Trying to Find a Coolant Leak
 

So i am going through a lot of coolant each month in my 03 disco. I don't see any leaking when I am parked and my oil is fine. When i turn I can hear a sloshing sound and smell it when the heat is on so I figured it's the heater core. After reading some posts i tried to see if it might be the o ring so i took apart the floor vent on the passenger side and took a picture of what I think is the connection to the heater core. I am not very mechanically inclined, so I want to get some direction before I tear things apart. I don't see any crud around the connection and my carpets are dry, so where does this leave me and my leak? Any ideas etc would be greatly appreciated.

Would wait on the the heater core dismantle.

1. Your coolant leak could be small, and in the engine bay, and the smell could be sucked in through the fresh air vent for the heater/AC. Do you smell that sweet coolant smell at the exhaust? Is there white smoke from exhaust after engine has warmed up? Burning coolant inside engine is usually head gaskets or valley pan gasket.

2. The heater core in a D2 and late model year D1s has coolant running in it all the time the engine is running. No valve turns off the hot water. So any bubbles in the cooling system can make their way through there, making the sloshy sound.

3. If you are going through coolant, and no wet spot on carpet, may not the be heater core.

4. Common leak places under the hood are any and all hose connections, the small heater plate under the throttle valve (it keeps it from icing up and sticking wide open), valley pan gasket, water pump seal, and of course head gaskets. Page attached of coolant flow.

5. You can borrow a coolant pressure tester from an auto parts store, and run PSI in coolant up to 20 PSI, and wait 30 minutes to see if leaks appear or pressure drops. There is a UV dye that can be added and searched for with a black light, but you have no visible leak, might not be the approach.

6. The auto parts stores sell a chemical test for combustion gas in coolant, about $50, will do over a dozen tests. This would confirm you have leaking head gasket.

7. Please note that coolant loss can increase quickly, good idea to check level daily while you sort this out so increased loss does not leave you overheated. You did not mention miles on truck. If you see temp gauge above 9:00 you are starting to overheat, watch it carefully.