Overflowing coolant

Heard a noise that sounds like water running through a pipe. Read some threads here, thought I should burp the radiator. When I took the cap off and started the engine, coolant began to overflow. What's happening here?

'05 4L Tacoma 154k

 

hmmm i would like to know as I had the same sound and planned on doing that this weekend.

 

Expands with heat.

 

Is it bubbling? If so it may be a blown head gasket.

 

It's not bubbling. Only turned it over for a couple of minutes. Should I let it run longer and see if any air comes out?

 

Did you have your frame replaced by chance? I started getting the same noise a few months after my frame was replaced. It's worse when I turn or punch the gas. Sometimes it sounds like its right behind the steering wheel, other times it sounds like its behind the radio.

Placed the truck on ramps and ran with the radiator cap off, and just like yours, coolant started coming out the filler neck. It may have helped a little, but I havent had time to mess with it again for a few weeks.

 

If there is air in the line, you should see the coolant reservoir level drop as coolant fills in where the air was.

 

The frame was replace a little over a year ago. Didn't notice the noise until the end of last winter.
Doesn't make any noise once the engine warms up, just after starting cold and accelerating. Just got back from the 600mile holiday trip and only heard the running water noise again, after start, while accelerating.

Going to take another look tomorrow, what else do I look for after letter it run longer if the noise doesn't go away?

 

Tacoma's don't have any unusual "High" spots above the radiator cap. Some BMW's & Honda's need to be "Bled" via a dedicated bolt made for this.
This is how I flush my system.
#1 Drain coolant.
#2 Fill system with water from a garden hose & leave hose running into radiator.
#3 Leave the drain or bottom hose open partway.
#4 Start vehicle and warm up till thermostat opens.
#5 When all the old coolant is flushed out shut off the engine and drain water.
#6 Siphon coolant from overflow tank.
#7 Replace drain valve and lower hose clamp. (Replacing Thermostat & temp. sender optional)
#8 Refill radiator and overflow with new coolant.
#9 Start vehicle with cap removed.
#10 As engine temp goes up to normal some "settling" of fluid level is normal as thermostat opens. (some thermostats come with a 1/8th hold drilled in them to help prevent this.)
#10 Bring up to operating temp.
#11 Replace the radiator cap when the coolant begins to overflow.

The system will self level after being allowed to cool overnight.
As long as the overflow tank hoses are airtight, coolant should be drawn back into the radiator every time it cools off.