Is it the Water Pump?
 

One night after a spirited ride, Boxster dumps the coolant through the drain hose in front of rear passenger tire. Next morning get a low coolant light on the dash.. Did a pressure test after filling with distilled water.. Showed a slight leak from the water pump area on the elevated pavement, rear of the car at the highest point. Ordered water pump and parts. Added distilled water and drove it. Coolant dumps again same place. Last weekend, took front engine cover off and run the car no leaks from the pump etc... Take it for a drive with cover off, no coolant dump. Put everything back together and take it for another drive the next day. Forgot something and circled back home, coolant everywhere.. I had opened the bleeder valve the first time I added water. Now coolant bleeder valve won't go down even after sitting overnight so can't pressure test. Is this the water pump? Coolant reservoir replaced 2 years ago.. When I remove the front engine compartment, I also pulled the carpet in the rear and looked at the reservoir and saw no leaks. Coolant reservoir shows coolant on it but not sure if it's from a leak or the purge.

Should I force the valve down with a blunt object? Bad idea I'm sure... or is this the water pump? My other car had a water pump problem that didn't show signs until every other part of the cooling system was replaced. Talk about a expensive water pump job haha..

So do I need a new purge valve or is it the Water Pump? Thanks in advance..

05 Boxster 32k miles..Don't judge me:D. Reservoir replaced 10k miles ago. 04 coolant cap.http://986forum.com/forums/uploads02...1518490012.jpg

Could be the cap is not sealing. I cross threaded mine and got the same behavior.

Luckily I was able to just unscrew, add water and put back on.
I had to run with the bleed valve open for a bit to burp the lines.

Mike

What I'm thinking too.. that or the bleeder valve... condensation in the trunk...

Anymore input guys besides the cap? Please throw it out here.. I have the latest cap but could be broken after so many purges..

My purge valve is still up... what's up with that? Turned the ac on and the low speeds fan comes on.. Could it be the high speed sensors not coming on at high temps? How do you test that?

The low speed fan always turns on when the AC is on.

I had same issue this summer. The overflow is in that spot where you described. In my case the service was accomplished in Oct and the overflow occurred in Jul, I live in southern spain temperature was over 100 f that day. When I looked at the level it was above the max line, after checking it several times I came to the conclusion that it was to much fluid do to expansion and so it was over flowing the excess. Happened several times the shop couldn't find any issue, and the car always maintained normal temp when driving. To make long story longer I think I opened cap to check the level didn't get it back on correctly, saw over flow panic sets in, shop cant find a problem. Then I keep checking causing it to overflow about ever other look until someone on the list mentioned the cross threading.

The other issue could be a crack in the reservoir see if you have any fluid in the trunck under the matts.

Hey All,
Replaced my coolant cap and purge valve.. Took forum advice and had those fixed. So far, fans are running on high and no coolant splurge after each drive. On my third coolant cap.. Hope this helps the next guy... Thanks for the replies.. You guys here are great help.. Eyes on my water pump from here on out..

Splurge was in front of the right tire to correct earlier posts... Been leaking since I replaced my shifter cables. Eye on the water pump and thermostat..

Took forum advice, replaced coolant cap and bleeder valve.. All looks good so far.. Eye still on the water pump. Hope this helps the next guy.. Thanks all!