Unexplained coolant loss

[Jeff Telford]

I have a 2006 Mercury Mountaineer 4.6L 2wd drive premier, that is losing coolant with no drips or puddles. I have already been down the road with the radiator pattern failure, changed the hoses & thermostat (OE). Recently I had a heater hose that cracked at the Y, and have replaced it coolant level held for about a month with no loss. Now it is back to losing coolant and the sweet smell of coolant is present. Is there another pattern failure I’m missing? Any other ideas of components to check?

Topic

[Kasra]

•Can you smell it from the vents? It could be a leaking heater core or leaking somewhere into the dash.

•Is your motor oil still black/oil colour or is it creamy? Could be leaking into engine.

•How is your transmission fluid level and or color? Could (very unlikely) be leaking into the transmission cooler lines in the radiator.

•Is the coolant still the proper color? Or transmission fluid or motor oil could be leaking into the radiator or visa versa.

•Or it could be leaking onto the exhaust and evaporating (hence the sweet smell) but not visible sighting of the liquid.

•Or it could be a cylinder head gasket leaking into cylinders and combusting.

•As you can tell it could be leaking any where. Either way it is hiding/going some where.

[Jeff Telford]

No internal smells

Motor oil has no evidence of contamination

Trans is a 6R60, bless those engeniers the put a small dip stick about 4inches from the cat. I need to check the level however the trans is not showing indications that the fluid was contaminated (no rough shifting or general Trans issues). A very valid point due to the radiator issues know to this model.

Coolant is green, no indication of contamination.

I preformed a block test for combustion gases results were negitive.

I think we have a winner on the leaking onto the exausat system. Looks like I’ll be pressure testing the syst while everything is cold. That should allow for me to see a drip path or perhaps even get a puddle. The system has never overheated due to this coolant loss, I should have pointed that out in my initial post.

[Jeff Telford]

Pressure test revealed that the engine side of the lower radiator hose had been poorly clamped :whistle: ….. I adjusted the hose and reclamped slightly tighter & now the system is holding pressure and no other leaks have been detected….. The size of the leak was very small and where the coolant was discharging explains why I was never able to locate drips or puddles. Thank you very much for your input, you diagnostic questions got me thinking outside the box. banana:

[Author]

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