Losing coolant

DEREK SCARHEAD PARK

MEMBER
2003 FORD MUSTANG
3.8L
6 CYL
RWD
AUTOMATIC
145,000 MILES

So am I am losing coolant, or in the case water, at an alarming rate. I took it to a mechanic and got royally taken advantage of because the issue still exists. He ran every test under the sun, pressure test, tested the radiator, he swears it is not an overheating issue, which I somewhat agree with, however, the coolant being lost is causing it to overheat. He said the head gaskets are good, no cracked block. I do not know what else there is to check here. I even bypassed the heater core, because I was getting a slight drop of fluid inside the car, so I suspected it might be the heater core, that apparently is not it either. Please help! Please let me know what other details you might need to diagnose this issue. The car ran fine and would not overheat as long as I kept fluid in it, as of right now, the temperature gauge is starting to drift towards hot after a short drive and the reservoir tank is full like it has not lost a drop. I am baffled!

2 Replies

HARRY P

MECHANIC
2,291 POSTS

Personally, I would redo the pressure test myself, because I do not trust a mechanic who cannot find a coolant leak. That is something you learn in Auto mechanic 101. So go get your own pressure tester. They can be bought online on Amazon for like $50.00, or borrow one from the local parts store with a loan-a-tool program (They require a deposit, but it is refunded when you return it). Fill the radiator. Then, with the cap still off, start the car, turn the heat on, and let it idle and warm up some and keep topping off the coolant until it seems like all of the air bubbles are out. Then shut the engine off and simply hook up the tester where the radiator cap goes and pump up the pressure to whatever your radiator cap specifies (probably about 15 psi). Then start looking for a leak.

Here is a guide: https://www.2carpros.com/articles/radiator-pressure-test

Start here and let us know. If you do not find a leak at first, try again. If there is a leak, you will find it. You may not see it, but you will hear it hissing if nothing else.