RB25 overheating when stopped

[s14Art]

I've noticed that the water temp on my RB25 rises when the car is idling. Once I start driving, the car cools off.

I've driven it for hours on freeways and I've never had any overheating issues. I've driven it hard with full boost (21psi) and still no issues. The ONLY time the temps go up is when I stop the car and it doesn't move. The temps just keep climbing up to the point where it starts overheating.

In other words, the car has absolutely no issues with overheating when it comes to driving, however, when I'm in traffic or the car is stopped, the temps go up.

I'm assuming this is an issue with the fans not cooling enough?

Cooling system:
New RB25 Water pump
Koyo radiator
FAL dual 12''cooling fans with shroud

[dbeiler]

Definitely sounds like a fan issue. This may be a stupid question, but when you noticed the engine is overheating, have you gotten out of the car and visually verified the fans are running? Is your fan controller kicking on the fans at a reasonable temperature?

[s14Art]

Yes sir, fans turn on around 158 fahrenheit (70 celcius). Should I set them to turn on sooner?

The reason why I make them turn on at 158 fahrenheit now is because the car used to have trouble warming up because the fans would keep it so cool. So yeah, now they're set at around 70 celcius.

And yes, I have checked that they are working when it starts overheating.

[dbeiler]

Hmm, I can't remember what my controller was set to but I'm thinking it was lower than 70C. I'll be switching to a 68C thermostat so I will definitely need to set it lower than 70C in the future.

Are you running a colder thermostat? Having your E-fans kick on early would not be responsible for your engine running cold. The thermostat should allow the engine to warm up and hold at operating temp regardless of your radiator temperature. Perhaps your thermo is stuck open? Then again, that theory is contradicted by your engine running to hot, as well.

I recommend inspecting the thermostat for leaks or malfunction. Also try a lower fan activation temp or rebleeding the coolant.

[cotbu]

Are you running a colder thermostat? Having your E-fans kick on early would not be responsible for your engine running cold. The thermostat should allow the engine to warm up and hold at operating temp regardless of your radiator temperature. Perhaps your thermo is stuck open? Then again, that theory is contradicted by your engine running to hot, as well.
That's because your theory or your understanding of how thermostats work is incorrect.

The thermostat will stay open as long as the temperature is hot enough for it to do so.
so if the temp is 220°f your t stat should be open, it's the fan and radiator that keeps the coolant at a precise temp, if the temp gets too cold the thermostat should close.

Precise, meaning an engine temp cool enough and hot enough. Aka warm!

You never said the overheating temperature, 70c isn't overheating, neither is 85c so what's was it?
If the fans kick on and temps don't drop, then you could overheat otherwise it sounds normal. But just in case.
Are your fans pusher or pullers?
Which side are the mounted on?
Coolant filled?

From a Highly Tuned Note 4.5!!!

[s14Art]

The previous owner of my car who built the motor said he didn't put a thermostat, so the car has no thermostat. That explains why it would have trouble warming up lol.

As for the fans, I'm going to set them to start running earlier and I'll see what happens.

I'll definitely keep you guys updated.

[TheRealSy90]

No thermostat can also cause overheating issues, with the coolant flowing too quickly through the radiator and not cooling off enough before going back into the engine.

Install a low temp thermostat.

[seagrasser]

Ok, so you mentioned "new water pump". If recently installed, perhaps verify that the system has the proper volume of fluid and that there are no trapped air bubbles.

If that is fine. Then there may be a partial blockage somewhere in the radiator.

[s14Art]

Issue resolved guys. Just thought I'd update.

My coolant reservoir tank was hidden somewhere underneath/beside the driver side headlamp and it had flown off the car.... THERE WAS BARELY ANY COOLANT IN THE RADIATOR lol.

Replaced reservoir and filled with coolant and it's been running perfectly fine ever since!

[future]

Lol at the fix