You smell coolant because you have a coolant leak. Rent a pressure tester, buy a telescoping inspection mirror and a good flashlight and pressure test the system (it's incredibly easy look up a youtube video).

Doesn't sound like a thermostat issue at all.

 

Always test the cap first, it should automatically start blowing off extra pressure past the rated limit on the cap but should hold pressure below it's rating and not continue to leak. If the cap is leaking then reapply the tester 4-5 times to verify it's not just the indent in the gasket (where it was attached to the radiator fill neck) causing the problems.

Then test the radiator, max test spec for the 2003-2006 G35 is 23psi, DO NOT EXCEED THIS PRESSURE. Typically I only test at at 18psi which is the generic mark the Stant tester recommends for a 15-16 psi cap. If I absolutely cannot find a leak even though I'm sure there is one THEN I'll ramp up the pressure to 23psi.

There are quite a few different points on the engine where it can leak coolant from and some of them are really hard to inspect without a telescoping inspection mirror, YOU WILL NEED ONE so don't disregard this inexpensive tool for your troubleshooting.

 

Thank you Cleric for your help.
Looks like I may not have to do as much testing as I thought....

Went out this morning to take a closer look and discovered this:

1. Coolant sprayed across the front right area near the radiator cap
2. Coolant sprayed on some the hoses
3. No coolant in the reservoir tank
4. Unrelated (slight oil leaking from the valve covers?)
In your honest opinion, does this look like:

A. A bad radiator cap
B. Bad radiator hoses
C. Both?

Should I continue with the test you mentioned earlier at this point?

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Yes absolutely pressure test, should be easy to find the problem. Most parts houses just require a cash deposit to "rent" the tester, you get your money back when you return it and there's no actual COST.

 

Thanks for your assistance with this one Cleric.
That's the route I will take and should know more in the next few days

 

Just a quick update guys....had the system pressure tested a few weeks ago.
Turns out the radiator had a crack at the top near the neck.

Replaced it today and all is well!
Car and cooling system drive phenomenally

Hell even the fan clutch stopped roaring and my coolant temps stayed between 181* and 186* with an avg of 183.6* while driving all around town. Much better vs the 194*-204* I normally see (was 58* outside today)

Thanks Cleric for all your help.
You definitely know your stuff

 

Awesome, glad you got it all fixed.

 

Anytime Cleric!
Your help was Paramount to getting the car in order

 

All right did was point you in a direction that might work, YOU fixed your car.