I have a 2004 350z that is having overheating problems. I first tried to bleed the system but it was very hard being the heating and ac was deleted on this car. Then I checked for leaks, no major leaks but fixed the small ones. Next I bought a new thermostat and got that installed. Then I went and bought a Megan racing radiator and threw that in. The same thing keeps happening, my car will maintain heat for about 5-10 minutes just driving then the heat spikes.

Anyone have any ideas what I can do?

 

elevate the front, and keep bleeding

 

use the Lisle funnel and search....it's a pain in the ***.

 

I’ll try both, thanks for the help

 

I elevated it, got the no spill funnel, and it’s still overheating. I sat out there and played with it until no more bubbles were coming up. There is white smoke coming from the exhaust even after it is at temp. I live in Minnesota so it’s about 15 degrees here so idk if it’s a head gasket or the cold. But again, it maintained temp for about 5-10 minutes and then just starts to overheat. I know it’s not the fans because I can watch them turn on and switch in between speeds when they need to.

What does everyone think? Head gasket?

 

It would help to have some background on your Z. How long have you owned it? What's the mileage? When did the overheating start?

 

Before you jump to conclusions, do (or have someone do) a compression test first or better, a leakdown test. That will be revealing. FWIW, it does sound like a head gasket but I’m never one to believe hunches. Test and analyze empirical data.

 

I bought the z from the fd drifter Alec Robbins, the car has 125,000 miles, he put a new vq in because the last one blew up and he said the motor has about 110,000. I bought it about 2 months ago. He said it ran just fine and I test drove it and everything checked out. I got it home and was just driving it up and down my driveway and it seemed fine then started overheating. I called him up and asked what's up and he said that it is just air in the lines so I watched multiple YouTube videos, read multiple articles, etc. to try and bleed the system because the line with the bleeder screw was deleted. I kept trying to bleed and I seemed to get the air out and after I'd drive it there would be more air in the lines. I figured it must be a leak somewhere then so I pressure test kit and found a leak in the lower hose because the clamp was worn out. I fixed that and ran the test again and found another leak in the radiator. He filled the drain hole with some sort of glue instead of buying a new drain plug so I went and bought a aluminum Megan Racing radiator figuring that I'm gonna need a nicer one if it is going to be a drift car. During this process I also got a new thermostat because they are fairly cheap and I had everything apart. From what I've seen, the fans work as they should and I can tell that when it starts to overheat that the fans all the sudden kick into the fastest setting. Everything in the engine bay is completely stock other than an intake and that he removed the ac and heater lines. I did also notice when changing the oil the other day that the oil filter is bigger than a normal filter size for a z but when I went to put the right one on I saw that the screw to hold the filter on is also bigger then normal so I have no idea what is going on down there. Even at an idle the car will maintain heat for a solid 5-10 minutes and then I can watch the temp gage rise.

 

Do both the top and bottom radiator hoses get hot?

 

Yes they do

 

Now that I went and looked again, the connection to the thermostat on the lower rad hose is hot, but the bottom of the hose where it connects to the radiator is cold still. I did already put a brand new thermostat in it. What else could it be? When I rev the engine coolant flows up very fast, and I always thought that the coolant level will go down when you rev it.

 

was it an OEM thermostat?

Try not to stress just keep bleeding and search for more tips. There are a bunch of them.

It's almost 99.99% always air in the system.

 

Yes it was OEM, and thank you.

Another concern is that all the other coolant lines are pinched off. The only coolant lines are the main radiator hoses, so I was wondering if there is supposed to be more than that for the car to cool normally? Obviously some would be for the heating and a/c that's gone but is there any other I'd need to run to bypass that?

 

So I bought a 350z and it is overheating. I have changed thermostat and radiator and still have the problem. I have been told that it is air in the system but I have bled the system multiple times and it still overheats. This car doesn’t have any of the heating or cooling lines other than the rad hoses so I’m wondering if that is the problem. The only lines with coolant running through them is the rad hoses. All the other nipples coming off the engine where coolant would be running through have been pinched off.

Anyone know if there needs to be more lines running around to help circulate the cooling system?