I have a procharged 04 350z that has been intermittently overheating. I have done all the tests you can with the entire cooling system and nothing shows sign of being completely broken.
I have no heat at idle, a great amount of coolant gets sent back into my overflow. I can wait for car to cool, open radiator and put all the coolant back in and the car will be good for about a day.
I've started to replace things, about 2 weeks ago I replaced the thermostat, bled the system and everything was working perfectly, heat at idle, great temps not one single issue.
Here I am 2 weeks later and my heat stopped working at idle, I check my overflow and it is halfway full and 5 mins later the car starts to overheat.
I am at a loss, pressure test was perfect, no signs of head gasket, no leaks.
I have just ordered a new thermostat and decided to throw a new radiator in while i have it all apart.
It has to be something with the thermostat right? Considering after I replaced it, it was working perfectly for 2 weeks, now same exact issue is occurring. I am lost

 

Elevate front end, bleed more

 

Would it really take 2 weeks for it to show that there is air in the system? But yes I will keep bleeding it.

 

Yes, especially if you are not bleeding it properly to begin with. Are you elevating the front, using a lisle radiator funnel, properly opening the bleed port, and bleeding with the car running and heater on? If you say no to any one of these then thats most likely the problem. If your are doing all that then I would guess radiator, but an air bubble sounds more likely.

 

Yes i have been doing all of that, the shop even bleed it for like 2 hours and it happened an hour later, it's been fine for the last few days with me driving it a little hard sometimes to test, new radiator just got here last night so whenever i put it in sometimes in the next week will see how that goes.

 

Make sure 100% positive both cooling fans are working. If only one is working it will boiling over in stop and go traffic and at fast food drive thru.
If not start bleeding. Does it run hot while driving without stopping or all the time?

 

Both fans work. Stop and go and continuous driving like highway both will overheat. It seems as when i'm on the highway it is fine, but if i get off, turn the car off for like half an hour, then it'll overheat once i try to leave again.

 

sounds like you need to take it to someone who knows what they are doing

 

Air in system. You need to make sure you do not have a head gasket issue.
I'm not familiar with that pro charger kit but does it have a air to air intercooler in front of the radiator.

 

I did when it first started, bled the system, ran a bunch of tests and it was fine. Later started up again. I plan to go back once both I and the shop cn make time to have the car in.

 

There are no signs of head gasket, done oil change and always check the cap for milky stuff, nothing, no white smoke, no mix in coolant, no loss of performance. Yes there is an intercooler in front of the radiator, just installed a bigger radiator about a week and a half ago. No luck with that.

 

Not saying the intercooler is the problem. But in the world of drag racing and street cars which I'm from Grand Nationals and Mustsngs are famous for installing front mount intercooler and temps rise if not driving above 30 mph. An intercooler and the AC condenser along with a small opening on the front of a 350 Z I could see it restricting airflow. Did it run hot before the procharger? I still think it has air in the system.
I agree with others get the front end on jack stands or ramps and starting bleeding. If the heat stops working at any point that is a sign of air in the system. Get a temp gun and check the hoses to make sure the engine is really hot. It could be air by the temp sensor showing it is hot when the rest of the engine is normal temp. Good luck.

 

Thanks, and I could see it being a problem, but so many other z's do it without issue. The car never ran how before but we had swapped a different engine in right as we put the procharger on. There is def air in there when it does overheat, i keep bleeding so it has to be getting in there somehow.

 

Have you checked the bleed line from the reservoir to the radiator? if there is a crack or split in that it would explain air getting in.

 

Ever find the problem?

 

Not yet!

 

All hoses and lines seem to be good, help pressure just fine.

 

Hate to be the one to suggest it, but it sounds like it may be a small headgasket leak between the cylinder and the jacket.

 

Yes on possibly the head gasket. Did you run that test you can get from Amazon to see if there is carbon dioxide in the radiator fluid?



This last time, it took me three tries to get the radiator completely clear of air bubbles. Random over heating in fast food lines. I did though, eventually discover the REAL reason it was a problem for me this time around. There was a tiny leak in one of my radiator hoses and over time I was loosing fluid and of course air was being introduced into the system. The way I found it is was to use this:

So, you pressurize the radiator cooling system, grab a light and take the shroud off the bottom and start looking for fluid. Actually, by the time I jacked the car up, put in some more fluid and took off the bottom shroud I easily spotted it. Here it is, the yellow hose that was clear of the A/C flywheel, but was flexing under load and slowly a pin hole was created. I had used this hose for 9 months before it failed, so never even considered that my problem would be a leak. I went back to a Rigid black OEM hose to solve it permanently.





Like everyone else has already stated Jack the front up super high, put this funnel on and run it up and down with the heater on at all times. I set the timer on my phone and go a minimum of 30 minutes. A fair amount at 3k rpm as it says in the manual.

 

Sounds like you have done everything that I wrote in the above list. Test for Carbon Dioxide in the Fluid which is coming from the combustion chamber.