Sooo about 10-15 minutes of running the engine and only about half the time, when the coolant comes back into the reservoir the coolant shoots out of the cap, & than onto the belt making a squeak sound and splattering all over the intake manifold and causing lots of smoke cause the super hot head of engine.

I'm assuming maybe the cap itself is the issue maybe its not handling the pressure or idk. maybe someone here has experienced this before or knows something about this? I'll attach a video (youtube link) to see the leak happening in action!

https://youtube.com/shorts/ewSBy1o2VAE?feature=share

Thanks Yall

 

Check the expansion tank for cracks but I would be getting a new cap. That is a VERY leaky cap.

 

That is pretty bad. Look for a crack either in the cap or the plastic reservoir

 

I just ordered an entire res with the cap so it should be here no later than the 28th, I'll check back in then.

 

That's a real bad leak and seems to be from the cap. Looks like a aftermarket URO tank whose rubber and plastic parts don't last too long to begin with. If it's been doing it awhile I would inspect your hoses real good from the collapsing they've been doing when the car is shut off.

 

So after running a brand new entire overflow tank & cap... weeks later leaked in the same spot (the cap as seen in the original video)

felt frustrated so I tried putting gasket maker & PCV tape and forcing the cap down and after multiple failed attempts

and than I went to a junkyard and got another entire overflow tank with cap (in well condition including thread & no cracks) took it home cleaned it out & installed it.
After Installing It, it was fine for about a week & a half. and than leaked from the exact same spot (the cap as seen in the original video)
note: it leaks usually after a long run & while running (slowing down) or when stopped and/or once shut off) in my opinion it leaks when the hot coolant returns to resevoir
:icon_ rain:

Only Mods: Cold Air Intake & Straight Pipe Exhaust (No Exhaust Pipe After Cats)

 

The cap in the video doesn't have a pressure rating on it. It should say 140kpa. If your new cap states that you're good. If not replace. But if it was the cap - whether incorrect, a bad seal or not tightened correctly - you would see a collapsed radiator hose in front of the engine after driving. The original problem may very well have been the cap or tank in the video but when you replaced the tank and refilled, did you burp the system? If not, you may have a airlock which would cause over pressurization leaking and possible overheating in the future.

When replacing the reservoir or flushing the system and refilling you should;

1. Refill the cooling system allowing a few minutes for air to purge the system, check for proper level and replace cap.
2. Turn car on, switch off the climate control system and start the engine.
3. Run the engine until the cooling fans operate 1500-2000 rpm.
4. Switch on the A/C system, set to maximum heat, and check that heat is coming from the heater at the vents or the footwell outlets.
5. Switch off the engine and allow it to cool down.
6. When cool, remove the pressure cap and top up the system to proper level and replace cap.

If you did all this you may have a head gasket issue. You can purchase test strips or test kit from Amazon or local your auto parts store.

 

@FreeWifi

So as far as other leaks, I've inspected all other hoses & water pump/thermostat gaskets. the only leak is 100% coming from the Coolant Resevroir Cap.

As far as bleeding or "airing out" the coolant system, yes I bleed the coolant system of air throught the bleeder valve while it warms up to operating temp. & only replace the valve once it completely stops bubbling, than Fill back up the coolant through the cap to between Minimum & Maximum.

As far as a cap that can handle the pressure.
I've bought a reman'd part, tried to forge it, & than used a brand Meyle Manufactured coolant resevoir. & obviously it went through whatever cap it went through in the beginning before replacing anything.
& I can tell you with certainty that everytime its leaked, I check & it is 100% coming from the same place: the coolant resevoir cap. also note That it doesn't ever overheat until its leaked so much coolant after maybe days or leaking that it doesn't have any in the resevoir.

If you can't think of anything else I have thought of maybe the plastic factory cap just wasnt meant to handle even hotter conditions since I am running modifications on the car and somewhat quite making it a "drift build"?

 

Bought a single reservoir cap from O'Reilly's, listed of handling only "16 lbs" or translate to 110 kpa. Its the only in store caps available. I ran it under a stress test last night:
Bled Coolant for 15 Minutes, Test ran 5 miles, Overheated, Bled for another 15 minutes, Test ran again at high rpms for 10 miles, No Issue & NO leak.

But I assume after maybe a week or two of daily driving I fear it will leak at the Coolant Reservoir Cap again.

 

Have your coolant tested for exhaust gases.