I've been having this problem with my 97max for a while and I can't seem to figure out what it could be. When I drive my car it runs fine but when I park and get off..there is extreme amounts of bubbling coming from the radiator reservoir tank and I lose all (or most) of the fluid through the breather hole. I cleaned out the reservoir tank and have added a system flush to my radiator thinking it could be dirty but it still does the same thing. Any suggestions on what it could be? Thanks in advance.

 

Repalce your radiator cap.

 

already did..got a new one and it still does it.

 

prob have a clog in the raidiator flush the system w/those prestone kits

 

A radiator flush is not going to help a clogged radiator. Also check your thermostat it may be stuck closed, also your water pump might be shot. A radiator shop usually opens up the radiator to clean it. Not sure if that can be done to ours since the top and bottom of our radiators are made of plastic. Anyone here have there radiators cleaned?

 

I would also say check your thermostat. I bet you its stuck closed and its a easy fix

 

Drain your system. Remove both radiator hoses and flush with a garden hose BOTH directions. Do the same with the engine and heater core.
!!CAUTION FLUSHING A QUESTIONABLE HEATER CORE AND/OR RADIATOR MAY RESULT IN LEAKING!!
Reconnect hoses and fill with 50/50 antifreeze/DISTILLED water. Tap water and filtered drinking water contains minerals that are detrimental to engines and their cooling systems.
Your symptoms are also indicative of a blown head gasket. A shop can perform a block test (test the gasses in your radiator for exhaust fumes). That will tell you beyond the shadow of a doubt whether its a HG leak.

 

Flush additives are meant to be added BEFORE doing a proper flush. Flushing as explained above WILL fix a clogged radiator. Whether yours is clogged or not is another matter.
Replace your T-stat after flushing, and after filling, run the engine cold with the radiator cap off. As the T stat opens you should see the coolant flowing in the top radiator tank. If not its likely a pump problem.
Before wasting time and money though, Check for blown HG. You can do that as simply as removing the radiator cap and smelling the coolant, and looking for black junk floating in it, although having it tested would be the best bet. Don't spend money on a leakdown test, as that takes longer and will cost more, many shops will do a block test (explained in above post) for free in hopes that they'll do the repairs. If they charge it'll be minimal.

 

Are you sure that you are losing coolant from the reservoir breather hole, not blown HG? I would test for blown HG first...

 

Blown HG CAN push coolant out through reservoir. The only question is, Is it just getting hot and boiling out, or are compression gasses PUSHING coolant out?