loosing antifreeze but no leaks, no heat. cold in Ohio
can not find any leaks anywhere
no wet spots after running car
put antifreeze in jug and run car check next day and its empty
have little heat when car is ideling soon as i drive it gets cold
oil looks normal on dipstick dont think its head gasket
Is the passenger side front carpet wet? You may want to go and get it pressure checked to find the leak.
May be the heater core.
Is there white smoke coming from your exhaust pipe? Does your engine oil look all milky?
Heater core is unlikely. If you're loosing the quantity you say you are your interior would be flooded by now. If its not showing up on the ground or in the oil it pretty much has to be going out the exhaust which most likely means a failed gasket. The best fix is to pressure test the cooling system and also do a compression test on the engine to pinpoint the problem and then fix it. A band aide fix that might work would be a couple of applications of Bars Leak. If the leak isn't too huge that might fix it or at least slow it down at least temporarily.
Looking for a Used Grand Prix in your area?
CarGurus has 3,715 nationwide Grand Prix listings starting at $879.
Search Pontiac Grand Prix Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Pontiac Grand Prix Experts