Hi everyone.

I have noticed that sometimes after very hard ride on my AWD R coolant cap starts to leak like so:

https://files.fm/u/e62w455jd

Any idea what that could be?

I have also noticed that the cap sometimes doesn't want to "click" when turning on so that I have to repeat it few times before it "clicks".

During "normal" driving conditions it doesn't happen. Sometimes when I press the car hard everything is fine too. It seem to happen only after really hard ride and relatively high ambient temps.

 

Suggests over-heating is causing the tank to over-pressurize and leak.
I guess it depends on what you mean by "very hard ride".
For example , if you mean driving at 80 mph for an hour, then I do not think this should happen.
OTOH, if you mean driving at 140 mph for an hour (presumably on a track), then it suggests you need a different thermostat and/or cooling system.
If it is really leaking all the time, just replace the cap.

 

I've seen a couple of posts from people that have needed to replace the cap to fix an internittent leak. Not a common issue, but one that crops up occasionally.

 

That trail of coolant (and the 'click' issue) indicates that the cap is bad.

To play it safe: Unscrew the cap (cold) and also check the mating surface on the reservoir for damage/gouges that would prevent proper sealing.

 

Thank you all for the guidelines.
I have ordered new cap, which should arrive within 10 w/days.
Till then I have to play my toy relatively safe.