Radiator overflow tank bubbling from radiator

I’m new to this forum and I was looking for some advice for my Tacoma. The truck currently has 265k miles on the dash going up daily. It’s running perfectly fine right now but I noticed the radiator overflow tank bubbling. Removed the radiator cap and it’ll continue to bubble for twenty minutes. Truck isn’t running hot, no water in the oil or any other symptoms of a blown head gasket. Ran a test from the radiator cap to check for exhaust gases with a blue chemical test kit. If someone can point me in the right direction and get back to me that would be amazing. I’ve only owned Toyotas my whole life and somewhat mechanically inclined to a certain point.

 

Year, engine?

 

3.4 v6 5vzfe. Replaced the radiator cap last night and haven’t been able to see a difference yet.

 

Overflow is filled to the proper height?

Are you losing any antifreeze? If so, how often do you have to add any?

 

Yes overflow tank is filled to the correct height. Yes losing coolant daily about 2 quarts a day. I drive about 20 minutes each way to work and back

 

System pressure test.

2 qt's a day is a lot of loss in 40 minutes of driving

 

Should I just pressure test the coolant system from the radiator cap?

 

And there you are............

If it's not dripping and it's not in the oil, it's going out the tailpipe.

Start pulling plugs until you find the steam cleaned one.

Does it ever miss for a few seconds on start up?

 

Cracked head more likely. Exhaust gas entering the cooling system while drawing in coolant and burning it off. If you’re losing coolant and can’t find it externally not with the oil, it’s burning through the exhaust pipe.

 

I know where the coolant is going. It’s just exiting through the overflow in the coolant expansion tank.
Trying to narrow down why it’s bubbling into the expansion tank and exiting through the overflow. Checked for head gasket issue with the blue chemical with a turkey baster looking thing.

 

Blown head gasket more than likely.

 

wait I'm a little confused here. Are you needing to top the coolant off every time you drive it, or is it returning to your overflow or what? you say you know where its going? explain.. also don't jump the gun and be so quick to assume that you have a cracked head or a head gasket just yet. If your losing that much coolant via exhaust, I think you would smell it and see it pretty clearly. I agree with a system pressure test.

 

It’s bubbling out of the expansion tank and out the overflow of the expansion tank. No water coming out the exhaust. Replaced radiator cap and system is pressurizing now. Before cap was replaced the coolant system wasnt keeping pressure when removing the cap.

 

The cap creates the pressure which in turn raises the boiling point. When a certain temp is reached, the cap releases excess into the overflow tank. If the tank is full, it just spills out. When the temp/pressure falls, the cap allows the coolant in the tank to be drawn back into the radiator.

So. If you had a bad cap, you were running hot enough to loose fluid and to not be drawn back into the radiator when cooled.

It's important to make sure the line connecting the radiator and the overflow is unobstructed and not pinched by anything, and that the overflow is intact and not cracked and leaking.

Are you saying that now with the new cap the problem has ended?

 

Make sure you burped the system. Get all the air out of there. These kick butt.

$34 Lisle 24680 Spill-Free Funnel, Standard Adapters, 11 x 7 x 7"es

https://www.amazon.com/gp/product/B00A6AS6LY/

OEM radiator cap or aftermarket? Have to be careful with those aftermarket caps. Might not be rated the same (kPa) as your original.

Attaching for reference just in case -

 

The turkey baster thing isnt 100% accurate....
If you want to use that method, lower the levels so you dont suck in coolant.
Go on a LONG drive & when you come back, immediately pull the cap & put the tester immediately on without loosing gasses....
The bubbles are most likely being formed by compression, pressurizing your cooling system due to compromised head gasket, cracked head, etc...

From experience ive had many head gasket issues on customers vehicles that would not fail the chemical test / block test...
My point is, its just another tool, not the Bible....

 

start cold with cap off......if the bubbles / burping doesnt stop.....
then your screwed.....

you're gonna lose a little coolant.....have a jug of water handy


if no bubbles at that point....before everything starts to boil.....then its not HG
or at least not that bad ....yet

then need to look at cracked head theory.....they start off only leaking when they get hot...
or its already gotten really bad / advanced


driving around loosing that much water is playing russian roulette with that head gasket....if its not that already


I would be checking the oil .....everyday, just in case

 

Pull a few plugs!

If Rusty/signs of water/coolant on them
HG or cracked head

I will never forget at a 24hrs of Lemons race……1st day….cars still running the track. our team all drinking with our 92 Lexus besides us in the pit area. Judges walked over….what are you doing?? Team member went to start our Lexus and puked coolant from reservoir. Oh Yeah…..yall are done say the judges. They continued to drink with us.

 

Replaced radiator cap and now I’m not losing coolant anymore from the overflow in expansion tank. Even when engine is hot or cold if you leave the radiator cap off it will continue to bubble non stop not vigorously just constant. Drove home from work today with no trouble on losing any coolant. What should my next step be, leak down test on the cylinders, pressure test the coolant system or rerun the blue chemical test to check for blown head gasket or crack in cylinder head

 

2rz/3rz like to eat head gaskets...

about half of sitting......are in the throws of this


Not so much on 5vz......however the heads....all the gen 1 heads have the crack problem

there's a timmy video taking same heads off a 4runner......crack ass mothers

so my idiots guess is count on replacing a head or two


Engine Head Gasket / Cracked Head Repair (Toyota 3.4L V6 5VZ-FE ) - Part 4
@ 13:00 and @ 17:50