Grurgling in dash, coolant loss, no leak

OK so I'm running out of things to replace trying to figure out what's going on with my truck. 2006 Tacoma 4.0 SR5 456,000km
Things I've done:
Head gasket and water pump 2020
Radiator, rad cap, thermostat, fan clutch 2022
Value cover gaskets, plugs, and coils 2022(if relevant)
Symptoms:
Coolant loss from rad, no visual leaks, zero to minimal coolant going back into rad from reservoir, coolant smells exterior of truck, bubbling sounds in dash at start up when cold, zero to minimal heat at idle.
Engine oil is normal colour when changed. Over heating does occur due to loss of/low coolant in rad, but no clue where it's going. Rad cap is always cool to touch, even after a 4 hr drive. Upper hose hot and firm, lower hose not as hot.
I think that's it for my list. I have it going in for a pressure and compression test soon to see if that reveals anything. I am also gonna back flush my heater core this weekend to see if that is maybe the cause of the Gurgling and no heat. Please share any of your ideas that you may think is my issue, And I will keep updating this post with the results or solutions that I find.

Thanks

 

Coolant is going somewhere if its not leaking on to the ground or in the oil it must be going out the tail pipe. Test the coolant for exhaust contamination, they sell test sticks you dip in the coolant. My money is on a poorly installed or faulty head gasket. Was this a problem before the HG change?

 

Safe to say, you have a leak. Where... good question. How long (many miles) does it take to lose how much coolant? Is this a V6 w/ cool cross-over at back, between heads? That would be my first guess. Get in there with a mirror and flashlight, and see if you can't see any cherry-coloured crusties.

 

I think a compression/leak down test is a good start.
You might also do a coolant pressure leak down test also.

 

@saint277 I would say similar issues before change, but I was also getting bubbling in my Overflow reservoir that really pinpointed needing the head gasket done, but not doing that now. I believe it was 6 and 4 cylinder on the gasket(driver side, 2 closest to firewall) that was burnt out

 

@tirediron I will check in the morning how much I'm low and should be able to estimate kms since I last topped up. Yes Its a v6

 

Turns out that the heads were warped and needed 5 thousands taken off each head. Good to go now with 478k and counting!