Waterfalls after the engine cools from a good warm drive.

[radiod]

Just curious if anyone else has this or what. Basically if I go for a good hour long + drive, get the coolant temp up to 195F~200F, when the engine fully cools off I get the waterfall sounds like there's air in the system. Goes away within 5 - 10 seconds and doesn't show up again (unless I go for another nice hot drive), but I'm trying to figure out how air is getting in there. No coolant loss, no smoke out the tail pipe, no coolant in oil/oil in coolant, etc, so yeah. The overflow is filled to the top line when cold and goes about an inch above the letters when I finish the hot drive. Only thing I could think of is if it's pulling air in somehow when it's cooling off through the rad cap/overflow line, but I've checked both numerous times and they seem to be good.

Everything in the cooling system is stock.

new 190F thermostat
new stock radiator
13psi radiator cap

 

[hvyman]

Pressure test the cooling system.

What cap are you using?

 

[mirage83]

Did you have the front end of the car elevated when you filled with coolant? The heater core is notorious for holding air when you drain and refill the system. Refilling with coolant while the car is nose-high helps sometimes.

Also, did you cut the jiggle-valve off the thermostat? That can help evacuate air from the system as well.

 

[radiod]

Cooling system holds pressure fine @ 15psi. Cap is a 13psi Stant stock replacement, about 8 months old. I don't know if the nose was elevated when it was bled cause I didn't do it last, but I'll give that a shot. Haven't had any waterfalls any other time, so it would have to be pretty stuck back there. My driveway is on a hill though, so I can get the nose up pretty easy.

 

[mirage83]

Related question Hvy... any opinion on Failsafe thermostats?

 

[hvyman]

I use oem toyota and nothing else. When in doubt put it in water on the stove with a thermometer. 9/10 aftermarket stats blow balls.

radiod if you havnt had this problem and its just started happening lately id be looking for some sort of pin hole leak that only likes to leak when hot and under lots of pressure or a bhg.

 

[radiod]

Don't think it's leaking out, cause it's a pretty good rush right away and there's absolutely no loss of coolant in the overflow/radiator. I've dealt with the BHG junk before (well, cracked head, same difference), and I don't see any signs of BHG at all. It's been resurfaced and done with a cometic MHG and ARP studs run on pretty much basic upgrades, so it sure as hell better not! I'll see if burping the system does anything.

 

[Nick M]

Cap is a 13psi Stant stock replacement

They also have 16 psi cap. It will hold better for all reasons. And raise the boiling point. So instead of going to the resevoir sooner, more coolant will be in the convection system.

 

[mecevans]

I had a pinhole leak in my throttle body hose. It only leaked 1 drop of coolant but caused the same symptoms.

 

[hvyman]

Air only gets in 2 ways. A leak or a bhg. Unless the cap is bad and spits it all out but that doesnt sound like the case.

 

[radiod]

Well, after it sitting for ~4 hours after a good drive, no waterfalls. We'll see for sure in the morning but it may have just been air stuck in the heater core.