I have an 04 350z manual had a collision with a deer approximately 6 months ago, resulted in repainting both bumpers, junkyard hood, new headlight, fender, and radiator + radiator mount. All work was done by a very reputable wreck repair shop and paid for buy my insurance. As long as I'm driving around I have heat, as soon as I come to a stop (engine idling) ill have heat for about 10-30 seconds before the temp starts to drop. Motor dose NOT run hot while driving or idling. As soon as i start driving again heat comes back (also heat comes back if I slightly give it gas like holding it at 1k rpm while setting still)

 

sounds like air bubbles to me, check out this thread for some ideas

https://my350z.com/forum/2003-2009-n...abin-heat.html

 

Low radiator fluid(coolant)

 

or that

 

Took a while for me to bleed mine. It finally worked when it starting pushing out massive bubbles. It looked like it was boiling over my spill free funnel and it created quite the smoke show with coolant spewing on my engine.

 

With these cars, if you don't have a spill free kit and run it for at least 30 min you ain't bleeding all the air.

$25 on amazon. Do your self a favor.

 

I know the coolant isn't low (atleast radiator is full and reservoir is full) I guess it just isn't bled all the way... Now i don't have a no spill funnel, I'll be getting one soon! I'm the mean time should I take it back to the repair shop and try to get them to bleed it again since it was working before but isn't now? If you ask me it sounds as if they are responsible for doing so... after all the total cost of repair was over a thousands dollars the least they could have done wad properly bled it

 

I mean I would, but if they can't do it the first time. What makes you think they'll do it the second time?

 

Not every shop realizes or is willing to put the time into getting a Z bled properly. The Z is pretty much notorious for being a PITA to get completely bled because the radiator fill cap isn’t the highest point in the cooling system. Part of the problem (at least for me) is getting the Z to cycle when it’s sitting.

As others have said either purchase a no-spill funnel, fill it about 1/3 full and run the car for at least 30 mind or try the two person ‘squeeze the crap out of the upper radiator hose while the other person loosens the coolant bleed fitting’ which can be frustrating but can save you some $$.

 

That's not an efficient way to bleed the air tho. Because if any air gets in the rad cap neck you just got air into the system. And all squeezing that hose is going to do is make the air into little bubbles or pockets and probably suck air in on the rebound.

Your z ain't going to do anything until the thermostat opens up. And once it does most of that coolant is going to be throwing up out of the neck. Not through the rad. It's just worth the $25 vs several hours of endless head ache.

But if that's you're method more power to you. I just tell people buy the spill kit and be done.

 

Yep, that won’t work at all. I’m talking about using the coolant system bleed screw-valve near the firewall. You use two hands to squeeze the upper rad hose while you unscrew the valve enough to just get past the o-ring. Then close it back up before you release your double death grip on the hose. Rinse and repeat until coolant with no hint of air comes out. Sort of like bleeding the brakes. It’s not efficient at all and I’ve got one of those Lisle funnels which is awesome. Just wanted to offer an option.

 

Something I found last weekend while trying to get the air out of my system...

Get one of those funnels:


Fill it about 1/3 full, let the car run with the heat blasting for about 1/2 hour, occasionally revving it to just over 4k. After you think most of the air is out just shut it off and walk away.

I let my engine cool while the funnel was still inserted and had plenty of fluid in it. When I came back about an hour later the thing had swallowed at least another 20 oz. Not exactly sure how that worked but I have heat again.

 

The coolant expands when heated. So when you let it cool it has a vacume as it disbands, which both lowers and sucks the fluid back from the funnel.

That's what you're supposed to do. Good job and happy it fixed your issue.