I've got a 95' Si and i've never had any problems with my engine overheating etc., but no matter how much coolant I put into the overflow bottle it's pretty much down to nothing in a matter of weeks. When I open the rad cap, there is enough coolant there, but the overflow bottle never stays full. I've taken the plastic bottle out when i changed my rad and filled it with water, and nothing leaked out.

Any suggestions as to what might be causing this?

thanks

 

I say check your hoses for leaks or anything first. When your coolant gets hot your hoses can expand and leak somewhere.

 

your evaporating water somewhere

 

If you don't find any leaks that way it may be possible that you blew your head gasket and are burning the coolant. You could try taking a look at your spark plugs and see if there is any spots or coolant deposits. You can check your exhaust too...might smell funny or you might catch some fluid coming out. Don't be mistaken for the condensation though. Hopefully you just have a leaky hose.

 

thanks for all the info.

the hoses were actually leaking last year and I replaced both of them, so it must be something else.