 intervals of adding coolant, warming the car up and letting it cool down and add more coolant. Also running it stationary with the radiator cap off will help burp the system.

I would honestly say 9 out of 10 people having cooling problems after a refill/ flush and thermostat install are from air pockets.

Do all this above before buying more parts. I hate to see people just buying stuff before they finish all the normal methods first. Get the FSM for your car. You can download for free and goes into more detail on how to refill and flush.

Come back on here after you have first made sure you have all air pockets out. If the car overheats and your lower radiator hose is hot than you have other issues but until than while your lower radiator hose stays cold you haven't fixed the air issue yet.

Hope this helps

 

Rent the following two tools to test your cooling system, before you jump to a bad engine conclusion:

Block tester from AutoZone. You take some of the coolant out from the radiator with a turkey baster, put the tester on the radiator, and suck in air while the car is running. If the color changes then you have exhaust getting into your cooling system.

Rent the coolant pressure tester. Hook it up to the radiator cap opening and pump it to about 12 PSI and if you see coolant flowing out or pressure drops than you have a leak.

You can have a bad head gasket without oil mixing in the system. You can also have oil mixing in the cooling system without a bad head gasket (oil cooler or if you have an AT the ATF can get mixed if the radiator goes bad).

The thermostat doesn't rely on anything to open other than the temperature, so stick it in a pot of boiling water to make sure they're not bad.

Since, you replaced just about everything though, I would guess a ton of air is in your system. I replaced all my components as well and it took about ~2 hours of bleeding to get it all out.

This is what I do when I bleed my system and I've done it about four or five times.

1. Fill it up
2. Leave spill free funnel
3. Rev engine to 2K just before it spills out funnel
4. Turn car off
5. Repeat steps 1-3 numerous times

Squeeze hoses in between and make sure the heat is on full blast. I also fill up the reservoir way over the max line, so it has more to suck in as the air works itself out.

After I can feel all the hoses are warm and not cold, I do the above steps a few more times. I usually still have a cold cabin at this point though, but since I know the engine is good. I take it down the freeway for a little spirited driving and cabin becomes hot as hell after it gets the last few bubbles out. I then check the overflow when the car is cooled off and top off as needed. I've done it like this several times without any problems.

 

Im trying to get the air out the system but i can't seem to get it working! I filled up the radiator with a cold engine and removed the bleeder valve to let the air out and closed it back when the water started overflowing. So then i turn on the car and let it warm up to normal temperature without giving it gas. It seems like everything was going good until the fans decided to turn on. So i decided to give the car a few hard revs and the water started rising on the spill free funnel and as soon as i stopped giving it gas the water started going in the radiator. But then it would come back up. Ive been squeezing the hose by the thermostat and it seems to suck in the water when i do that, but when it stop the water starts rising again. I forgot to mention i used to own a g35 coupe and i had the same over heating problem (kinda) but i actually got the air out of that one perfectly. Oh And by the way I tested both thermostats before i installed them and they both work perfectly fine.

I'm going to rent those tools, but it'll probably after the holidays. I hate that i can't find the problem lol i don't care if the engine is bad, but i just wanna know what the problem is

 

Have you done a full flush or did you drain and do a refill. Flush meaning run all water and warm up and drain and fill with water a few times to insure all old coolant is out and possible blockage.

The key to the problem is that lower radiator hose staying cold. It's either air or actual blockage. If you are absolutely sure you have purged the system of air I would remove all hoses and make sure one of them isn't blocked with gunk or something, especially the lower hose. Like I said before if you are overheating and the lower hose is hot I would point to other possibilities. Could be a unseen blockage, try some radiator flush crap that can loosen up the stuff if it's there. Not just the water tactic. If your coolant was brown prior to any of it, the blockage might be in the radiator. If you can't rod it out, a new radiator for our cars on RockAuto is $45. You can't beat that. Another thing to look at with the radiator is blockage, debris in between the radiator and condenser. I'm still going with the air or blockage in the system. So do what the above said and what I said and I guarantee if done right your problem will go away

 

As a last resort if you have an air compressor you can buy a tool called the Airlift. It's about 75 bucks on Amazon and I bought one a few months ago, but haven't tried it yet. Basically, it creates a vacuum on your cooling system using compressed air and then sucks in all the coolant in like 5 minutes. It should leave your system air free when complete.

I've been dying to try it out, lol. I have to maintain four cars as of now and spending hours at a time bleeding coolant out when needed is something I don't want to do. But, haven't had to do cooling work yet, but it's soon coming up.

 

Okay guys thanks for all the help, i really appreciate it. Here's an update. So now i have all the cooling hose connected where they should be. So the heater core hose are all back in place. Anyways, i found a leak by the passenger side where the top radiator hose connects to a water pipe. Its under the water pipe a small hose. How did i find it? Good question lol. I had the car on at normal temperature with the spill free funnel. With my regular garden hose i opened up the water to full blast. And forced it down on the spill free funnel and water started squirting. So i cut the hose and put it back on with a better clamp and tried releasing the air from the system again. Oh and i forgot to mention on of the heater core hose was also leaking from the firewall. I also found that out by using my garden hose lol.


After we put the hose back in we started up the car again and let it rise to normal running temperature. Started filling up the spill free funnel and just let it idle. After a few minutes i gave it a few hard revs. The water started rising up on the funnel but as soon as i released the gas the thermostat finally opened and the water started going down I turned on the heater and i finally got heat its not as hot as my g37 but its way much better than how it was before. My dad took the car for a test drive earlier and he said it didnt over heat and the heater was working fine. So as of right now it was those two leaks and possibly the heater core was the problem (its probably getting unclogged as i drive it).

Anyways thanks for the help guys. I think i finally fixed it! but I'm not keeping my hopes up lol. I'll update you guys one of these days when i take it for a longer trip. Hopefully this thread can help someone.

 

Nevermind guys false alarm I took the car for a test drive in the freeway and it was running fine but i lost the heat from the heatercore. And i decided to floor it all the way to 100mph and everything was still going fine. So i got off the freeway and the temperature started rising a bit, it didn't reach the top but it was higher than normal. When i got home i noticed that the hose that connects to the heater core on the passenger side was inflated. So water wasn't running through the heater core because I'm guessing its clogged. So I'm gonna have to replace the heater core or I'm gonna have to bypass it and ride around with no heat.