I'd like to see some pics.

that's the first thing I bought when I started trying to diagnose the issue lol...works very well for getting air out of the system, but sadly the last time I tried it which was about 2 weeks ago, I got no air bubbles escaping from the system. Thanks for the suggestion though :)

Come on your at Porsche now, time to throw that funnel in the trash where it belongs. Get yourself an airlift kit or similar (I use mityvac mv4525, most complete cooking system tester I've ever used). Truly the only way to get all air out of today's engine with all their crossover passages etc etc. Japanese still seem to design systems that are easier to bleed conventionaly though.

One thought is there are two designs of the z cooling system. One uses a conventional expansion tank system and the later (I think 2012) use the tank as part of the pressurized system. If you have the later there is usually a upper return hose (I'm not at my car or looking at it currently so I'll have to verify this later and hopefully not look stupid) the return hose should have a pretty steady stream of coolant back to the reservoir. This was always a good indicator for when the plastic impeller would break on 1.8t vw engines.

Oh and ps just kidding about throwing the funnel away, keep it as the taper hole is much easier to secure the block checker in than some radiator openings, but that's really all I used it for after having a vacuum fill. Also on subject of block checkers there are different designs and the ones with two chambers are much more sensitive to very small gasket leaks (second chamber will change color)

I have the old system with the expansion tank. Also where can i get one of these two chamber block checkers that you mentioned? Would i be able to rent one from somewhere?

I doubt you can rent one. I got mine from my Matco guy but I don't think it's your headgasket.

One other symptom I'd like to add is that while either going downhill or down a flat road the car cools off fine, the moment i hit an incline the temperature starts climbing upwards all the way to 221 is the highest I've seen it go on a relatively short hill climb and this is with the ac off

While the car is moving air is helping cool the engine and coolant before it goes back into your engine.

While you're going uphill, there is more load on the engine than if you are on a flat road. So your engine is working harder to get up the hill which in turn is producing more heat. And if your coolant is that hot your fans should be on even if the A/C is off which I know you said they do.

Wish I could diag this car in person.

I ran a block test on it today and block testing fluid did not change color so as far as I can tell the head gasket is fine, while I had the coolant partially drained I decided to take a look and see if coolant was flowing as it should with the thermostat open....as far as I could tell the coolant wasn't really flowing so much as it was just collecting in the fill neck even after revving the engine up to about 2500rpm....seems like pressure just builds in the system, but coolant isn't really flowing much.

When fully warm with a non touch temp gun is heat fairly even between upper rad hose and lower and is it fairly even across the radiator? Also may test at heater core hoses too to see if flow is getting through the system. With everything flowing then temps should be fairly close to each other.

Unfortunately dont have one of those, the only thing i can tell you is just by touch both the upper and lower radiator hoses feel about the same temperature with the lower radiator hose feeling very slightly cooler. Any chance of an inrared temp reader being rented out by someone? Lol oh and as for the radiator as far as i remember the temperature feeling by hand was pretty consistent across the entire radiator

You can find IR thermometers for less than $20 on Amazon. If in a hurry, most hardware stores (eg, Home Depot) will have one for a little more. You may be able to borrow/rent one from an auto parts store.

found one at lowes after they had already closed, will have to pick it up after I get off work tomorrow and check things out, thanks for the tip though :)

what are you using to monitor your coolant temps? I dont believe you have mentioned where the indication of over-heating is coming from.

Using an obd2 scantool, more specifically one of the bluetooth scanners paired with obd fusion on my iphone. Have also used a higher end actron and they both read the same when it comes to coolant temps

what temperature do you consider to be overheating, and what temps are you reaching?

If i let it sit with the ac on idling for long enough the temps reach upwards of 240 is the highest I've let it get which is almost 3/4 of the way up the temperature gauge inside the car

will it ever reach 240 under normal conditions or is that just the highest you can get it to go worst case scenario?

If i let it keep going with the ac on and idling it will eventually hit the red zone of the temperature gauge in the car, but under normal driving conditions with and without the ac on it usually stays within the 190 to 214 range...as soon as i hit a hill though it climbs pretty quickly up to about 221 where it seems to stop...not sure if it will go higher as i dont have a really long incline to test it on and the 221 temperature was seen on a pretty short hill climb.

Without a water pump it would overheat very rapidly even while cruising at speed. I cannot imagine a VQ water pump going "weak" due to its steel impeller design. But who knows.

Sounds like an airflow issue though since it seems to act up the most at idle when there is none naturally.

Cools itself off fine without the ac on, will consistently keep the temps between 203 and 214

Ok, so took the temps at the inlet and outlet of the radiator.....both are within about 2 to 3 degrees of each other after everything has been warmed up for about half hour, inlet temp 212 and outlet temp of 210 is what the average seemed to be. Interesting to note however, when the thermostat first opened up inlet temps were around 170 and outlet temps were around 90

Ok so redid the temperature readings since i forgot to do a sweep of the radiator temps.....inlet and outlet seemed to stabilize at about 203 at both ends and doing a sweep of the radiator revealed a consistent reading of 205. One other thing, when the fans kicked on the temperature reading of the radiator dropped all the way down to 115, but no change in inlet and outlet temperatures

Hmm I'm trying to think if this is normal or not. It's been a little while since I've had an oddball cooling car but I'm thinking this doesn't sound right like the flow in the radiator is restricted but then you say the outlet is same as inlet which is good. Maybe your just picking up the cooler air blowing across the radiator. If only happening with ac on and your temps are all fairly close so flow doesn't sound like the issue I'm leaning towards a possible fan speed issue with ac on. I have not really looked at the cooling fan diagram so maybe I'll do that later but it's not uncommon to have different fan speeds and the ac should put it on most likely put it on a faster setting.

Shouldnt the outlet temperature be lower? Im no cooling system expert, but at least that's the way it works on my honda, inlet temperature high, outlet temperature low

i'd also like to take the time to note that the fan control module is a brand new unit as the previous original one that was in there died a few months back

It will be cooler but not by some outrageous number, more like 5-10 degrees from what I've normally seen. Otherwise it signifies there is restriction/blockage in the radiator causing a slow flow and spending more time cooling etc.

And just an afterthought, highly unlikely but have you checked the ECT to verify it is actually reading accurately?

Yes checked the ect, it is a brand new unit but thought I'd verify it's functionality before i installed it, it's resistance falls right in line with what the service manual specs specify at all temperatures. Also radiator is basically a brand new unit and flow tested it before installation, also passed testing but just to be sure it was clean i flushed it before installation and did a thorough cleaning of the outer surfaces.

Ok so i took some users suggestions on here when it came to the question of whether the fans were functioning correctly or not, which leads me to my next question as i havent been able to find an answer to it anywhere. Is it normal for the fans to be making an electrical type buzzing noise when they are on, i notice that when ac is off and the fan comes on it does not make this noise, but with ac on i get a constant electrical buzzing sound coming from the fans although I have heard of ac compressors making this noise also if anyone can tell which one it is. just had the ac serviced a few weeks ago when the radiator was swapped.

edit: checked ac compressor and ac line pressure. compressor wasn't location of noise and ac line pressure is within spec.

buzzing starts at about the 2:30 mark

Ok so did a direct test of the radiator fans, will have a video up shortly....

fan test...

No more input?

Can't really tell with my little phone speaker. I'll have to check later when home but not sure this is one that will be able to diag over net.

Any update on this?

yes there is...I drained the coolant system this last weekend took of the thermostat and did a back flush on the entire system, put everything back together and it seems to have helped, turned on the AC last week during a 90 degree day and it didn't overheat....coolant temps stayed around the low 190's with ac on so I guess we'll see how it goes and i'll chime in if anything else comes up :)

That is truly weird considering your input and out temps before. I really wonder if you just had an air pocket that wouldn't come out before. That's what it sounds like to me, we once had a vette that the dealer released 3 times and 3 times it overheated with the customer (embarrassing that it left without being verified 3 times and our dealer was one of the best but when the wrong people get assigned to the car then only so much can be done). Anyway it was trapped air in the upper crossover pipes. Do a vacuum fill and done no more issues, sometimes it really is the simplest thing.

Yeap, it was an air pocket. Sometimes they can be a challenge to get out.

Question: is there a way to test the high and low speed cooling fan function on our cars? If you didnt see the video already i did test them with a direct 12 volt from the battery which im assuming would run them at their high setting, but cant seem to find an answer anywhere on how to test the low speed setting.

According to page EC-486 of FSM, "Cooling fan motor receives cooling fan motor operating voltage from cooling fan control module. The revolution speed of cooling fan motor is controlled by duty cycle of the voltage." Ie, it turns the power on and off real fast. An oscilloscope would work to check output.

So what you're saying is im SOL lol