It must have had a big bubble stuck somewhere in it. There's probably a burp valve somewhere in the cooling system that you can open to let the air out.

 

^ I had to get the coolant system purged at my mechanic's. He said he had to bleed the system and take out any air pockets trapped in the coolant system. That ran me $55, but it did help, cuz the radiator fans stopped working so damn hard after this purge.

 

Does anyone know if the top intake plenum has to come off for spark plug installation? I was informed that installing spark plugs on our G35's requires removing the upper part of the intake plenum... Can anyone confirm or elaborate on this please?

Spark plugs is all I have left now, rest of my work on the list is complete...

Air filter, Oil change, ATF drain/ refill, Transfer case drain/ refill, Front & Rear differential drain/ refill, PCV Valve & O-Ring replaced, Cabin air filter replaced...

Now I just need to knock those spark plugs outta the way and I'm good for some time.

 

Service manual says just the cover:

REMOVAL
1. Remove engine cover with power tool. Refer to EM-19, "INTAKE MANIFOLD COLLECTOR" .
2. Remove ignition coil. Refer to EM-43, "IGNITION COIL" .
3. Remove spark plug using spark plug wrench (commercial service
tool).

 

Nope, not needed, but you need to remove a handful of 10mm bolts to move wiring harness out of the way has well as a couple vacuum lines. I strongly suggest using a magnetized tool to remove the bolts once you've loosen them because there's not much room for your fingers to grab the bolts. The tool also makes it a lot easier to thread in a few turns upon reinstallation. The passenger side is by far the hardest, especially the towards the back of the engine. There is a DIY for the plug install.

 

Yep, trapped air. There is a bleeder valve (maybe two) you need to open when filling. When you see fluid come out of the valve, you're good to go.

When it comes to coolant replacement, a coolant condition gauge is great because it tells you if the coolant is still within it's operational spec. My coolant has 60K miles and it's still well within spec and the coolant samples show no signs of floating media.

 

See: https://g35driver.com/forums/g35-sedan-v35-2003-06/183421-diy-video-series.html

 

Thanks for the links and advice fellas... I think this will be done next week since I ordered my spark plugs from NGK.com, shipping is from Cali to NY, 3k miles.

And as for the overheating problem... it's day two now and she's been behaving so far and I think it will remain this way from now on.

 

Just curious, so I know in the future... where are these two bleeder valves located? I don't really know this car like I knew my Altima.