Coolant boils out of expansion tank

Steve C02 · Post by **Steve C02** » 09 Jun 2009, 22:29

Hi, Great forum here! Love ya guys!

Problem I'm having is that temp is normal while driving, but when I turn off the car, coolant boils out of expasion tank.

Car also never seems to build pressure in system and also, hot or cold, you can squeeze upper hose and coolant will flow in and out of expansion tank.

Any ideas gratefully accepted.

Steve

98 S70 GLT Turbo

Post by **Ozark Lee** » 09 Jun 2009, 22:39

Welcome to MVS,

For starters, what color is your expansion tank cap? If it is gray it could be as simple as replacing it with one of the newer bluish green ones. The gray caps fall apart and they were re-designed with a different plastic.

Also check the tank itself for cracks, the barb where the small hose that goes to the thermostat housing is particularly fragile and it tends to crack and leak.

Beyond that things get much more serious.

...Lee

Steve C02 · Post by **Steve C02** » 10 Jun 2009, 00:19

I replaced the tank about one year ago and it is in good shape. Put a new 'generic' cap on tank a few days ago and fluid still comes out of cap itself when I stop and turn off engine.

Car does not run hot (per temp gage) and does not smell, act hot while running, just when I stop coolant comes out of cap.

While running, squeeze the radiator hose and it feels a bit firm but not like there is pressure inside. Water pump and hoses are fairly new. No water in oil or oil in water to indicate head gasket prblems.

Again, car is not running hot in my opinion, fan works as it should, etc. Car runs great in fact. Maybe bad thermostat I was thinking but that would not keep coolant from 'backing up' and exiting the cap until temp goes down and it closes.

Thanks

Steve

Rb_newsletter · Post by **Rb_newsletter** » 09 Jul 2009, 19:48

I am facing similar problem. But I haven't changed the coolant tank. It is original tank.

When the engine is shut a stream of coolant is flowing from the front right end of the bumper and this happens occasionally. I could not find from it is leaking. But the leak is not from the tank itself. It is from some where else.

Please share any idea. Thanks.

Post by **Ozark Lee** » 09 Jul 2009, 19:57

How much coolant are you loosing? From the description of the are where it is flowing out of I would guess that you have a crack in the radiator tank. Unfortunately you can't repair the radiator once it cracks - it has plastic tanks and an aluminum core.

In relative terms a new radiator isn't that expensive and it isn't terribly tough to replace.

...Lee

Rb_newsletter · Post by **Rb_newsletter** » 13 Jul 2009, 15:22

Different amount of coolant is lost every time. Probably around 200 ml of coolant would be lost.

How much would a radiator tank cost?

Post by **Ozark Lee** » 13 Jul 2009, 17:38

You can't replace just the radiator tank, if they break you need a new radiator.

FCP sells radiators in the $200.00 to $300.00 range depending on if the car is N/A or turbo. Be sure to check the general information section on the board for the discount code if you buy one from FCP - It knocks 10% off for anything over $150.00.

...Lee

commlend · Post by **commlend** » 13 Jul 2009, 19:44

I had same problem and not sure if maybe you already tried this but, I was able to just "burp" the system. I took off the coolant cap while engine was cold and let the car idle for about 3 minutes to get any air out of system, then put the cap back on. It's worth a shot...

Post by **Ozark Lee** » 13 Jul 2009, 22:33

It's worth a shot...

Heck yes, I am a big fan of cheap and easy first. I have not had problems with air locking on my Volvos like I had on the Porsche or even my wifes old Chrysler but it is worth a shot and it costs nothing.

...Lee

Rb_newsletter · Post by **Rb_newsletter** » 02 Feb 2010, 16:01

Looks like my coolant expansion tank is cracked. I came accross the link http://www.ehow.com/how_5606749_fix-coo ... leaks.html. Is advisable to seal the crack with JB-weld? Will it cause any other problem later.