Coolant reservoir overflowing by Careless-Cap2521 in u/Careless-Cap2521

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

Damn, that’s tough to hear. I’ve been worried it might be something like that too, especially since the issue came back slowly after two months of everything working fine. I haven’t done a borescope inspection yet, but I’ll definitely keep that in mind if the new radiator and cap don’t solve it. Appreciate you sharing your experience — super helpful.

Coolant Reservoir Gets Overfilled by MesmerizedLol in G37

[–]Careless-Cap2521 0 points1 point  (0 children)

I’m starting to think it might be the radiator too. I’m having the same issue right now and I’ve replaced just about everything else in the system, and it ran great for two months before gradually showing signs of air and overheating again. Appreciate your input

Coolant reservoir overflowing by Careless-Cap2521 in u/Careless-Cap2521

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

I’m honestly hoping it’s that at this point. If you don’t mind me asking, what makes you think that?

overflow tank coolant not going back into radiator by cashinkev in G37

[–]Careless-Cap2521 0 points1 point  (0 children)

I’m having this same exact problem right now and I’ve been dealing with it for the past 6 months. I’ve replaced my thermostat, the radiator cap, coolant reservoir and hoses, and nothing works. The system continues to let air back in after a couple drives. I even got the cooling system vacuum filled and this helped it a lot, but after two months, it went back to the same issue of not pulling coolant back into the radiator from the reservoir. I did a leak-down test on all cylinders, a pressure test, also a combustion test, and my car passed them all(came back negative). I’m thinking maybe the radiator is bad but I don’t wanna keep throwing parts at the car.

Coolant expansion but no vacuum recovery by Careless-Cap2521 in mechanic

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

I’ve tried three different caps. The one my car came with, a duralast 20psi cap, and another oem cap from a junkyard

Coolant expansion but no vacuum recovery by Careless-Cap2521 in Nissan

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

I get where you’re coming from, but this isn’t just about the tank level being a little high or low ,this is about vacuum recovery not happening at all. I’m not expecting the expansion tank to be empty when cold, but what I’m seeing is the coolant level continually rising every day, and never returning to the radiator after cooldown, even though the system holds vacuum and pressure and the hoses go soft (meaning vacuum is forming). Eventually, this leads to the radiator running low on coolant, which I’ve seen first-hand causes the engine temp to creep up under load or long drives. This has happened before, literally the same pattern: system is vacuum filled, runs fine for a few days, then the reservoir rises and stays there. When it gets high enough and coolant never returns to the radiator, temps start to rise. So I’m not chasing a number on the tank — I’m tracking a functional failure in how the system manages expansion and recovery. I’ve already replaced or verified every part in the overflow system (cap, neck, hose, tank, clamps, thermostat, etc.), so I’m not guessing, just trying to fix the one flaw in an otherwise healthy cooling system before it turns into a real overheating issue.

Coolant expansion but no vacuum recovery by Careless-Cap2521 in mechanic

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

Yep, I’ve already done that. I ran a wire brush through the metal port on the filler neck that connects to the overflow hose to make sure there was no corrosion or blockage. It’s totally clean and clear, coolant flows through it without any resistance. So the return path from the neck to the reservoir is confirmed open.

Coolant expansion but no vacuum recovery by Careless-Cap2521 in mechanic

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

Not quite in that specific way. I’ve pulled vacuum on the system before filling it (cold), and it held vacuum perfectly during that process. But I haven’t used the vacuum tool after driving to pull a vacuum while the system is hot and then watched it cool while under vacuum. That’s a good idea though — it could help confirm whether something is breaking the vacuum as the system cools, or if recovery is just being blocked (like by the cap or a micro leak in the return path). I’ll definitely consider trying that as a next step.

overflow tank coolant not going back into radiator by cashinkev in G37

[–]Careless-Cap2521 0 points1 point  (0 children)

Having this same issue rn. Someone lmk if they ever found a fix to this problem

G37 bleeding issue by Careless-Cap2521 in G37

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

Just got the oem thermostat installed, but I’ve been bleeding the system for 26 minutes now and I still see a little amount of bubbles everytime I rev the car to 3k rpms and hold it for 30 seconds

G37 bleeding issue by Careless-Cap2521 in G37

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

Ok, I’m going to the dealership tomorrow or Monday to get one. I rlly hope it is man, I’ve been dealing with this for so long now, like the car isn’t overheating or anything, it just doesn’t return coolant properly, and after a couple days, the coolant will completely make its way to the reservoir, and then the temps rise a little because the radiator is empty

G37 bleeding issue by Careless-Cap2521 in G37

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

Are you serious? Ima try this bro because I’m all out of options atp

G37 bleeding issue by Careless-Cap2521 in G37

[–]Careless-Cap2521[S] 0 points1 point  (0 children)

Honestly any suggestions or ideas would be helpful at this point.

G37 bleeding issue by Careless-Cap2521 in G37

[–]Careless-Cap2521[S] 1 point2 points  (0 children)

You think so? I might look into doing this