Would a coolant overflow valve dump the whole tank?

[bmx672]

Hey guys, just took a drive in 100+ deg. Got home and had a puddle under the rear. Coolant tank was empty. (I replaced the tank a few months ago and checked the carpet and connections... everything is good). I did notice some coolant by the overflow valve on the tank. Could my tank have emptied this way? All that coolant through the valve?

[boxster6354]

look at your coolant cap for part number, there is quite a few threads on here about the issue.

Search this forum for coolant cap and coolant overflow.

[bmx672]

I also replaced that a few years ago, I'm just trying to figure out where the leak came from. And if the whole volume in the tank could be pushed out with a bad cap or overflow valve. ?

[Burg Boxster]

Total coolant system holds ~5gal depending on model year and options. Tank obviously doesn't hold all that much. Sounds like you had air trapped in system and extreme heat caused a big burp. I've seen coolant evacuations from tank happen in both high heat and high attitudes. As a precaution, get it pressure tested. Otherwise, make sure you properly burp it while refilling or use a vacuum system to ensure no trapped air which could cause catastrophic hot spots...

Good luck

[bmx672]

Thanks for the advise! I think I'll go ahead and do a system flush and start from scratch with new coolant! Fisrt I'll have to research alternative coolants. I've used Porsche, but I think there are alternatives that are just as good. I'll have to search some threads.

[tommy986]

I just had a similar experience. I live in an area about 200 feet above sea level. Drove to Salt Lake City with altitudes reaching 7000 feet, also outside temps in the 100+ range. On third day driving home through Texas, noticed the expansion tank was empty. Topped off and drove another 500 miles and its still full.
Where would the discharge go normally? There is some residue in the trunk which makes me think there may still be a leak. Also found some residue under the car.

[ppbon]

Originally Posted by tommy986

I just had a similar experience. I live in an area about 200 feet above sea level. Drove to Salt Lake City with altitudes reaching 7000 feet, also outside temps in the 100+ range. On third day driving home through Texas, noticed the expansion tank was empty. Topped off and drove another 500 miles and its still full.
Where would the discharge go normally? There is some residue in the trunk which makes me think there may still be a leak. Also found some residue under the car.

... in the trunk, your coolant reservoir is most likely cracked.
Here are the replacement instructions:
Replace Coolant Reservoir

Happy Boxstering,
Pedro

[ppbon]

Originally Posted by bmx672

Thanks for the advise! I think I'll go ahead and do a system flush and start from scratch with new coolant! Fisrt I'll have to research alternative coolants. I've used Porsche, but I think there are alternatives that are just as good. I'll have to search some threads.

... instructions for the coolant system can be found here:
Install 3rd Radiator & Coolant System Bleeding Instructions
You can use any phosphate and silicate free coolant on the market, such as Prestone, etc.
They will say good for all applications.
Happy Boxstering,
Pedro

[tommy986]

I have a new coolant reservoir ready to install. It looks like the spot for the dipstick tube is covered. Do I just drill that out? What size drill bit?

[tonycarreon]

Originally Posted by tommy986

I have a new coolant reservoir ready to install. It looks like the spot for the dipstick tube is covered. Do I just drill that out? What size drill bit?

haha. i had the exact same question. yes, you have to drill it out if you want to keep using the dipstick. i just measured the bit at home depot with a spare quarter. some people also just use an exact-o knife. the part you cut is quite thin.

[Paul]

I use a Dremel.