Recall on Coolant caps

[rick3000]

The coolant level will change as it expands with the temperature, and as it is used by the car. Your coolant level will drop when you drive because the coolant is being run up the radiators, then when you park the coolant returns to the tank. (That's what the dealer told me anyway.)

Opening your tank right after driving is very dangerous. You need to let the coolant return to room temp before you open the coolant tank, and if nothing happens when the tank is at room temp. then there is probably nothing wrong.
Adding too much coolant can be bad because the tank will use the overflow above the passenger side rear wheel and leak the excess coolant out and possibly leak all of your coolant, which happened to me.

[Joji]

Cool. good to know. Any idea why the temperature light goes on when the coolant enters the radiators when the car warms up. That is why I thought maybe it needs more coolant?

[Burg Boxster]

Joji-

First off, the coolant comes rushing back up when you remove the cap b/c you are releasing the pressure in the system. When the pressure is released, you are also decreasing the boiling point of the fluid in the system. Not a good idea to do.... especially quickly. Anyhow, sounds like you definitely have air trapped in the system. You might also have an issue w/ t-stat or water pump.

You can try either the short cut bleed method or the long one. Either way, w/o proper coolant or coolant flow, you're running the risk of creating hot spots in your motor - definitely not good!

Short cut method of bleeding the system of air:
Not 100% guaranteed effective but...
Open the bleeder valve (and leave open). Drive around w/ some random accelerations, upto 5K RPM, for about 15min. Close valve and test - make sure both radiator fans are working when at operating temp.

Prescribed method of bleeding the system of air: (from Bentley)
- For tiptronic, remove fuse B1 in fuse panel to disable ATF cooler shut-off valve)
- remove filler neck trim cover
- open up bleeder valve locking clip
- fill w/ coolant to bottom edge of filler neck
- run engine at idle. Top off w/ coolant until no more can be added when engine idle is raised sharply
- replace coolant cap and tighten. Warm up engine for about 10 min at approx 2500 rpm until coolant thermostat opens. To be sure engine is fully warmed up, check to see that radiator cooling fans in front wheel wells are on.
- allow engine to run addl 5 minutes at 2500 rpm. Every 30 seconds briefly rev engine to 5000 rpm
- open reservoir cap, relieving coolant pressure w/ extreme care. Top off coolant, close cap and repeat process of intermittently revving to 5000K rpm for 5 minutes
- allow engine to idle until radiator cooling fans cycle on and off once. Shut off engine and open reservoir cap, relieving coolant pressure w/ care
- top off coolant until level reaches max
- flip down bleeder valve locking clip
-replace filler neck trim cover and cap.
- If tiptronic, replace fuse B1

The cooling system is pressurized to 19psi and has a total capacity of 18 liters (~ 4.5 gal) so don't be afraid of adding just distilled water (entire system ratio s/b 50/50 water:approved coolant).

Good luck!

[Sputter]

joji,
Go back and read your Bleeder Tab thread.

[Joji]

All right I am making some progress. I finally have the coolant level right below the max line when the car is cool. The Temperature light above 250 is off now. The new cap I ordered from Sunset works with no hissing and leaks. The only thing I notice now is when I open the trunk after a drive it sounds like the coolant is boiling. Far as I know coolant can't boil. Is it the water mixture boiling? do you think it is boiling at all.

Also if it is wouldn't the coolant tank melt since it is plastic

I also smell a slight burning smell now. not sure if it is related

thanks

[Jaxonalden]

Joji,

Quote;
Q-"Far as I know coolant can't boil." A-Yes it can, adding anti-freeze raises the boil point of water (212 degrees). The radiator cap is set at a certain pressure (8-15 psi) this pressurization of the coolant system also raises the boiling point.
Q-"Is it the water mixture boiling? do you think it is boiling at all." A- Not possible, the water and anti-freeze is a mixture. If it was the engine would be so hot that you would be getting an idiot light and the temp gauge would be well above 230 degrees.
Q-"Also if it is wouldn't the coolant tank melt since it is plastic." A-The melting point of the tank is well above the boiling point of the coolant. If the tank ever melted, you would have bigger problems on your hands than the tank.

[roadracer311]

Are your cooling fans coming on? Boiling suggests something is really wrong with your cooling system, like a stuck thermostat or cooling fans that fail to come on.