2012+ Coolant System/Overheating

PogiFlip

Hey guys! I've tried researching everywhere and there doesn't seem to be a thread specific to the issue I'm having.

Issue/Background: It all started this summer when I noticed my A/C would turn off by itself after some normal driving and then idling. This would happen usually on hot days here in AZ. My coolant temperature would gradually increase after 10-15 minutes idling. On really hot days (116 degrees per the car), the same coolant temp increase would happen WHILE I'm driving on the freeway going 75-85mph. All this would happen while the AC is on. With AC off, the temperatures are normal. Temperatures would usually max out one or two dots before the "H" and the AC turns off to protect the engine. From there, with the AC off, the coolant temps would decrease at a faster rate (versus the increase I've experienced) and the AC would come back on and the cycle repeats. With the idling scenario, driving after idling would decrease the temps to normal. After I turn off my car, I would hear some gurgling inside the cabin coming from the engine. This turned out to be bubbles from the coolant system which believe is a result from coolant moving from the engine back to the expansion tank.

I've attempted to use a lisle coolant funnel to burp the coolant multiple times and the same gurgling and bubbles is still present regardless of all the attempts. Maybe I'm supposed to burp from the expansion tank? I finally tried to seek help from a reputable shop here in AZ specializing in Nissan/Infiniti and the mechanic believes that the source of the air bubbles/leak was coming from this small hose on the driver side with a loose clamp so he tightened that out. The mechanic noticed that the coolant system was different from other cars he worked on and figured that around 2012 Nissan decided to go with a modified coolant system where the reservoir tank is pressurized and sealed along with the rest of the system and the reservoir tank is now an expansion tank similar to what BMW utilizes. There is an extra hose connecting from the bottom of the tank to the engine/coolant system. Also, the cap on the reservoir tank is pressurized as opposed to the radiator cap located more near the engine. I learned the hard way by trying to fill coolant from the non-pressurized cap and noticed my expansion tank was filling up to full instead!

The coolant levels are fine and stays at max when the car is cool. Coolant is OEM Nissan blue. I replaced the non-pressurized rad cap and that didn't help. Mechanic says the pressurized cap is fine, especially the car being fairly new. Coolant system is OEM except that I was told the coolant system is connected to my turbos to cool them. The heater immediately pushes good heat when turned on. The previous owner confirmed that the gurgling happened to him but the overheating never did. He told me that a lot of people ended up using the OEM radiator because it works fine without issues and AC functionality. I didn't confirm if he was referring to FI people or NA. He actually looked into installing a CSF radiator but the AC didn't work right and it leaked everywhere so he decided to stay OEM thinking AC is a must in AZ (and I agree)!

The shop I went to is leaning towards aftermarket radiator and fans, he noticed that the coolant temps stayed the same and when you turn off AC the temps shoot straight down suggesting not enough rad fan pull to cool the car. The previous owner suggested looking into the Ecutek tune but the mechanic said the tune looks ok because he noticed that the fans are kicking earlier than OEM temp thresholds and high/low fan speeds are working fine. He also said that the coolant system I have with the expansion tank should self-bleed itself since the reservoir tank is connected to the system and the bubbles should leave by itself which it did when we bled it at the shop, so no vacuum fill occurred. He didn't check the pressure in the system because he was fairly confident it was the loose clamp. Per the mechanic, the hose itself showed dried blue coolant and the leak wasn't apparent because it would drop on the heat sheild above the turbo and evaporate before hitting the floor.

So far, it doesn't seem like the resources local to me know what's happening exactly and so I've come to the forums for some assistance! I apologize for the lengthy post. I appreciate your time in reading and responding to this thread! Thank you so much!

Questions:
1. Is anybody familiar with this newer coolant system? Is the gurgling or moving of coolant from the engine to expansion tank normal for this coolant system after turning off the car?
2. When burping the coolant system, should I do it from the expansion tank instead of the other cap location closer to the engine? This was suggested by my mechanic.
3. Any help/ideas about the overheating issue?

Vehicle:
370Z 2015 Nismo
Fast Intentions Twin Turbo System
GT2860RS Turbos
2 Tial Q 50mm BOVs
FI Front Mount Intercooler
Greedy Oil Pan
Bosch 1000cc Fuel Injectors
Ecutek Flex Fuel Tune by SpecialtyZ
Walboro 485 Fuel Pump
Setrab 34 Row Oil Cooler
FI Front Tow Bar

Wilson2608

Honestly dude your boosted so If you don't have a fan mod then you probably will overheat from just sitting espcially in AZ.(using uprev or ecutek for the fan mod or just buying bigger fans) A lot of boosted people have had no problem with the stock system but then again your outside tempatures are insane. As for the coolant system being different I have no idea, hopefully someone else will be able to chime in on that. Also as for you radiator cooling your oil cooler idk how that could be true, and unless your turbos are water(coolant) cooled then that's not true either. Maybe some FI guys will be able to chime in and help you out more than I could

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Spooler

That gurgling sound is from the turbo center sections where the coolant flows through. It can do that on very hot days. It is boiling the antifreeze. Do you have the factory Hood? I would suggest this radiator. (HPI EVOLVE RADIATOR 50mm core).

PogiFlip

Thanks for the response! It could be worth looking into the tune again for sure. At least I know that others are having success with the OEM system boosted. Having the Setrab oil cooler, I understand that it shouldn't be cooled with coolant but with the rad fans so thank you for pointing that out, post edited to reflect this. For the turbos, I've been told by my mechanic that they were water-cooled after lifting and inspecting the car, he could be wrong though.

Quick update: I was able to replicate the overheating issue this morning after driving home from work (30 min commute on highway) and letting it idle for about 15-20 minutes after getting home. Turning off the AC brought the temps back down. Turning AC on brought the temps back up. The car showed 93 degrees outside on the gauge while idling. So maybe it could be more than the AZ heat?

PogiFlip

I see! Actually, I noticed this morning that the smaller gurgling is coming from the smaller lines of the coolant system so this is definitely a possibility. I do hear a couple huge gurgles at intervals right when I turn off the car though, is this still related to the turbo center sections? I'll try to post a YouTube vid up shortly of the gurgling I hear.

I have the Fujimura Carbon Fiber Hood with the two vents on the side and vents closer to the windshield.

Thank you for the rad suggestion! Will this support AC? Any suggestions for fans or does it come with it?

Spooler

Noop, I would do one thing at a time. Sitting idleing with a turbo car is just asking for overheating issues in hot climates. Your fans should kick up to high speed.

PogiFlip

I understand. On that note, here's a link to the video I uploaded to my Google Drive of the gurgling I hear. Didn't do YouTube after all since it was easier to upload it this way instead. Hopefully it's playable by now, it was for me on my laptop but not on my phone.

https://drive.google.com/open?id=0B_...VBpbnJRYk5SWUE

PogiFlip

Bump

Spooler

Yeap, that is the coolant boiling in the lines from the turbo. Normal on a hot day.

PogiFlip

Perfect! Thanks for confirming!

Zthirty4NISMO

What dilution mix are you running? I doubt there's anything restricting airflow through your coolers, but might be worth checking. I agree with Spooler that your fans duty cycle should be on a higher rate than normal with being in hot temps and boosted.

BTW..is this GeauxTigers1 old car?

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PogiFlip

I'm running the OEM Nissan blue coolant! Yeah definitely worth checking, will try later today to confirm. I'm assuming the fan cycle is related to EcuTek tune so I'll probably try to reach out with the tuner again, haven't had success yet unfortunately so I'll probably go through F.I.

After looking at the GeauxTigers1's profile and posts, yes this is his previous car. Lots of love and work was put into this car and I definitely have a lot of shoes to fill looking at all his posts and experiences with this car. Definitely fortunate and humbled with this opportunity! That's why I'm so surprised about the overheating. I guess there's another Z owner around in AZ running a similar setup with stock radiator and having no issues.

PogiFlip

Regarding the newer coolant system, I was able to finally find some information from our forums. So it looks like other people have noticed it 2012 coolant system revision. Here's the link:

2012 Coolant Overflow Bottle Has Two Caps?

In terms of assessing the status of coolant system, I used a block test kit to eliminate any gasket issues and a pressure test kit to check leaks. Essentially, the tests were negative. I've also removed the bumper to check if there's anything blocking airflow such as debris and found a little flat piece of tree/wood inside in the bottom corner of the bumper but not blocking the radiator. Used some air from a compressor tank to clean the radiator, oil cooler, and intercooler. Lower radiator hose seems hot so I don't think the thermostat is faulty but could be the radiator fan blowing hot air on it. So, it looks like the gurgling is indeed coolant boiling from the turbos.

I still need to look into the fan settings via EcuTek tune or consider upgrading to aftermarket.


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Spooler

It is normal on very hot days. I am not sure how they design factory cooling tracks for say the GTR turbos. They must do it in a way that is moves fluid through the turbo's and cooling system without the need for the water pump. I can't remember the name for it but Onan diesel generators use this for their cooling system/radiator. One way to help with running hotter is to use a larger radiator. Once you do that, if you still have issues, better airflow at slow speeds is what will need to be addressed, aka radiator fans. I have been through this same issue with my 1975 280z turbo. It can be a challenge to get it perfect when you upgrade a NA car to turbo's.

PogiFlip

The water-cooled turbo boiling/gurgling idea is very reassuring! Thank you for that. I probably would've went crazy trying to figure out the gurgling source.

Definitely noted and will focus on a radiator upgrade, fans as needed. Unfortunately, I heard the biggest challenge with aftermarket radiators is AC reliability which is definitely a requirement for AZ. You already know the previous owner attempted CSF but was unsuccessful even when installed at F.I. themselves! Of course the CSF rad was the issue. I don't know if that radiator you recommended support AC or is reliable on AC?


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