marksae

Yesterday at the track, I had coolant coming out of the reservoir during every session. It made a mess in my engine bay.


During the track day, the engine performed like normal. Temperature gauge read normal. Power felt normal. There was no white smoke coming out of my tailpipes.

I've done several track days prior to this and never had a problem. My car does now have 118k miles on the stock cooling system. It was also super hot at the track yesterday (107°F). My car never experienced any prior cooling issues until yesterday. It had no problems driving home (155 miles) with the AC on full blast the whole way.

Anyone else experience this problem at the track? I'd like to know how you fixed the issue. I'd hate to go another track day and have to deal with this problem again.

I'm thinking the cause would be one of several things.

1) Bad radiator cap - An old cap may have a weakening spring which lets too coolant flow into the reservoir, overfilling it
2) Blown headgasket - cylinder pressure is entering the cooling system, over-pressurizing the system and overfilling the reservoir.
3) Bad reservoir cap - leaky cap not doing its job containing coolant in the reservoir

Below is some other relevant information:
July 2013 - 68k: Replaced coolant reservoir cap (OEM parts).
May 2015 - 97k: Changed and bled the coolant per the procedure in the FSM. One container of Honda coolant used and filled the rest of the system with distilled water
Dec 2016 - 114k: Track day with no issues

SiLvErMyS2000

my radiator cap was bad and cause coolant to go into the overflow and if i popped the hood the overflow would be bubbling and shit went everywhere if that helps. Btw its cheap so might as well try it

gptoyz

So most likely the water temp increased compared to your normal operation, and the radiator cap which is a pressure release valve, popped to let boiling hot coolant/water to go into the reservoir.

Prior to the track day did you leave coolant in your reservoir/overflow?

Couple of things:
1) that's too much of a coolant mixture. I use less than 25% concentrate and the rest is DI water and water wetter. Water has better heat capacity than coolant which is really anti freeze which is to protect against freezing
2) a higher bar radiator cap will require higher pressures before the coolant/water boil over
3) as you drive in hotter and hotter temps the water in the water/coolant escape via evaporation leaving you with more coolant concentration which will reduce your cooling capacity.

har-vey

You must have cracked the overflow bottle as it should be sealed

marksae

Is it a good idea to run a higher pressure radiator cap on the stock radiator? My concern would be putting extra load on the plastic end tanks on my aged radiator.

I'll also run more of a water mixture going forward.

jyeung528

replace your radiator cap.

//steve\\

A new higher performing radiator isn't that expensive. At your mileage I'd just put a new radiator in.

devildust

I just stared having same issues last two track days. Temp guage stays normal but coolant blowing out through overflow. I just rebled the system and found lots of air, I'm hoping this will fix my issue, cavitation was possible. My coolant mixture might also be a little too high, I'll try to water down.

dwb993

Good suggestions here. Also check to make sure you haven't cracked the plastic internals of the radiator. Grab the upper hose and squeeze. Look for coolant coming out onto the foam strip on the front of the radiator.

I had to replace my OEM with a Koyorad unit---make sure you replace the cap, as well.

99SH

Negative. You need to vent to atmosphere downstream of the overflow fitting

Similar thing happened to be and it was a bad seal under the radiator cap..