SOO i've got a coolant leak that i cant pin down... I have had the radiator replaced on the car after the old ones stop leak finally gave away (previos owner is responsible for the stop leak) . i had my mechanic replace the radiator and also checked the timing belt that the previous owner had replaced, he found the tensioner on wrong and had to replace the tensioner and re assemble the timing belt assembly. since ive had the car back it has leaked coolant first from the big hose that comes out the bottom of the radiator on the drivers side. i tightened that. but the car is still loosing coolant, ive checked the oil and it free of coolant, and the heater core has been replaced within the last 5,000 miles , the coolant level seems to slowly drop to a bit below the minimum line on the reservoir within about a week of my regular commuting (30 miles some highway) , and then stabilize/ leak much slower. until yesterday when i filled the reservoir from minimum to the max line then drove about 20 miles around town and then home. When i started the car this morning, the low coolant light came on and upon inspection, my coolant had gone from full to just below the minimum line over night. any ideas about where to look for the leak? could it be leaking when i accelerate hard or put pressure on the system?

Barring any external leak, like the upper hose and recheck the bottom hose fitting - too tight and you will breake the plastic fitting, you will have to consider the reservior cap being bad, the connection at the bottom of the reservior being cracked, or any where else - like the heater core.

For engine coolant loss, remove all 5 spark plugs. Then with a small flashlight, shine it into the cylinders. If you see a 'clean' cylinder, that could be from coolant. A compression check will also confirm.

I would first concentrate on externals around the engine bay. Do that when the engine and coolant are hot. Use a clean paper towel, the blue/green will show up much easier. The cabin heater core can be easily seen after removing the kick panel.

Klaus
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There is no present time, just the past and future

thanks again man, it was the plastic elbow on the reservoir, i have the new one , i'm just waiting for it to empty itself.

Thanks Klaus , ill check as soon i find myself with freetime and some sunlight.