350Z Bleeding coolant lines

Answer to most of the common technical questions

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OMSIN
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Joined: Fri Aug 09, 2013 5:37 pm
Location: Hamilton

350Z Bleeding coolant lines

Post by OMSIN » Sat Jan 27, 2018 10:50 am

Just thought I'd share my experience changing out my thermostat this morning on the 350Z:

I can't confirm for sure, but I think my thermostat was stuffed and to be safe ordered a replacement NISMO low temp thermostat to replace (as well as new fan motors and a temp sensor just to be safe).

Using google before i started helped with getting the old thermostat off but it was a bit vague as to how everything should work after putting it back on and bleeding the air out of the coolant system. If you do a search now you'l see a bunch of americans using a funny looking funnel attach to the radiator cap and maybe a small one on top of the bleed valve, following their method without ever having done it was actually shit so ill skip to what worked for me below:


Having done whatever you've needed to do this is what i did to get the air out of my system.

Open the radiator cap
Pour your ready mix or diluted coolant into the radiator spout until it comes up to the top
Replace cap
Remove bleed valve entirely
Using a funnel, SLOWLY, pour more coolant in here until it comes to the top, wait a few seconds and it will go back down, keep SLOWLY adding coolant until it barely goes back down or you want to move onto the next step to see if you're near enough.
Replace the bleeder valve cap (careful not to over tighten as its plastic)
Turn your AC temp all the way to hot
Turn your fan speed to max
Turn your AC off as its not used to create the heat
Now turn your car on with everything screwed back on and wait for your drivers side radiator to come on (when the car is hot)
Once the fan has come on, turn the car off
Undo the bleeder valve until you start to hear a hiss, SLOWLY turn it a tad more but do not remove it completly or hot coolant and vapour will piss out everywhere
Once hissing has stopped, undo the bleeder valve slowly until it comes off or more hissing is heard.
Pour more coolant into the bleeder valve
Replace cap
Start Car again
Give the car some revs and hold it at about 2000 RPM
Feel the temp coming out of the air vents, is it hot?
if it isnt, wait for the cooling fan to come back on, turn the car off, and open the bleeder valve to let more air out
If its hot, you're nearly finished, turn the car off, undo bleeder valve, if no hissing is heard, take it all the way off and top it up with more coolant to be safe.
undo the radiator cap, check if you can put more coolant in
gently squeeze the hose underneath the radiator cap to help any air bubble come to the surface (squeezing this tube will also push air/fluid out of the bleeder valve so watch that too)
Once everything is full, including the reservoir, put the caps back on, start the car one more time and feel the air coming out of the vents, if its hot it mean that the coolant has filled all the hoses and is reaching the mechanism which provides heat for the AC system.

The end, no where else did i find instructions as in depth as that, most places just say yea do this and it should pretty much work... not helpful and not step by step