Coolant is leaking from the car but no overheating..

If your 2012 BMW 535i is losing all of its water but not overheating, there could be a few possible causes:

1. Leak in the coolant system: The coolant system of your car may have a leak, which is allowing the water to escape. This could be caused by a faulty radiator, a leaking hose or a cracked engine block.
2. Evaporative loss: In some cases, the water may be evaporating due to high temperatures. This is common when driving in hot weather, and it can be caused by a malfunctioning pressure cap or a faulty radiator cap.
3. Leak in the water pump: The water pump may be leaking, causing the water to escape from the coolant system.
4. Leak in the head gasket: A leak in the head gasket can allow coolant to leak into the engine oil, causing the water to disappear.

anon#2
never do that
get the car fixed in a shop or burn up the engine you will.
I answered your first post anon

My only guess is either the temperature pressure switch is malfunctioning, or you have a leaking intake manifold. I would do a coolant pressure test on the radiator, put a/c on full blast while driving, or turn a/c completely off while driving. BUT, drive a good distance, when doing both. Release pressure before driving. As soon as you get back, do another immediate pressure test, then check your heater hoses under dash behind motor for leaks. This will put severe strain on the heating and cooling system as well as the a/c accumulator and condensor lines. Hope this helps

Are you sure that it is coolant. Puddles form under vehicles where the AC drain is under the car. Check that the puddle is actually coolant and not water from the ac evaporator core.

Low coolant

Check it when cold,not just
the overflow tank ,the remove the coolant
cap & check

May want to check the a/c housing drain also

Coolant leaking from a bad head gasket

The coolant has to be escaping from the system some place. Coolant does not just disappear. It could be escaping thru the tail pipe as white smoke while the engine is under a load. Radiator cap could be letting it seep out as steam also, but I would imagine you would see or smell this if it were the case. Front passenger floor I'm assuming is not wet and coolant is leaking from the heater core assembly? Has the system been pressure tested with a coolant pressure tester and watched to see how long the pressure stays up?? (engine cold of course)

depending where the water is leakn from if the water is cold it may be condinsation from air conditioning

When the car is completely cool,check the electric fan(s) for smooth rotation.

Clean/check/change the thermo sensor,contact and wire.

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Excavate air pocket in coolant system / check for head gasket leak

This test will kill two birds with one stone.

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MAKE SURE THE COOLANT SYSTEM and ENGINE IS COLD!

RAN THIS TEST IN A WELL VENTILATED AREA ONLY!

You will spill some coolant during this air pocket purge test.......BE KIND TO THE ENVIRONMENT and ANIMAL please clean up after the test!

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Put the front end on a pair of ramp or park your car on a VERY STEEP HILL (radiator facing top of the hill) .

Top of the coolant reserve tank

Let it ran for 10-15 minutes.

Monitor for air pockets escaping from coolant reserve tank.

Small amount of bubbles is OK at 1-5 minute mark

After the thermostat open up (after 195 F warm up) at
5-12 minute mark or after high idle you should see less bubbles.

If you do not see any in rush of bubbles then your thermostat may be partially stuck or rusted badly inside the thermostat hosing.

Give the thermostat host few gentle taps.

If you see larger bubbles surfacing after 15 minutes then should do a hydrocarbon (HC) dye test to test for potential head gasket leak.

Let engine cold down and top off coolant reserve tank.

Start monitor for coolant lost

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A coolant flush is require every 2 years or 24,000 miles.

I recommend the thermostat that has a relief pop-let to reduce the change of burst radiator and coolant hoses.

Make sure you get a new thermostat gasket,black RTV and fresh coolant for the job.

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most likely when you replaced coolant line and refilled rad the system was not bled properly.
fill the system with 50/50 again and top up the reservoir. run the engine to 2000 rpm and look at temp gauge . it should rise to middle and drop to low this means t stat opend and air is out now let engine idle and top up coolant. good luck