Coolant Leak - 986 Forum - The Community for Porsche Boxster & Cayman Owners

I've noticed recently that I've got a slight coolant leak. It's not much but the level drops slightly every few hundred miles. I tried to find some sign of the leak (carpet in the boot is dry etc) but found nothing until this weekend when I finally found a trace of the leak. It seems to be dripping onto the chassis support by the right rear wheel around the point of the fourth bolt I've circled in the picture. You can see where the coolant has stripped the paint off the metal on the support on that side of the car. I can't see where the leak is coming from though, I can only work out it seems to be seeping onto the top of the chassis support at that point circled. Any idea where the leak could be from? To give you an idea of position that fourth bolt circled is roughly in line with the centre of the rear wheel. Thanks

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... just by feeling the carpet in the rear trunk. You actually need to lift it out to see if there's any coolant in the trunk.The liner has spacers that sometimes make it appear dry when in reality there's a coolant puddle underneath. If after you lift the bottom liner in the trunk it is dry then the leak could be coming from a bad coolant cap or a bad bleeder valve and going through the overflow hose. The last version of the coolant cap ends in 04. If you have a 00 - 03 you should replace it. Good luck. Happy Boxstering, Pedro

I have a 99 base. There is an "overfill" discharge hose for where the coolant reservoir/oil filler is located that drains by the right rear wheel. Take off both fill caps and remove the flat plastic horizontal plate under them. You will have to pull off the rubber gasket/ring above it. Almost center in the bottom there is the overflow tube. Pour some water in it to see if it is coming out where your leak is. If so you might just need just need a new coolant cap

Thanks Krieger and Pedro. I'll have a go at what you've recommended this weekend and let you know how I get on.

Thanks for your help guys, I've just pulled the carpet out and no signs of any coolant. Everything's dry and no signs of any previous leaks either. I had a look at the coolant cap and the part number on it is 996.106.447.01 so looks like that needs replacing. I then lifted up the plastic horizontal plate and there was lots of signs of moisture and coolant in the little gaps and corners so definitely looking like it's the cap. Will get a new one ordered asap

Cool! Love the easy fixes.

Came out of KFC a few years ago and saw coolant all around the rear of the car, started it up and it was fine, trying to get it home a very short distance. By the time I got home she was running pretty warm. It was the coolant cap, went to the dealer and like $60 for a coolant cap, but it is what it is. Fixed the problem. Like you I love the easy fix.

Extremely interesting thread. I have smelled coolant in the car for a few months, and in the last week I've been seeing coolant drip from the right rear wheelwell. I figured it was time for a new coolant tank. But I decided to take Krieger's lead and make sure that I don't just have a bad cap. Here is a pic of what I found, dried coolant coming out from under the bleed valve. So what do I do about this? Is there a gasket under the bleed valve that can be replaced?

OK, I answered my own question by searching and I found a thread from 2013...there are two O-rings under there that must have gone bad. I will probably replace the bleed valve for good measure. My cap is an -04, seems fine.