as the title says my buddy has a 2002 forester has the 2.5 in it he has a radiator leak for most of the summer but says he never let it overheat and was adding coolant all summer recently i replaced the radiator and stopped the coolant leak. now hes been telling me that he has still had to add coolant every other day its dissapearing and not leaking. i checked the car yesterday and the coolant was full but he told me that he added some that morning. i couldn't see any leaks and the car is not overheating. where is the coolant going? the oils normal its not puffing out white clouds. is this the start of head gasket failure?

 

Recheck the hose clamps.

If you're losing that much coolant, and you're not experience any drivability issues.

There's an external leak somewhere.

 

Just gotta find it.

Run it to operating temp and check the overflow bottle for bubbles and/or coolant pushing out of the bottle.

If he's losing enough that he had to add every few days and there's no evidence of coolant on the outside of the engine or on the ground, that's usually a pretty severe head gasket leak. Externally the head gaskets often leak on the lower rear corners of the block/head mating surface which is usually the hardest to spot. Have to be under the car and look up with a bright flashlight. It can often just look like a greasy blob mess on the bottom of the block, but if there's any yellow or greenish blobs mixed in that's the sign of coolant.

 

These rarely mix coolant and oil, and almost never smoke even when coolant is being burned in the combustion process. Also pointless to try any of the chemical test kits, they are never conclusive on these cars. Leak down test will confirm a head gasket leak of coolant into the combustion chamber.

look at the seams between the head and block.

 

specifically the rearward edge on the drivers side, and the frontward edge of the passenger side.  Basically the lower righthand corner of each head.....that's where the leak externally.

Verify no external leaks that have been missed.

 

Sounds like headgaskets, they've probably been replaced before or were overheated this summer during all that playing around adding fluid, etc. I guess someone could be very diligent but it's hard to hit it perfect every day. In any event previously replaced gaskets or overheating can cause non typical symptoms and failures like you're describing.