car radiator bubbling sounds!?

[bug1200]

So Im pretty much a dumbass when it comes to watercooled cars.

The radiator of my Toyota Corolla is making this bubbling sound, the rad cap flew off one time while inspecting (I didnt touch it honestly!) and I got burnt as hell and coolant reservoir is also overflowing... but the overflowing (and flying cap) stopped when I replaced the radiator cap.

any ideas on what could be causing it? head gasket?? but no white smoke in exhaust and no loss of power.
cooling system needs bleeding?

Thanks.

BTW, anybody had experiences on radiator caps just flying all of a sudden
Its a harrowing experience to look at it and it will just come to life and attack you!

[raygreenwood]

Is this a sealed, closed loop system....meaning no overflow tube?

I think you hit it on the head. There are two different types of head leaks:

1. Where the head gasket is leaking into the cylinder....and you are burning antifreeze.

2. Where you have a head gasket leak that is only on the high pressure side.....and very small where gasses are pumped into the cooling system. It can over pressurize a closed loop system and either crack the overflow tank or blow off the radiator cap.

It will usually be a leak that is on a combined gasket that is part of a water heated intake snd exhaust manifold...and may not be the head gasket.

This is also the exact symptom....of a cracked head....and that is probably what it really is. With a crack in the head in an exhaust port.....you get high exhaust pressure into the cooling system....but no coolant in the engine. Ray

[bug1200]

by overflow tube you mean the hose that connects to the coolant reservoir? if so then yes.

Its weird because my Nissan has a known bad head gasket, the coolant bubbles only when the engine is cold, but I never experienced a bubbling sound when hot and the cap is on... (edit) and never experienced a flying radiator cap!

since theres no white smoke in the exhaust that means that the cylinder gasses are leaking into the radiator, but not to the cylinder. right? sorry, Im so confused right now

[raygreenwood]

[Jon Schmid]

[KTPhil]

Yes, normally the overflow tank should not be pressurized, and has a vent and a snap-on cap with no firm seal.

The hose leading from the radiator cap's pressure relief leads to the overflow tank, and extends below the normal level of fluid in the overflow tank.

This lets excess fluid/pressure in the radiator flow freely into the overflow tank, then siphon back under vacuum as the radiator cools.

Either way, looks like you are probably "heading" for a new head gasket. But first I'd set the overflow tank/venting right.

[raygreenwood]

[jspbtown]

Am I missing something here or could this cap just have blown off because of the normal pressure inside the radiator and it was loose? After it blew off he introduced a boat load of air into the system and that's what he sees bubbling.

Have you refilled the system correctly yet?

If not then:
Start off with a cold engine.
Remove the radiator cap and inspect the fluid level.
Start the car and let it get to operating temperature.
Add coolant as the car warms up.
When you start seeing movement in the coolant have someone give the car some gas (1500-2000rpm).
If the coolant level drops keep adding fluid until it takes no more (keep the rpms up).
Once it takes no more fluid put the cap back on tightly.
Add coolant to the "hot" reading on the overflow tank.


Then drive it and watch your coolant temp and level.

[KTPhil]

I am presuming this is an older Corolla with a unsealed system. My 2005 Prius still has the "old" unpressurized system.

Maybe the OP can clarify what he has?

[Jon Schmid]

[KTPhil]

For many years Toyota (and others, probably) have been using plastic top and bottom caps on their radiators. They crack or leak at the union with the brass radiator. My '89 Corolla did this, and I had the shop put in a conventional all-brass radiator after that. I think this was a common design with the GM Metro that, like the Corolla, came out of the Fremont NUMMI plant.

The OP probably doesn't have this problem, since the leak would be obvious under pressure, but maybe would be a possible additional symptom/casualty of an overpressure situation.

[Jon Schmid]

[raygreenwood]

[KTPhil]

Yeah, the guy that fixed my Corolla said he just had a few left, and asked if I wanted him to use one of them. I said heck yes! At the time, even though new cars were going plastic, the on-the-road shops couldn't stock all those parts, so if I broke down on the road or caught a rock, I'd have to wait for parts. But they sure knew how to solder/patch brass radiator headers, so it seemed the better choice. Sheitt, I bet they can't use lead solder anymore, anyway!

Not as good as an air-cooled engine, though!

We are truly in the throwaway car era, even though they are 10X more expensive than they used to be.

[EverettB]

[raygreenwood]

[bug1200]

Sorry, I just woke up to so many replies!
i wont be able to answer all so ill just answer one

@KTPhil, its a 1995 toyota corolla with a 1.6 4A-FE engine. with less than 110,000 kilometers (barely used)

[raygreenwood]

[bug1200]

UPDATE: problem found! it is infact a bad head gasket! never thought a bad head gasket (the head is also warped) could cause the car to overheat like that!

the reason for the flying radiator cap is: 1. rad cap is broke. 2. rad cap is broke and the excess pressure in the system could not escape therefore waking up "the beast" and scalding me in the process

[KTPhil]

Good news... I think! Lots of work but you found it.

We are still curious what kind of system you have... when it's all together, please post up a picture.