I posted last week that I was doing some spirited driving when I experienced a sudden loss of coolant accompanied by a lot of steam. After having lost coolant, I got the low coolant warning on my dash. After a few days or so I got the time to check the coolant levels and it sits at about half full. I unscrew the coolant cap and coolant starts gushing out. After replacing the cap, the coolant stops leaking. I've taken a few photos of where I believe the coolant is leaking from. My guess is that I don't have the issue that require the welding or new adhesive, rather it must be a hose, coolant tank, or water pump? Anyone have this problem before?

 

That's crazy! Sorry to hear about that. I wonder if this is the coolant tank issue that we've been hearing so much about lately...

 

Could also be a bad seal around the coolant cap for the expansion tank. Coolant gushing out when you remove the cap on a hot engine is normal since the system is under pressure.

 

The coolant gushing out isn't when the car is hot though. It's gushing out of the bottom of the engine I'm guessing because the system isn't pressurized anymore?

 

It's not the tank - that would be a very slow leak. I vote for the cap being the problem. Since you lost a lot of coolant already, you probably have air in the system that forces coolant out when you de-pressurize by removing the cap. Get that reservoir topped up and make sure the cap is very tight (or get a new cap). It could be worth doing a pressure test to make sure you don't have a weird hose leak somewhere too. All of this is simple stuff and won't break the bank.

 

Have it looked at. There are several "common" possibilities like; tank, cap, hard lines or even the soft hoses.
Good luck.

 

a pressurized system even after sitting for a few days can be a sign of a bad head gasket as well, which lets combustion gasses get into the cooling system. At least that is a tell-tale system on e36 m3's.

 

Be sure to use the correct coolant as well - I don't think green is the right kind, but could be wrong...

 

Cap usually go away regardless of miles at about 8-10 years. Cheap fix, just a PIA to find right away.